Life-cycle assessment of construction product data Environmental impact … assessment... ·...

Life-cycle assessment of construction product data

Environmental impact of higher recycled content in construction projects

Date: July 2007

Environmental impact of higher recycled content in construction projects 2

Contents

Executive Summary 3

Glossary of Acronyms 10

1 Introduction 11

2 Recycled content Quick Win categories 21

2.1 Unbound aggregates 22

2.2 Asphalt paving (ex-situ) 33

2.3 Ready-mix concrete (RMC) 37

2.4 Precast concrete paving 42

2.5 Dense blocks 49

2.6 Lightweight blocks 53

2.7 Roof tiles 56

2.8 Clay facing bricks 62

2.9 Plasterboard 66

2.10 Chipboard 70

2.11 Thermal insulation 73

2.12 Ceiling tiles 78

2.13 Floor coverings 83

2.14 Drainage pipes 86

3 Case studies 90

4 Data gaps 115

5 Conclusion 117

Disclaimer: This analysis was prepared by the Building Research Establishment (BRE) and has been published in good faith by WRAP, and neither WRAP nor BRE shall incur any liability for any action or omission arising out of any reliance being placed on the report by any organisation or other person. While steps have been taken to ensure its accuracy, WRAP cannot accept responsibility or be held liable to any person for any loss or damage arising out of or in connection with the information in this report being inaccurate, incomplete or misleading. The listing or featuring of a particular product or organisation does not constitute an endorsement by WRAP and WRAP cannot guarantee the performance of individual products or materials. For more detail, please refer to our Terms & Conditions on our website www.wrap.org.uk. Published by: Waste & Resources The Old Academy Tel: 01295 819 900 Helpline freephone Action Programme 21 Horse Fair Fax: 01295 819 911 0808 100 2040 Banbury, Oxon E-mail: [email protected] OX16 0AH


Executive summary

Construction clients, policy bodies and planning authorities are increasingly setting requirements for projects to measure and increase reused and recycled content. They are asking project teams to adopt the most significant opportunities for cost-neutral good practice within the chosen design, by identifying the top 5-10 substitutions specific to the project where one product can be replaced by an equivalent with higher recycled content. Alongside waste reduction and recycling, this reuse of recovered material is one contribution to the efficient use of materials – driven by objectives such as cost-saving, diversion from landfill, carbon saving and corporate social responsibility. Who is setting requirements?

The Scottish Executive has asked all public bodies in Scotland to set 10% recycled content as a minimum standard in major public sector projects in Scotland. Councils including Aberdeen, Glasgow, Midlothian, South Ayrshire and the Shetland Islands have already taken action, as has Scottish Water.

The Central Procurement Directorate in Northern Ireland issued such guidance in February 2006. The Welsh Assembly Government has set the same standard in major regeneration projects and

health sector procurement. The Olympic Delivery Authority has adopted minimum standards for recovery of demolition

materials and recycled content for London 2012. In England, the Building Schools for the Future programme, Defence Estates, the National

Offender Management Service and hospital PFI projects have all adopted KPIs and benchmarks for recycled content.

Property developers and retailers including British Land, Hammerson, John Lewis Partnership, Marks and Spencer and Stanhope have done likewise.

Potentially there are significant environmental benefits from reusing waste materials and incorporating them in manufactured construction products. However, to date there have been relatively few studies that have looked at these impacts in a robust and scientifically rigorous way, and none that have tried to tackle a broad grouping of material types at the same time. This report assesses the difference in environmental performance that results from using greater levels of recycled material at no extra cost in construction projects. Many gaps and weaknesses in data have been found, and therefore the findings should be regarded as indicative and not absolute. General trends of environmental performance have been analysed for fourteen product categories that commonly offer the most viable and cost neutral options for increasing recycled content (termed ‘Quick Win’ categories). Twelve environmental performance indicators, including diversion from landfill, have been evaluated where possible for each of the fourteen product categories using life-cycle assessment. The results have been presented for carbon emissions (kg CO2 eq. (100 years)); and for all twelve environmental performance indicators combined, in the form of the Building Research Establishment’s (BRE’s) overall “Ecopoint” score. (100 Ecopoints is equivalent to the environmental impact of the average UK citizen over one year.)


For those product categories where sufficient data exist for conclusions to be drawn:

on average, adopting higher recycled content reduces overall environmental impact in each product category; and

higher recycled content may or may not reduce carbon impacts – in the case of aggregates the key factor being to ensure that recycled aggregates are sourced more locally than the quarried aggregates they replace, or are processed using energy-efficient equipment.

In addition, using recycled material reduces landfill by productively taking material out of the waste stream, as well as helping to reduce the extraction of primary resources and production of quarry overburden/waste. Reduction in minerals extraction is typically a major reason for Ecopoint scores improving more sharply than carbon performance. However, it is also true that higher recycled content does not automatically yield environmental benefits in every situation. In particular, the substantial variation in environmental impact between competing products at the same level of recycled content means that the trend is not a universal rule – some individual products may “buck the trend”. This is often symptomatic of different manufacturing sites being of different size, age and efficiency, and having different product portfolios or handling their waste emissions in different ways. As a result, it is often not possible to attribute a change in environmental performance simply to whether a manufacturing site uses higher recycled content. Although higher recycled content invariably correlates with lower overall environmental impact, certain specific environmental impacts can increase, e.g. depending on the brand. In particular, there are cases where a manufacturer may use more energy to transform waste material into a useable product – for example, if a manufacturer uses more cement to incorporate recycled aggregate into a product, or if a manufacturer or construction site sources recycled aggregates from a greater distance (although transport costs would act against such practice). The current report has called upon extensive data from BRE’s work on Environmental Profiles and the Green Guide to Specification. Priorities for further data collection have been identified, some of which are being addressed through the current revision of the Green Guide. The summary table below quantifies the trends in environmental impact with recycled content, estimated as the best fit through data points for individual products and their manufacturing processes. The data cover the manufacturing life-cycle through to the product leaving the reprocessing plant – hence excluding the transport to the construction site. Without exception, for those product categories with adequate data, higher recycled content corresponds to an environmentally positive reduction in Ecopoints. The average carbon performance in some product categories improves with higher recycled content, whereas in others it worsens (associated mainly with poorer energy performance measured on some aggregate recycling plants compared to quarry processing plant). Headline findings for each product category are as follows: Unbound aggregates

Crushed rock (or gravel in the case of pipe bedding) is compared with aggregate from construction and demolition waste (CDW, from off-site reprocessing).

There is a large range in environmental impact from different plants processing the same type of aggregate – 100% or more.

As an average across the plants for which data are available, reprocessing plant for recycled aggregate has ~50% higher carbon impact than primary aggregate processing – although the


best performing recycled aggregate for granular fill is roughly equal to the best performing primary aggregate in carbon terms. This excludes the carbon impact of transporting the aggregate to the construction site. (Note that existing life-cycle assessment data are limited on some stages of aggregate production, especially for recycled aggregates, and work is underway to produce more complete data.)

On an Ecopoints basis, the recycled aggregates all perform significantly better than all the primary aggregates at the ‘factory gate’.

If transport to site is factored into the analysis, recycled aggregate has a lower carbon impact than primary aggregate provided it is sourced at least 10km by road closer to the construction site than the primary aggregate (or less if the primary aggregate is additionally part-transported by rail or ship). Conversely, primary aggregate would have to be sourced at least 220km by road closer to site to achieve an Ecopoints advantage over recycled aggregate.

If recycled aggregate is processed in-situ on the site where the CDW arises, then using that aggregate on the same site is estimated to be better in terms of both carbon and Ecopoints compared to importing primary aggregate. The recycled aggregate also has a small carbon/transport advantage over primary aggregate when supplied to another construction site.

Currently local use of recycled aggregate is common for economic reasons, but the carbon benefit adds a further reason for encouraging the use of recycled aggregate as locally as possible.

Asphalt paving (ex-situ recycling)

Data are available only for hot reprocessing of asphalt planings ex-situ. Warm and cold processing and in-situ processing could not be evaluated (but might be expected to have a lower carbon impact, as illustrated by contractor data from individual case studies).

The use of 14% planings in an asphalt mix is estimated to reduce both the carbon impact and Ecopoints burden (per tonne of mix leaving the asphalt plant). It is assumed that primary and recycled asphalt can be supplied to the construction site from equal distances (since the ex-situ asphalt plants studied are able to supply both types).

Ready-mix concrete

Moving from standard practice to good practice in all ready-mix concretes (RMC) has both carbon and Ecopoints benefits. This is not due to the use of recycled aggregate, but a consequence of reducing the cement content by using ground granulated blast furnace slag (GGBS) or pulverised fuel ash (PFA) as a cement replacement.

Transport is not a major factor relative to the environmental impacts associated with cement production, and transport costs will limit the distances travelled from the RMC plant, avoiding any significant differences in transport-related carbon.

Precast concrete paving

Good practice recycled content gives an Ecopoints benefit for all the products considered – paving blocks, paving slabs and reconstituted stone paving blocks. For paving slabs, a reduction in cement content (as a result of replacement with PFA) can also reduce the carbon impact. However, for reconstituted stone paving blocks, a marginally higher carbon impact is calculated as a result of the carbon penalty attributed to the average recycled aggregate processing plant (described above).

For this and the other product categories summarised below, the environmental impacts associated with typical transport of the manufactured product were found to be insignificant compared to the overall environmental impacts of production.


Dense blocks In dense blocks, there is a general trend for increased recycled content to increase carbon

emissions (as a result of the carbon penalty attributed to the average recycled aggregate processing plant, and some tendency for manufacturers to increase the cement content). However, the Ecopoints score improves.

There is significant variance between brands – for example, depending on which brands are compared, blocks at good practice may have lower or higher carbon/environmental impact than blocks at standard practice..

Lightweight blocks

For lightweight blocks, adopting good practice recycled content has no significant impact on carbon emissions, but improves the Ecopoints score (on average).

There is significant variance between brands – for example, the best performing lightweight block at standard practice has lesser environmental impact than the worst performing lightweight block at good practice recycled content.

Roof tiles

Improved environmental performance with higher recycled content constitutes the average trend for concrete and fibre cement roof tiles, but the performance of individual brands varies significantly between different plants and manufacturers.

Clay facing bricks

No conclusion – bricks vary significantly in their use of recycled content, but no quantitative trends on environmental performance can be determined from the data currently available.

A key issue for manufacturers is whether recycled content will improve their energy use, as this has a major bearing on manufacturing costs and environmental impacts. Trials funded by WRAP (Waste & Resources Action Programme) have illustrated the potential to reduce firing times and temperatures by adding ground glass to bricks, but the results are not necessarily applicable across the range of brick manufacturing processes and products.

Plasterboard

No conclusion – more detailed life cycle assessment data are needed to characterise the possible effects of using recycled or synthetic gypsum within plasterboard.

Chipboard

No conclusion – more detailed data are needed on the collection and reprocessing of waste wood in order to identify any significant change in environmental impact with higher recycled content.

Thermal insulation

No conclusion for glass wool, cellulose fibre and mineral wool on the variation in environmental performance with recycled content within each product category – owing to limited availability of data on individual brands.

For expanded polystyrene, moving to higher recycled content improves both carbon and Ecopoints results – although the best performing brand at 0-5% recycled content performs nearly as well as insulations with 35% recycled content.

Comparing across the four types of insulation, carbon and Ecopoint performances are comparable. (Cellulose insulation is attributed negative carbon impact at the factory gate due to


its sequestration of carbon in the trees used for newspaper production, but this benefit is cancelled on final disposal of the insulation, unless the insulation itself is recycled.)

Ceiling tiles

No robust conclusion for gypsum or mineral ceiling tiles – due to data limitations. Floor coverings

For floor tiles, the general trend is for environmental performance (carbon and Ecopoints) to improve with recycled content above 0%. However, comparing individual brands, tiles with moderate levels of recycled content (10-30%) can perform equally well if not better than tiles with even higher recycled content (50%+).

Drainage pipes

No conclusion – due to lack of data on specific drainage products.


Table of life-cycle assessment (LCA) results:

Standard practice recycled content (%)

Good practice recycled content (%) Data Quality

Average % change in carbon emissions

Average % change in overall environmental impact (Ecopoints)

Aggregates (unbound) Granular fill 0 100 50% -79%Pipe bedding 0 100 49% -80%Sub-base 0 100 50% -79%

Asphalt (ex-situ) - 0 14

5 LCA industry data sets

-4% -9%

Ready mix concrete (RMC) RMC up to strength C25 0 24 -16% -26%

RMC above strength C25 0 7 -42% -27%

Precast concrete paving Concrete paving blocks (CBP) 5 50

No significant discernible difference

-21%

Concrete reconstituted paving blocks 5 40 2% -6%

Concrete paving slabs (flags) 3 20 -4% -11%

Dense concrete blocks - 5 50


4% -16%

Lightweight concrete blocks - 50 80



-15%

Concrete roof tiles Concrete tiles 0 10



-7%

Fibre cement tiles 0 5


-7% -9%

Reconstituted resin bonded slates 43 80Polymer-modified cement tiles

Clay facing bricks - 0 10Plasterboard - 0 47Chipboard - 65 70Thermal insulation Glass wool 30 50

Cellulose fibre 80 85

Expanded polystyrene (EPS) 0 25


-27% -29%Mineral wool 50 50

Ceiling tiles Mineral ceiling tiles >10 <50Gypsum ceiling tiles 36 84

Floor coverings Generic carpet tiles 0 50


-16% -20%

Drainage products PP 0 75HDPE 20 45PVC 0 10

More research and data collection required


Constructed from LCA data sets from similar industrial processes

30



Change from standard to good practice recycled content

Sub typeQuick Win Category




Green cells indicate a general trend of benefit with increased recycled content Orange cells indicate a general trend of disbenefit with increased recycled content


Case studies Fourteen case studies were analysed to estimate the overall impact of moving from standard to good practice recycled content across the “Quick Win” product categories for each project (e.g. in response to a client requirement). For all but one of the case studies, against the criteria of kg CO2 eq. (100 years), Ecopoints and landfill/overburden, there was a significant benefit – for example, landfill diversion ranged from 11 tonnes for a house to 5,000 tonnes for a large commercial building. The one exception was the widening of the M25, where the use of recycled materials was modelled as reducing the Ecopoint score but increasing the associated carbon emissions. However, this carbon result is based on average plant data and generic assumptions about the delivery distances of recycled and primary aggregate to the construction site – whereas in practice it is likely that there would have been a carbon benefit, for the following reasons:

The M25 widening used recycled aggregate for around 90% of the unbound aggregate requirement, over 800,000 tonnes in total. Reuse of materials arising on site accounted for 35% of the total tonnage; the other 65% was sourced from the local London area, and had a £4/tonne cost advantage over comparable free-draining primary aggregates which would have had to be imported some distance from the Mendips or Leicestershire.

As noted above, reuse on site has a carbon advantage over primary aggregate, and sourcing recycled aggregate by road at least 10km closer to the site than virgin crushed rock would cancel out the carbon disadvantage of the average aggregate recycling plant. Therefore, in practice, the use of recycled aggregate on this project would have had a carbon benefit.

This report also demonstrates how to evaluate environmental consequences at the national level if construction projects in general are encouraged to move from standard to good practice levels of recycled content in their top ten product categories. The results are subject to large uncertainties as a result of data limitations, but illustrate the scale of what might be achieved:

Scaling up has been evaluated for one segment of the housing market – timber frame semi-detached new build – based on a specific case study.

By adopting good practice recycled content in 90% of timber frame semi-detached home starts over 1 year in the UK (i.e. in 3,400 units), 8–21 ktonnes of CO2 eq.(100 years) emissions could be saved, as well as approximately 45 ktonnes of landfill or overburden material.

This would equate to cancelling out the carbon impact of between 650 and 1,700 average UK citizens, or the municipal landfill volume of approximately 150,000 average UK citizens.

Timber-frame semi-detached housing accounted for 2.2% of the new housing starts in 2005, and new housing accounted for roughly 30% of all new build and major refurbishment projects. So, if construction clients, policy bodies, planning authorities and development agencies were to ask for good practice on all such projects (i.e. excluding smaller repair and maintenance projects), and if this case study indicated the typical improvement available, the national impact would be more than two orders of magnitude (X100) greater. However, since the 14 case studies show Ecopoint savings ranging from 0.01 to 3.5 Ecopoints per m2 (with timber-frame housing at 0.2 Ecopoints per m2), an accurate assessment of the national impact would require further analysis.


Glossary of acronyms

BFS – Blast Furnace Slag BOS – Blastfurnace Oxidised Slag BRE – Building Research Establishment CBP – Concrete block paving CDW – Construction and Demolition Waste

FBA – Furnace Bottom Ash GGBS – Ground Granulated Blastfurnace Slag NHBC – National House-Building Council PFA – Pulverised Fuel Ash QPA – Quarry Products Association RA – Recycled Aggregate RAP – Recycled Asphalt Planings RCA – Recycled Concrete Aggregate WRAP – Waste & Resources Action Programme


1 Introduction

Aims and objectives of the report The principal objective of this report is to consider the environmental implications of a construction client setting a requirement for recycled content in a project, thereby encouraging contractors to substitute building materials and products with cost-competitive alternatives offering higher levels of recycled content. Data In order to achieve this objective, the Building Research Establishment (BRE) has used available literature, industry feedback and Life Cycle Assessment (LCA) of current inventory data on materials and products from sectors within the construction supply industry. The sectors in question have been identified as commonly offering the greatest opportunity for increasing the overall value of recycled content in construction projects without increasing the cost of materials. This is the first report of its type to consider a wide range of commonly used building materials and products, the potential for increasing their recycled content and the resultant environmental impacts. As a consequence, the report has found that data availability differs significantly across material and product sectors. In the light of this finding, BRE consider that this area of research will evolve, post the submission of this report, in line with an increasing desire to use recycled materials as a matter of economic resource efficiency and for the good of the environment. Background The construction sector is the largest consumer of material resources in the UK and the largest source of waste. Landfill space is restricted, and costs of disposal are increasing. Escalating Landfill Tax and the Aggregates Levy provide direct financial incentives to recover more materials. Reuse and recycling are also recognised as a way of reducing our dependency on finite material and energy resources. Policy and business drivers are therefore pushing for more efficient use of materials – through waste minimisation, recycling and reuse of recovered materials. As one contribution, policy-makers, planning authorities and construction clients are increasingly setting requirements for higher recycled content in construction projects1. WRAP (Waste & Resources Action Programme) is facilitating this trend.

1 For example, the Scottish Executive has asked all public bodies in Scotland to set 10% recycled

content as a minimum standard in all major public sector projects in Scotland, and the Central Procurement Directorate in Northern Ireland issued such guidance in February 2006. The Welsh Assembly Government has set the same standard in major regeneration projects and health sector procurement. The Olympic Delivery Authority has adopted minimum standards for recovery of demolition materials and recycled content for London 2012. In England, the Building Schools for the Future programme, Defence Estates and the National Offender Management Service have all adopted KPIs and benchmarks for recycled content.


Clients and policy-makers typically look for reassurance that higher recycled content, across a project as a whole, will be cost-competitive, practical (i.e. readily available to industry standards with no loss in quality or performance) and environmentally neutral or beneficial. Therefore, to inform clients and policy-makers, WRAP commissioned BRE to compile evidence of the relative environmental impact of zero or lower levels of recycled content versus higher levels of recycled content in common construction products – to see whether those products with cost-competitive “good practice” levels of recycled content offer environmental advantage or detriment relative to “standard practice” levels of recycled content. As such, the report seeks to demonstrate the relative environmental impacts of using more recycled material. The findings are unique to each building product and material, and even within a specific product or material one “recycled” approach may have very different consequences to another “recycled” approach. Therefore, although there is a desire to develop broad conclusions and recommendations, WRAP and BRE recognise that these must be fairly informed by a thorough scientific approach and that the findings may not be clear-cut. This uncertainty is exacerbated by current weaknesses in availability of data on various types of product.

The adoption of a requirement for recycled content A typical requirement might be formulated as follows: ‘….at least 10% of the total value of materials used should derive from recycled and reused content in the products and materials selected. In addition, show that the most significant opportunities to increase the value of materials derived from recycled and reused content have been considered, such as the top ten Quick Wins or equivalent, and implement good practice where technically and commercially viable.’ This form of requirement has two key implications:

it sets a modest threshold – case studies have indicated that most construction projects exceed 10% recycled content even at standard practice (i.e. when no steps are taken to select options with higher recycled content); and

it asks the project team to adopt some of the most viable options for cost-neutral product

substitution with brands/materials that have recycled content higher than standard practice (termed ‘Quick Wins’).

The project team would generally respond to such a requirement using either or both of the following options:

using a higher proportion of recovered materials such as recycled or secondary aggregate, sourced in the local area or recovered on site; and/or

substituting certain manufactured building products with alternative brands offering higher

recycled content. The project team would first determine their design specification against normal performance criteria (cost, strength, durability etc, including a preference for A-rated specifications from BRE’s Green Guide to Specification), and subsequently identify product substitutions within individual elemental specifications (such as blocks with higher recycled content for use in a brick and block wall).


The requirement should be subject to the criterion that the selected Quick Wins are cost-neutral and readily available. The cost evaluation would include transport cost to the site. However, of equal importance is that setting such a requirement will not lead to a significant detriment to other environmental impacts, at the same time as beneficially reducing the demand for finite natural resources and landfill. In addition, policy-makers and construction clients are keen to quantify the positive benefits that can be attributed to the use of recycled materials.

Definition of recycled content A clear definition for “recycled content” is essential to ensure that the conclusions and recommendations offered by this report are robust and consistent with existing terminology. Therefore, this report has adopted the definition cited in the ISO standard on Environmental Labels and Declarations ISO 14021i :

7.8 Recycled content 7.8.1. Usage of terms 7.8.1.1 Recycled content and its associated terms shall be interpreted as follows: 1. Recycled content

Proportion, by mass, of recycled material in a product or packaging. Only pre-consumer and post-consumer materials shall be considered as recycled content, consistent with the following usage of the terms.

2. Pre-consumer material

Material diverted from the waste stream during a manufacturing process. Excluded is reutilization of materials such as rework, regrind or scrap generated in a process and capable of being reclaimed within the same process that generated it.

3. Post-consumer material

Material generated by households or by commercial, industrial and institutional facilities in their role as end users of the product which can no longer be used for its intended purpose. This includes returns of material from the distribution chain.

Note: The definition of recycled content for the target strategy is inclusive of both pre-consumer and post-consumer materials but exclusive of process waste streams when they are reclaimed within the same process that generated them (Section 2.2).


Quick Win categories The concept of a Quick Win category is used by WRAP to identify a construction specification, product or material that offers the opportunity to increase recycled content beyond current standard practice and which at the same time, is cost-competitive to procure and install within a construction scheme. In addition, it should satisfy the conditions of being technically acceptable, meeting the required level of performance, and having reliable supply and availability. Ideally, it should also demonstrate strong environmental credentials – or at least, not introduce significant environmental penalties relative to conventional alternatives. Extensive case studies have shown that, typically on a construction project, the top ten Quick Wins deliver most of the potential to improve recycled content. Although the selection of Quick Wins and their relative importance will vary by project (e.g. new build versus refurbishment), they commonly come from a set of 14 product categories (identified in Section 2). This report considers these Quick Win categories and seeks to provide grounded and robust opinion on the actual benefits and detriments that using higher levels of recycled content in construction can engender. The report content demonstrates that many existing products and specifications do incorporate recycled content and represent practical and viable construction alternatives. Indeed, many leading brands incorporate some level of recycled content – and leading brands may have above-average recycled content. The report is to be used by both policy-makers and the construction sector and has been designed to:

inform clients and their professional advisers on the environmental consequences of procurement requirements – specifically on a kg CO2 eq. (100 years) basis, recognising the significance of climate change, but also on the basis of BRE’s unit of overall environmental performance, the Ecopoint (the greater the Ecopoint the higher environmental impact). The Ecopoint is derived from a holistic life-cycle assessment and combines 12 different environmental impacts.

support Government policy-makers by describing how and why increased levels of recycled

material can be successfully incorporated into construction activity.


Standard and good levels of recycled content Due to the considerable range in the recycled content of construction products, a strategy to distinguish levels of recycled content was established by previous work done by BRE on behalf of WRAP.ii Categorisation of recycled levels under the headings of Standard, Good and Best practice was established under the following definitions:

Of the three categories, good practice was the most difficult to determine. It has been commonly based on qualitative judgement which has taken account of cost, supply and availability, product service performance requirements and technical feasibility. This process was completed by BRE experts with considerable input from material sector manufacturers and trade associations. In this way the values of good practice performance were based on input from a range of industry experts. WRAP has periodically reviewed and updated these benchmarks for recycled content over the last two years. Due to changes in industry practice and additional market evidence, there are a few instances where the previously presented standard and good practice levels may now be out of date. Where this is the case, a possible revised figure is presented in the table of percentages at the start of each product section in the report. For the purposes of this report, a comparative assessment between standard and good levels is used. Best practice may be alluded to at moments where it is informative to the debate but has not been regarded as a requisite within the scope of the report. In general, a client requirement for higher recycled content would encourage contractors to look at the potential to move from standard practice towards good practice – to maintain cost neutrality. Best practice may be more expensive or difficult to procure (e.g. due to a limited choice of brands), and therefore would not be required. Environmental impacts The environmental impacts of extraction of raw materials and water, the processing and production of the construction materials and the waste production of these two aforementioned areas are measured. This is often referred to as a “cradle to gate” approach (the gate being the factory exit gate). In the primary analysis of the different environmental performances of standard and good practice, the transport beyond the factory gate is not considered in order to give an accurate appraisal of processing and extraction impacts before the products are distributed into the open market. However, transport scenarios are considered in a separate analysis for each product category in those cases when the transport from “gate” to construction site can have a significant bearing on the final environmental result. Kg CO2 equivalent (100 years) Kg CO2 eq.(100 years) is a recognised and increasingly used unit of measurement of climate change potential. Other similar metrics such as “carbon emissions” and “carbon footprint” have the same

Standard the recycled content level of specifications, materials and products that are most frequently and commonly purchased in the UK.

Good defined as a cost-competitive level of recycled content which is better than standard but is not necessarily as high as technology/market forces currently allow.

Best the highest recycled content product known to be available on the UK market.


objective of quantifying the climate change potential of a chosen object or operation under study. Although climate change is not the only environmental impact associated with human activity, it is recognised as being the most significant environmental issue facing us today. For this reason, it is used as one of the two principal environmental units of measurement in this report. Complementary to this measure, “Ecopoint” results (explained below), landfill burden and transport are also considered. It should be highlighted that climate change impacts are measured as part of the Ecopoint calculation process. Recognising the significance of climate change, the category carries a weighting of 38% within this calculation process. Therefore Ecopoints provide a balanced approach to environmental impact assessment and take account of the environmental importance of the different impacts facing society today. It is the second principal environmental unit of measurement in this report. Life Cycle Assessment (LCA) and the Ecopoint In the late 1990s BRE devised a method for ranking and scoring different environmental impacts. Known as the Environmental Profiles Methodology, the method combines different environmental impacts into a single score known as the Ecopoint. Using Ecopoints allows decision makers to consider environmental impact criteria alongside other issues in the product and design selection processes. Ecopoints are based on:

Comparison with an average UK citizen’s share of the total UK impact of 12 environmental issues. 100 Ecopoints is equivalent to the environmental impact of the average UK citizen over one year. This is also the same as extracting 138 tonnes of minerals, landfilling 130 tonnes of waste, or manufacturing 75 tonnes (25 000) of bricks. BRE Digest 446[6] provides more detailed information on how the Ecopoints method was developed.

A weighting approach, which involved consultation with representatives of the construction

industry (including government, lobbyists and policy makers), was used to rank and combine the different issues. A repeat of the weightings process has been completed for the update of BRE’s Green Guide to Specifications and the adjusted weightings will be published in 2007. However, the delivery of these weightings has not coincided with the production of this report and therefore the more recent weightings have not been applied. The weightings are updated on a three yearly basis; the 2007 weightings will see a relative reduction in he weighting of climate change, although this remains the leading issue by a substantial margin.

The weightings derived for each impact category that were used in this report are:

Climate change (100 years) 38% Fossil fuel depletion 12% Ozone depletion 8.2% Human toxicity to air 7% Solid waste disposal 6.1% Water extraction 5.4% Acidification 5.1% Eutrophication 4.3% Ecotoxicity 4.3% Summer smog 3.0% Minerals extraction 3.5% Human toxicity to water 2.6%


Allocation of environmental impacts By-products and materials and recycled wastes, which may or may not find application in further processes, have environmental impacts. An allocation rule is needed to assign these burdens appropriately between the co-products and reusable or recyclable wastes. ISO 14040iii recommends a series of priorities for allocation as follows:

avoid, by division of a single process into sub-processes; by system expansion to avoid allocation; by physical property (e.g. mass or calorific value); and by product value.

BRE has used the following, in order of preference:

avoid, by division of a single process into sub-processes; by physical property; and by product value.

BRE recognises the desirability of avoiding allocation and therefore separates processes into sub-processes to avoid allocation wherever possible. To achieve the goal of the BRE study, it is necessary to have a standard method of LCA for all materials. To achieve a common approach to allocation, wherever physical data are available to divide between two processes, then this information will be used to allocate between multi-product processes. However, where physical data are not known, there is a requirement for a further method that can be applied to all materials. It is not possible to use system expansion for all materials because the by-products would then be subject to the same substitution criteria as the main product and this does not apply to all materials. BRE consider economic value to be a fair and appropriate method of allocation which can be applied consistently to all materials where avoidance or allocation by physical property cannot be applied. Therefore, where two product streams come from a single process (or inseparable parallel processes), and physical data are not available, BRE will allocate burdens according to the proportion of product revenue earned from the two product streams. This rule is justified because the producer has invested in setting up the process(es) and expects to earn revenues from the product streams. Accordingly the value of the product streams is considered the most appropriate basis for allocation since it assigns the burdens in proportion to the product stream’s contribution to profits arising from the process(es).iv Transport Having produced results for the kg CO2 eq.(100 years) and the Ecopoints associated with the product phases of extraction, processing and production, the relative environmental importance of transport can be compared to these. For aggregates, transport has a significant influence on the overall environmental performance of the product and therefore received a thorough transport sensitivity appraisal. The Sections on asphalt and ready mix concrete also have text on the relevance of transport, although it was found to be much less significant. For most of the other Sections, transport was not found to be a significant factor and, therefore, there is merely a note stating this with no further analysis. Case studies There is a separate section on case studies at the end of the report that looks at the difference in environmental performance between standard and good practice recycled content at a project level. Typical UK building and infrastructure constructions are considered to provide informative examples to


the reader. Where appropriate, the case studies have been scaled up to provide estimations of potential environmental impact reduction at a national level. Using New House-Building Statistics on housing starts from the National House-Building Council (NHBC), it has been possible to multiply the impact reductions by the number of buildings started in the UK in 2004v. Landfill Avoided landfill provides information on the mass of material per tonne or per m2 of specification, which has been diverted from landfill through the use of recycled raw materials in the manufacture of the specification. This has been addressed in the case studies section. As the scope increases to the national level, it must be recognised that the stated results are approximations. One of the main aims of using recycled materials is to reduce the amount of waste going to landfill. However, it should be noted that manufacturing of construction products often contributes to landfill, which is a significant environmental impact in the UK in its own right, both in terms of direct impact on the environment (e.g. through climate change emissions from landfill sites) and impact on human health. Waste to landfill is usually separated into inert materials (e.g. bricks, concrete and glass), non-hazardous materials (e.g. general household waste, timber and plastics), and hazardous materials (e.g. toxic substances and heavy metals). As the majority of landfill wastes associated with the construction products in this report can be classed as inert material, the resultant landfill savings are not separated into the above categories. They are instead looked at purely on a total mass savings basis. BRE have reviewed landfill data for construction manufacturing processes and have found that the associated landfill is not significant in comparison to the avoided landfill from using recycled input. Therefore, only figures for avoided landfill from the use of recycled input have been provided. Data gaps Data gaps are highlighted at the end of the report to aid future research and highlight the areas which would benefit from greater data capture. However, where appropriate, data gaps are mentioned throughout the report in the Quick Win category sections.

How to use this report Each product section begins with a table (see example below) that provides information on the recycled content levels for standard and good practice in that product (and revised figures if applicable taking into account the most current thinking); the recycled materials considered in the product section; and other relevant information, such as conventional virgin materials or other recycled materials that can be used but have not been considered. Each section is then split into:

a summary statement of findings; a description of product background; a discussion of recycled content; an explanation of the analytical approach and data used; the environmental impact – analysis and observation; and a section on transport where it has been shown to be significant.


The case studies section at the end of the report also incorporates an analysis of potential diversion from landfill. Finally, conclusions and recommendations are made at the end of the report. The ‘environmental impact - analysis and observation’ Section presents the environmental impact results in graph format (see Figure example 2 below). For most product Sections, industry data sets have been used. These are confidential and commercially sensitive and for this reason only general trends and observations can be made. Figure example 1 below shows how a general environmental performance trend, in this case measured in kg CO2 eq. (100 yrs), is produced from the discrete data sets used. The trend line is calculated as the “best fit” straight line through the data points. It is evident that the same or a similar general trend line could be produced by a different pattern of data sets on the graph. This highlights the fact that the trends are only indicative and cannot be regarded as either absolute or specific to all individual examples of a product type. It is apparent that, in various product categories, the environmental impact of competing brands with the same recycled content can vary significantly, depending for example on the efficiency of the manufacturing plant. Therefore the best performing brands (in terms of environmental impact) at low and high recycled content may substantially out-perform the “best fit” trend line, and vice versa. Figure example 2 presents the data in the format used throughout the report with the discrete data set points removed. Ranges and groupings of performance are also shown: a green arrow for products with no recycled content and green areas that show groupings of data sets above zero recycled content. In other Sections (aggregates, ready-mix concrete), generic industry data on the environmental impacts of extraction of materials, processing and production activities have been used but actual industry data sets for specific products have not been used. Instead, using the generic data as the foundation, the products have been “designed”, informed by dialogue with industry on the most likely materials that would be used to create the relevant products at standard and good practice recycled content. Note: Some product Sections, such as aggregates, have additional explanatory graphs and sub-sections. Example of table at beginning of each section:

Product category name

Recycled content levels

Existing Revised

% by mass

Application

Standard Good Standard Good

Example product 0 50 0 60

Recycled content materials considered Aggregate Cementitious material RCA PFA PFA GGBS

Other information…


Example of carbon emissions trend using discrete industry data sets: Figure example 1: Not presented in report (with discrete data sets visible)

Data sets create general trends

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% recycled content

kg C

O2

eq 1

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ears

Use of recycle agg

Good practiceStandard practice

No recycled content

Use of recycle agg

General trend line

Figure example 2: Presented in report (without discrete data sets visible)

Data sets create general trends

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General trend line


2 Recycled content Quick Win categories

This report addresses the fourteen Quick Win categories that have been identified by WRAP from case study evidence, including five that are concrete products. Due to a commonality of issues across the concrete product categories, they have been enveloped within an overarching Section on concrete products. This is sub-divided further into the concrete product types to provide the same level of detail that is given to the other non-concrete Quick Win categories. The Quick Win Categories considered are:

Aggregates Asphalt Ready mix concrete (RMC) Precast concrete paving Dense concrete blocks Lightweight concrete blocks Concrete roof tiles Clay facing bricks Plasterboard Chipboard Thermal insulation Ceiling tiles Floor coverings Drainage products


2.1 Unbound aggregates Table 2.1.1: Aggregate recycled content levels

Existing Revised

% by mass

Application


Granular fillvi 0 25 0 100 Pipe beddingvii 0 50 0 100 Sub-baseviii 0 100 - -

Primary materials considered with no recycled content Aggregate Crushed primary rock aggregate (sandstone, limestone, hard rock) Gravel (pipe bedding only)

Recycled content resources for the production of aggregates Aggregate Aggregate from construction and demolition waste (CDW) from off-site processing

Other recycled content resources for the production of aggregates Aggregate or aggregate resource Aggregate from construction and demolition waste (CDW) from on-site processing China clay waste Pulverised fuel ash (PFA) Asphalt planings Shales and clays Colliery spoil Waste glass cullet Municipal incinerator bottom ash Spent foundry sand Used tyres Spent railway track ballast Fired ceramic waste Slate waste

Product background

Aggregates provide the greatest opportunity for the use of recycled material in construction due to the sheer volume they represent of all construction materials used in the UK. Aggregates make up over 50% of all construction materials by weight in the UK, equating to some 240 million tonnes per year.ix They are used in numerous applications and are an integral component of most concrete products, which form one of the most significant construction material categories. There are hundreds of aggregate quarries and operations around the UK providing aggregates from sedimentary rocks (such as limestone and sandstone) and igneous rock (mainly granite), to land won and marine dredged sand and gravel. There are also hundreds of fixed and mobile crushers located around the country for producing recycled aggregates from waste materials. Some local authority district areas have no authorised crushers; however, the majority have between one and five and some areas have as many as ten or more.x


Statistics on aggregate use include 46% of primary aggregates used in unbound applications, 44% in concrete products and mortar and 10% in asphalts. The latter two applications are considered in later sections within this report and, therefore, this section is focussed on unbound applications, of which granular fill, pipe bedding and sub-base are considered to be the most significant. Furthermore, 93% of recycled aggregates are used in unbound applications (figures from communication with WRAP, November 2006). Virgin aggregate The primary aggregates considered for the three applications addressed in this Section are the most common types of crushed rock used in the UK (sandstone, limestone, and hard rock including granite) for granular fill and sub-base, and primarily gravel but also crushed rock for pipe-bedding. Recycled content The previously published levels of recycled content for standard and good practice for granular fill and pipe bedding of 0% and 25% respectively have been revised in recognition that it is more likely that a site contractor will either specify recycled aggregate or primary aggregate rather than choose a mixture of the two. This rule was already applied to sub-bases and therefore it is now the case that standard and good practice are considered to be 0% and 100% for all three aggregate applications. (The 25% figure indicates the approximate national average use of recycled aggregates – but contractors do not commonly use a 25% mix. Some mixes are available on the market, but the use of a 100% recycled or 100% primary product would be more common.) Analytical approach and data used Despite the fact that recycled aggregate can be produced from many different sources, of which a great number are listed in Table 2.1.1 above, the majority of recycled aggregate in the UK is produced by processing construction and demolition waste (CDW). In 2003, estimated waste arisings of inert construction and demolition and excavation waste in England alone were around 90m tonnes, of which around 40m tonnes were processed into aggregates, the main applications being granular fill, capping and sub-base in civil engineering.xi These 40m tonnes represent approximately 60% of all secondary aggregates used in the UK.xii The focus of this study is on aggregates from CDW and the lesser recycled aggregates in terms of usage are considered to be outside the scope of the current study, but it is an area that would benefit from more detailed study in the future. It would be a momentous task to collect the necessary data to produce environmental profiles and LCA from all of the locations where CDW is recycled for use as aggregate. Also, BRE have found that in many cases recycling operations, both on-site and off-site, have limited records on both material inputs and outputs and energy consumption on-site. To overcome this problem, BRE have worked with the Quarry Products Association (QPA) to collect data from a cross-section of recycling plants with large outputs that do have adequate records. To produce recycled aggregate, impurities, such as timber and plasterboard, are removed from CDW and the remaining material is cleaned and suitably graded. Once the materials have been separated in this fashion, a significant proportion of the resultant hard material can be used as aggregate with no further processing. For the larger pieces of hard material, such as concrete sections, crushing is necessary to produce the correct size and shape of aggregate. BRE have recognised on-site recycling of CDW as a data gap in the current project and as a result the principal comparison here is limited to primary aggregate and aggregate from off-site recycling. BRE have collaborated with the QPA and its members to collect data on the production of aggregates from the off-site processing of CDW and the results of this work have been compared to an existing body of environmental profile data on primary aggregates that was collected in 2001. Therefore, the recycled aggregates data are more recent and there may have been changes in the production of primary aggregates over the last five years that would affect the primary aggregate profiles. Despite this, BRE do not expect any changes to be major.


The BRE Environmental Profiles methodology sets a series of reasoned boundaries for the allocation of impacts depending on the nature of the materials it analyses and their respective processes. Through this process, the use of explosives in primary aggregate quarrying has been excluded from the profile for the following reasons. Existing European data that was referred to suggests that explosives are insignificant both in volume terms and their climate change impact compared to the use of diesel and electricity in quarries. However, more detailed research into the production and use of explosives in the UK would be valuable for future studies of this type. The upstream impacts associated with the original production of construction materials and demolition of those same materials producing CDW were also not included. BRE’s methodology only allocates upstream impacts to waste materials if they have a value. For example, scrap metals, which have a value, are apportioned a percentage of the impacts of the original production of the previous metal products from which they came, based on their value as scrap relative to the value of the original metal products. Also where it is seen to be significant, the impact of recapturing of the metal, for example from reinforced concrete, is also taken into account. These upstream impacts are then added to the impacts associated with the actual recycling of the scrap metals into new metal products. This has not been the case for recycled aggregates as their impacts solely come from the processing of CDW into useable aggregate product. The lists below provide an overview of the activities that are taken into account in the environmental profiles produced in this section. Crushed rock

Overburden strip Drilling Loading and transportation of exploded rock to primary crusher Crushing and screening Transfer to stockpiles Loading from stockpiles Restoration of extraction site will have been considered if the activity had occurred during the

twelve month period over which production data at the sites was collected. Activities not considered: Blasting using explosives. Gravel Land-won (85% of all gravel aggregates in the UK):

Overburden strip Extraction and transportation to washing plant Washing and screening Crushing of oversize gravel Transfer to stockpiles Loading from stockpiles Restoration of extraction site will have been considered if the activity had occurred during the

twelve month period over which production data at the sites was collected. Marine-dredged (15% of all gravel aggregates in the UK):

Dredger movement Marine dredging Transportation to washing plant Washing and screening Crushing of oversize gravel Transfer to stockpiles Loading from stockpiles


Recycled aggregate from CDW

Loading and transportation to screen Screening Crushing of oversize hard material (concrete, brick etc) Transfer to stockpiles Loading from stockpiles

The environmental impact – analysis and observations From analysing the data for all sites, both primary and recycled aggregate, it was evident that there were significant differences in the kg CO2 eq.(100 years) and Ecopoint results for the different plants. It was found that, for the production of the same type of aggregate, commonly up to twice as many kg CO2 eq. (100 years) or Ecopoints could result per tonne of aggregate at one site compared to the same type of aggregate at another site. The variance was greatest for gravel where three times as many kg CO2 eq. (100 years) and Ecopoints resulted from the worst performing site than the best performing. (Note that this analysis excludes transport-related CO2 emissions for delivery to site – which are considered separately later.)


Figure 2.1.1: Recycled content of granular fill and sub-base vs kg CO2 eq.(100 years)

Granular fill and sub-base

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0 20 40 60 80 100

% Recycled content

kg C

O2

equi

v

Crushed primary rock – average &

range

Aggregate from CDW – average

& range


Figure 2.1.2: Recycled content of pipe bedding vs kg CO2 eq.(100 years)

Pipe bedding

0

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0 20 40 60 80 100

% recycled content

kg C

O2

equi

v

Crushed primary rock & gravel –

average & range


& range



When comparing the range of results for the primary aggregate plants against the range of results for the recycled aggregate plants, it was found that in kg CO2 eq. (100 years) terms there was significant cross-over. It was also found that the average recycled aggregate was responsible for greater kg CO2 eq. (100 years) emissions than the average primary aggregate. In the case of granular fill and sub-base, where the average primary crushed rock was compared to an average recycled aggregate from CDW, the latter was responsible for 1.5 times as many kg CO2 eq.(100 years) emissions. For pipe-bedding, where the average primary aggregate of gravel and crushed rock was compared to the average recycled aggregate from CDW, this was slightly reduced to 1.44 times as many kg CO2 equiv

(100 yrs) emissions. However, it was also found that the best performing recycled aggregate for granular fill was roughly equivalent to the best performing primary aggregate in kg CO2 eq.(100 years) terms. This means that the worst performing recycling plants are raising the average but also implies that significant improvements in the efficiency of producing recycled aggregates may be possible at some plants. To better appreciate at which stages of the recycling process the potential improvements in efficiency could be made will require a separation of the impacts according to each processing stage. This study has used overarching data that rolls all the stages into one and has therefore not been able to achieve this. However, WRAP has recently commissioned a more detailed study. The kg CO2 eq.(100 years) emissions results suggest that greater energy efficiencies are achieved at primary aggregate plants than recycled aggregate plants. However, it would advisable for metering of the different machinery employed for both types of aggregate production to identify more precisely the efficiencies achieved in practice and also to see which parts of the process are responsible for most emissions. In principle, it might be expected that aggregate recycling would require less of the energy-intensive crushing process than the same quantity of crushed rock, leading to a lower carbon impact – but energy demand may also vary with the scale of production. However, it must be noted that it is possible to source recycled aggregates that have lower embodied kg CO2 eq. (100 years) than some primary aggregates. Furthermore, an important consideration is that of the transport of aggregates, which is considered in a sub-section below.


Figure 2.1.3: Recycled content of granular fill vs Ecopoints


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Ecop

oint

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rangeAggregate from CDW – average

& range


Figure 2.1.4: Recycled content of pipe bedding vs Ecopoints

Pipe bedding

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Crushed primary rock & gravel –

average & rangeAggregate from CDW – average

& range


On an Ecopoints basis the results are very different. There is no cross-over between the range of results for recycled aggregate and the range of results for primary aggregates, with the recycled aggregates’ range being significantly below the primary aggregates’ range. Also the average recycled


aggregate has a much better Ecopoint environmental performance than the average primary aggregate. In the case of granular fill and sub-base where the average primary crushed rock was compared to an average recycled aggregate from CDW, the latter was responsible for 5.2 times fewer Ecopoints. For pipe-bedding where the average primary aggregate of gravel and crushed rock was compared to the average recycled aggregate from CDW, this slightly increased to 5.4 times fewer Ecopoints. The principal reason for this difference is the impacts associated with minerals extraction, which accounts for between 34% and 38% of the impacts for all the sites analysed. Transport Unlike in many of the other product categories, the distance aggregate is transported can have a significant impact on the environmental performance of the delivered aggregate. This sub-section acts as a transport sensitivity analysis of the impacts of transporting aggregates and looks at them in light of the difference in Ecopoint and kg CO2 eq.(100 years) scores between standard and good practice recycled content. Primary aggregates have little if no transport from the quarry to the processing plant, which are almost always adjacent to each other. The transport over this distance is accounted for within the data on mobile machinery usage that takes place in the quarries and their processing plants. The average transport distance of the CDW considered within the report to the recycling plants was found to be 23.4km and the loads ranged from between 10 to 18 tonnes with the average load being 14 tonnes. The impacts of this transport are factored into the cradle to factory gate environmental performance for recycled aggregate. However, up to this point, transport beyond the factory gate has not been considered for either primary or recycled aggregate. The following analysis looks at the relative transport impact of aggregate freight transport by road, rail and ship. The approach equates the differences in environmental performances indicators, kg CO2 eq. (100 years) and Ecopoints, to a transport distance for the modes of transport aforementioned. There is also an additional section that looks at on-site recycling; however, as no data were collected on on-site recycling, the data from off-site recycling have been used as a proxy with the transport of the CDW subtracted. In the light of this assumption, the latter analysis should be regarded as hypothetical and the findings should not be treated as absolute. Transport according to kg CO2 eq.(100 years) and Ecopoint differences between standard and good practice recycled content associated with transport to the construction site The Ecopoint and kg CO2 eq.(100 years) analyses above have demonstrated on the one hand that production of the average recycled aggregate considered is responsible for greater kg CO2 eq.(100 years) per tonne of material than production of the average primary aggregate, but on the other hand the average recycled aggregate has significantly fewer Ecopoints than the average primary aggregate. Also, it has been shown that it is possible to source a recycled aggregate with lower kg CO2 eq.(100

years) emissions than many primary aggregates. From the data used, however, it is not possible to source a primary aggregate with a lower Ecopoint score than any of the recycled aggregates considered. If one converts the kg CO2 eq.(100 years) emissions difference between the average recycled aggregate and the average primary aggregate to a transport distance, i.e. the kg CO2 eq.(100 years) emissions associated with the use of a typical aggregate lorry loaded with aggregate, the result would suggest that primary aggregate can be transported a greater distance than recycled aggregate before the same level of kg CO2 eq.(100 years) emissions are produced. For granular fill or sub-base, primary aggregate can be transported 11.4 kilometres more than a recycled aggregate and for pipe bedding 10.4 kilometres more.xiii This same exercise can be performed for the other two principal modes of transport by which aggregates are transported in the UK, by rail and by ship. The distances given for


these latter modes of transport are significantly greater due to their greater efficiencies in moving goods using less energy. Therefore, on a carbon emissions basis, for off-site recycled aggregate to be preferable in terms of lower carbon emissions, the following criteria apply for granular fill and sub-base:

Mode of transport of primary aggregate

Maximum additional transport distance of primary aggregate relative to recycled aggregate (from processing plant to construction site) (km)

Road 11 Rail 64 Ship 241

And for pipe bedding:


Maximum additional transport distance of primary aggregate relative to recycled aggregate (from processing plant to construction site) (km)


Note: if the transport of primary aggregate is by rail and road, or ship and road to reach the construction site, the maximum rail and shipping distances for carbon equivalence are smaller. Conversely, if one converts the Ecopoint difference found between primary and recycled aggregates, one could equally justify transporting the recycled aggregate (by road) 227 kilometres for granular fill and sub-base and 234 kilometres for pipe bedding more than the primary aggregate equivalent. Therefore, for primary aggregate to be preferable in terms of lower Ecopoints, the following criteria apply (for granular fill and sub-base):


Minimum cut in transport distance of primary aggregate relative to recycled aggregate (from processing plant to construction site) (km)






These figures need to be put into the context of likely distances that primary aggregates and recycled aggregates are transported. If primary aggregate is transported 40km by road to the construction site on average (national average quoted by the British Geological Survey), secondary aggregate should be sourced within about 30km by road on average to avoid an increase in overall carbon emissions,


but could be sourced up to 260km away by road without increasing Ecopoints. In practice, however, recycled aggregate is typically sourced within close proximity of a construction site – hauling primary aggregate by road for more than ~50km typically becomes uneconomic, and the economic transport distance for a lower-value recycled aggregate will be even less. (Typical client requirements for recycled content do not lead to recycled content being used where it increases total materials costs after taking transport costs into account.)

Hypothetical on-site recycling compared to primary aggregate provision The following discussion is premised on the assumption that subtracting the transport impacts associated with off-site production of recycled aggregate (i.e. subtracting the transport of CDW from a construction/demolition site to the reprocessing plant) gives a set of remaining impacts that are equivalent to those of on-site production of recycled aggregate. By doing this the performance of recycled aggregate is found to be even better in Ecopoint terms as one might expect, but also it has improved sufficiently enough in kg CO2 eq.(100 years) terms for the on-site recycling to be better than supplying primary aggregate; this is the case for granular fill, sub-base and pipe bedding. Therefore, on average and based on the assumption that on-site recycling plant has the same impact as off-site recycling plant, the data imply that:

reuse on site of aggregate arising and reprocessed on the same site is preferable, in terms of both carbon and Ecopoints, than primary aggregate, regardless of transport mode; and

reuse elsewhere (i.e. off-site) of aggregate reprocessed on the demolition site has a carbon and Ecopoints advantage over primary aggregate at equal transport distance.

Therefore, for primary aggregate to be preferable in terms of lower carbon emissions than aggregate reprocessed on the demolition site and supplied for use at another construction site, the following criteria apply for granular fill and sub-base:








And for primary aggregate to be preferable in terms of lower Ecopoints, the following criteria apply for granular fill and sub-base:









As mentioned above some significant assumptions have been made in this final analysis and therefore BRE advise that more rigorous research is conducting specific to on-site recycling, both in terms of how much on-site recycling takes place and direct measurement of the energy consumption of on-site recycling machinery and the resultant environmental impacts.


2.2 Asphalt paving (ex-situ)

Table 2.2.1: Asphalt recycled content levels Existing Revised

% by mass

Application


Ex-situ asphalt paving 10 15 0 14

Virgin materials Aggregate Binder Crushed primary rock Bitumen Gravel Sand

Recycled content materials considered Aggregate Recycled asphalt planings (RAP)

Statement of findings There were significant data gaps in the analysis of asphalt options meaning that overarching statements can not be made without the potential for them to be misleading and unwarranted. Firstly, the information available on the energy consumption of cold and hot processing machinery was not sufficiently robust to incorporate, therefore it was not possible to compare these different asphalting techniques with a sufficient degree of confidence in the results. It is an area where greater research and possible metering would be beneficial. Secondly, warm processing and in-situ asphalt recycling have not been considered. The latter of these would be particularly valuable to the debate, however, it was not possible to obtain good measurements on the relevant consumption of water and energy of the machinery. Therefore, the remaining analysis has considered ex-situ asphalt production at standard and good practice level, in which the laying process can be considered to be the same for both. Product background The term asphalt is commonly used to refer to asphalt concrete, which can be applied hot, warm or cold. “Asphalt” itself is almost entirely composed of bitumen, a semi-solid material present in most crude oils. Asphalt concrete like cement concrete requires an aggregate material and a binder, and it is the asphalt itself that performs this latter function in the same way that cement does in conventional concrete. Asphalt concrete is commonly used for construction of pavement, highways and parking lots. Asphalt design is dictated by the forces that it will be subjected to in-service and for this reason, asphalt surfaces that are going to support heavy goods vehicles have a higher specification and greater thickness than asphalt surfaces that are subjected to lighter loads. However, generally speaking most asphalt pavements have an unbound sub-base, and base, of crushed rock aggregate and two bitumen-bound asphalt layers consisting of a binder course and surface course; the base can also be installed with a binder component depending on conditions and requirements. The aggregate size generally decreases as one moves up the layers. In the asphalt concrete mix, the aggregate is


roughly split into two portions, coarse aggregate and fine aggregate, provided by primary crushed rock (listed above) or gravel, and sand respectively. Recycled content Whilst BRE recognise that the published standard practice (10%) and good practice (15%) recycled content figures are likely to be representative of many examples of asphalt paving in the UK, through consultation with asphalt and aggregate suppliers it is evident that the recycled content is process specific, therefore the recycled material used and the level used that is commonly achievable for hot laying of asphalt may not be applicable to warm or cold laying of asphalt. Industry steer suggested that around 14% is a fair representation of good practice recycled content. Also asphalt paving with no recycled content was felt to be still commonplace and more representative of standard practice than the previously published 10%. In consequence the figures have been revised in Table 2.2.1. Asphalt specifications can vary significantly according to the end use and the loads the pavement is expected to support. Also asphalt specifications can vary depending on Local Authorities’ requirements, as different authorities often produce their own set of standards for public paving areas that must be complied with. For the purposes of this analysis, asphalt paving for light and medium weight traffic with a total depth of 300mm (40mm surface course, 60mm binder course, 100mm base course and 100mm sub-base course) has been considered. The overall material composition for the different practices is presented in Table 2.2.2 below. Through dialogue with the asphalt paving industry these are felt to be fair representations of the likely material breakdowns of the two paving compositions considered. Table 2.2.2: Asphalt paving material compositions

Recycled

content (%) Bitumen Crushed rock RAP*

Standard practice ex-situ asphalt 0 3.42% 96.58%

Good practice ex-situ asphalt 14 3.42% 82.87% 13.71%

RAP is made from asphalt concrete that is removed from a road or pavement. Referred to as “road planings”, this material requires processing but according to findings of research conducted with the QPA the processing in question requires significantly less energy than either primary aggregate or recycled aggregate provision. The majority of road planings taken up from roads in the UK (6 million tonnes in 2004) are processed and reused, with only 10% going to landfill.xiv They are usually taken to an asphalt recycling plant (ex-situ) and processed into recycled asphalt product before being returned and used in base and binder courses.

Analytical approach and data used The environmental impacts associated with the materials considered in this section are sourced from BRE’s database of environmental impacts of materials and existing and new data on recycled aggregate and recycled asphalt product from industry. Currently BRE are working with the QPA to produce more up-to-date data on the environmental impacts on primary aggregates and it was hoped that the results of the work would be ready for incorporation into this current report. However, the results were not ready in time and therefore existing data have been used. The environmental impact – analysis and observations The results found that moving from standard to good practice recycled content produced benefits in both reducing kg CO2 eq.(100 yrs) emissions and reducing Ecopoints. Although bitumen has a very high

* Recycled asphalt planings


carbon footprint, the bitumen content of the two different asphalt paving options does not vary and therefore the reduction in carbon emissions cannot be attributed to a reduction in bitumen. The cause of the improvement is wholly because of the reduction in use of primary aggregate from approximately 97% to approximately 83%, replacing the difference with recycled asphalt planings (RAP). The industry production data on the collection and processing of RAP demonstrated that the RAP had no associated cost to the receiving processing plant. Therefore, in line with BRE’s Environmental Profiles Methodology, which allocates upstream environmental impacts to wastes that are reused according to their value, there are no such impacts embodied by the RAP used in good practice recycled asphalt paving. Consequentially, replacing primary aggregate, which does have environmental burdens, will lead to a positive environmental benefit across all environmental impact categories considered, including carbon emissions. As the dominant impact category for primary aggregates is minerals extraction, the greatest environmental performance improvement can be attributed to minerals extraction no longer being an issue through the use of RAP. Figures 2.2.1 and 2.2.2 illustrate the level of improvement engendered by the change in practice in kg CO2 eq. (100 years) emissions and Ecopoint performance respectively. Figure 2.2.1: Recycled content of asphalt paving vs kg CO2 eq. (100 years)

Asphalt paving

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% recycled content

kg C

O2

equi

v


No recycled content

14% RAP


Figure 2.2.2: Recycled content of asphalt paving vs Ecopoints

Asphalt paving

0.9

1

1.1

1.2

1.3

0 2 4 6 8 10 12 14 16

% recycled content

Ecop

oint

s


No recycled content

14% RAP

Transport Transport could have a significant impact on the environmental performance of asphalt paving. However, an in-depth transport analysis has been prevented by the low level of data available for asphalt and its different modes of application. Also, a comparison of on-site and ex-situ asphalt laying would be a valuable objective of future research of this kind. Both transport of materials to the asphalt processing plant and transport of the final product from the plant to the point of use would benefit from further analysis. The current assumptions for these are as follows: Firstly, regarding transport to the plant, in the preceding analysis it has been assumed that the primary aggregate and the RAP used in the asphalt specifications have been transported the same distance. The indication from the data sets used for the analysis of asphalt suggest that the RAP is transported a longer distance to the processing plant than primary aggregates and therefore incurs greater transport impacts. However, as only a small number of data sets were available for the analysis the transport distances given by them cannot be held as wholly representative of the national situation. National data on the transport of RAP should be incorporated into future research. Secondly, regarding the transport from the plant gate to site, both the asphalt pavings considered are assumed to be from an ex-situ asphalt plant therefore the transport of the asphalt to the point of use will be the same for both types and therefore there will no difference in environmental performance as a result of transport. The asphalt plants that provided data for this study are able to produce asphalt using both RAP and primary aggregate, which supports the assumption above. However, there may be instances at a national level where some plants are more likely to process RAP than others. If this is the case, the distances to the point of use may be an important aspect that needs greater consideration.


2.3 Ready-mix concrete (RMC) Table 2.3.1: RMC recycled content levels

Existing Revised

% by mass

Application


RMC up to C25 0 24 - -

RMC above C25 0 7 - -

Recycled content materials considered Aggregate Cementitious material RCA PFA BFS GGBS China clay waste

Statement of findings Moving from standard practice to good practice in all ready-mix concretes (RMC) has environmental benefits on the basis of both kg CO2 eq.(100 years) and Ecopoints. This is not due to the use of recycled aggregate but a consequence of reducing the cement content by using GGBS or PFA as a cement replacement. Product background

Ready-mixed concrete is manufactured in over 1300 plants across the UK and then transported to construction sites in trucks with rotating barrels that are a common sight on roads in the UK. According to the British Ready Mix Concrete Association (BRMCA), the average delivery distance is less than 48km. The product is poured into purpose-made moulds (formwork) to create the required building element.

Recycled content The recycled content levels published by WRAP are in accordance with BRE’s current research and dialogue with industry.

Most reinforcement bars (rebar) used in the UK are ~100% recycled steel, therefore, there is next to no room for increasing the recycled content of the reinforcement component of structural RMC. For this reason, the rebar is excluded in the recycled content of RMC in this Section.

Approximately 20% recycled content can easily be achieved through the use of recycled aggregate in lower-strength concretes. The remaining 4% required to achieve the 24% recycled content at good practice can be achieved with the additional inclusion of cement replacement material, such as PFA and GGBS. While it is technically possible to use a high proportion of RCA in higher-strength concrete mixes (i.e. as 100% of the aggregate component), the RCA needs to be of an exceptionally high purity. In line with BS 8500 up to 20% of the aggregates in a RC40 concrete can be RCA; however, there are currently significant supply barriers associated with the use of RCA for structural concrete. For this


reason, good practice is currently much more likely to be closer to the published 7% recycled content at good practice, which will use PFA or GGBS as cement replacement.

Contractors (and developers) are currently very hesitant to specify recycled aggregates for concretes above C30 strength because of concerns regarding the consistency and reliability of the feedstock. Similarly concrete contractors are hesitant to supply concrete containing RCA for structural purposes because of complexities in securing a supply of an appropriate feedstock of known quality, and practically because they do not have space at their batching plants to locate a separate aggregates bin for RCA. These concerns could be alleviated if the developer could provide a source of known quality recycled concrete aggregate (e.g. derived from demolition and processing of an existing building or from a consistent material type such as railway sleepers) although this would require extensive testing before it could be used for structural concrete. Analytical approach and data used The kg CO2 eq.(100 years) and Ecopoint results for RMC have been produced using mix designs recognised by industry as likely current practice at standard and good practice recycled content assuming that the recycled material used has the same performance characteristics and behavioural properties as conventional virgin alternatives. Additionally, data on related extraction, processing and production impacts were sourced from the relevant industrial sectors (quarrying, cement, ash and RMC production itself) for the publication of BRE’s Green Guide to Housing Specification in 2000. Therefore, it must be recognised that whilst the RMC mix design reflects actuality, the LCA data are six years old and industry practice may have changed over this time.

The environmental impact – analysis and observations RMC up to C25 Moving from standard to good practice recycled content in RMC up to C25 produces an environmental benefit both in terms of kg CO2 eq.(100 years) and Ecopoints (see Figures 2.3.1 and 2.3.2). The similar pattern of improved environmental performance for these environmental performance metrics is due to the climate change impact (kg CO2 eq.(100 years)) being the most significant environmental impact within the Ecopoints results. This is a consequence of cement having by far and away the greatest impact of the input materials. Therefore, most of the improvement in environmental performance is not due to the use of recycled aggregates, but instead it is the slight reduction in cement used by using 4% GGBS or PFA that creates the improvement. The RMCs that use GGBS perform better than those that use PFA because GGBS as a cement replacement allows for a slightly greater reduction in cement content.


Figure 2.3.3: Recycled content of RMC up to C25 vs kg CO2 eq. (100 years)

Upto C25 RMC

80

85

90

95

100

105

110

115

120

125

130

0 5 10 15 20 25 30 35 40

Recycled content %

kg C

O2

equi

vale

nt p

er to

nne

No recycled content

PFA & BFS

PFA & china clay waste

GGBS & BFS

GGBS & RCA

GGBS & china clay waste

PFA & RCA

General trend line


Figure 2.3.4: Recycled content of RMCs up to C25 vs Ecopoints

Upto C25 RMC

0.8

0.9

1

1.1

1.2

1.3

1.4

0 10 20 30 40

Recycled content %

Ecop

oint

per

tonn

e

No recycled content

PFA & BFS

PFA & china clay waste

GGBS & BFS

GGBS & RCA

GGBS & china clay waste

PFA & RCA

General trend line



RMC above C25 For RMC above C25, moving from standard to good practice recycled content has environmental benefits in terms of both kg CO2 eq.(100 years) and Ecopoints. However, in the case of the higher strength concretes the level of improved benefits is more significant. This is a consequence of not using recycled aggregates, which have a worse environmental impact in kg CO2 eq. (100 years) terms than the average virgin aggregate. Also using GGBS allows for a slightly greater reduction in cement content, thereby providing better environmental performance than a RMC using PFA as a cement replacement.

Figure 2.3.5: Recycled content of RMCs above C25 vs kg CO2 eq. (100 years)

RMCs above C25 - C30 as benchmark

80

90

100

110

120

130

140

150

160

0 2 4 6 8 10

Recycled content %

kg C

O2

equi

vale

nt p

er to

nne

No recycled content

PFA

GGBS

General trend line



Figure 2.3.6: Recycled content of RMC above C25 vs Ecopoints

RMCs above C25 - C30 as benchmark

1

1.1

1.2

1.3

1.4

1.5

1.6

0 2 4 6 8 10

Recycled content %

Ecop

oint

per

tonn

e

No recycled content

General trend line

PFAGGBS


Transport The proportion of the total environmental impacts that transport of materials used in RMC represents is small. This is a consequence of the overriding impacts associated with cement production. For this reason in the UK transport of RMC in terms of kg CO2 eq.(100 years) is typically less than 1% of the total kg CO2 eq.(100 years) emissions associated with RMC. On the basis of this, it can be suggested that transporting recycled or primary materials greater distances would make little difference in the case of RMC. However, there are availability and cost issues that limit what can and cannot be transported greater distances. Most of the cement replacement materials, PFA and GGBS, are utilised close to the point of source and transporting these and the recycled aggregates would have cost implications and would dissolve the cost neutrality that is recognised between standard and good practice. Therefore it is unlikely that significant differences in transport distance and associated environmental impact would arise.


2.4 Precast concrete paving

Table 2.4.1: Precast concrete paving recycled content levels Existing Revised

% by mass

Application

Standard Good Standard Good Concrete paving blocks 5 50 - -

Concrete reconstituted stone paving blocks 5 40 - -

Concrete paving slabs (flags) 3 20 - -

Virgin materials considered Aggregate Sand Gravel

Recycled content resources for the production of aggregates and cement replacement Aggregate resources Cement replacement material RCA PFA China clay waste GGBS

Statement of findings Environmental improvements in terms of Ecopoints can be achieved by moving from standard to good practice recycled content in all paving products. For concrete paving slabs there is also a potential benefit in reducing associated kg CO2 eq.(100 years) emissions. This secondary benefit occurs due to the possibility of reducing the cement content by adopting good practice. However, increased recycled content has a marginal disbenefit in kg CO2 eq.(100 years) for both concrete block paving types. This is because increasing recycled content in concrete block paving is unlikely to produce reductions in cement content. Instead the shift represents the modelled impact of the replacement of virgin aggregate materials with recycled aggregate materials which, as a generic trend through available data, have a greater kg CO2 eq.(100 years) burden than virgin aggregates. Product background Paving products were introduced to the UK in the 1970s and are now used for surfaces that accommodate pedestrian, car and heavy vehicle traffic. For the purpose of this report paving products have been separated into concrete paving slabs (flags) and concrete paving blocks. The latter category is divided again into concrete paving blocks and concrete reconstituted stone paving blocks. Concrete paving slabs differ from concrete block paving (CBP) in their larger dimensions, slight difference in material composition and their production process. Concrete paving slabs are almost always wet-pressed whereas concrete blocks can be wet-pressed and cut into shape but are usually formed using a semi-dry process. Additionally, concrete block paving is used for pedestrian, car and heavy goods vehicle traffic whilst concrete paving slabs are more commonly used for pedestrian and car traffic, with only the occasional possibility of heavy goods vehicle movement.


Recycled content Dialogue with industry suggests that china clay waste can be used as a recycled aggregate in paving products, and PFA and GGBS can be used as a recycled cement replacement. Primary aggregate (mainly limestone, granite and sandstone) fines from quarrying can also be used in concrete reconstituted paving blocks, however, they are not classified as recycled content. Specified at 5mm and 10mm, these smaller aggregate materials are often produced in conjunction with cut stone or larger sized aggregates; however, they are often produced in their own right. For this reason, as with other aggregates, they are subject to the Aggregates Levy. The previously published recycled content figuresxv (see table above) for concrete reconstituted block paving for standard and good practice of 5% and 40% respectively assume the use of primary aggregate fines as the recycled portion. However, dialogue with the aggregates’ industry that was undertaken as part of the research for this project suggested that primary aggregate fines should not be classed as recycled content and the previous assumption was erroneous. Nevertheless, the published figures could potentially be achieved through the combined use of china clay waste and recycled cement replacement material. However, most china clay waste is sourced from Cornwall and therefore the transport impacts associated with hauling the material to paving plants across the UK must be taken into account. The published figures (see table 2.4.1 above) for standard and good practice recycled content for concrete paving blocks and concrete paving slabs are in keeping with BRE’s current understanding of the paving market. RCA can be used in both CBP and paving slabs. However, due to the wet process used for the production of concrete paving slabs, GGBS is the most probable cement replacement and not PFA which can produce a mottling effect that is more recognisable in concrete paving slabs. The mottling effect is less problematic in concrete paving blocks and therefore PFA can also be used in this product category. China clay waste provides a likely fine aggregate substitute as the other potential recycled content in concrete block paving. There are factors that limit the level of use of recycled materials used in paving products and their uptake within industry, including issues such as aesthetic appearance, durability, curing time, water absorption, fine and organic material contamination and strength properties. However, the discussion of these is outside the scope of this report. Analytical approach and data used The kg CO2 eq.(100 years) and Ecopoint results for precast paving have been produced using mix designs recognised by industry as likely current practice at standard and good practice recycled content assuming that the recycled material used has the same performance characteristics and behavioural properties in production as conventional virgin alternatives. Additionally, data on related extraction, processing and production impacts were sourced from the relevant industrial sectors (quarrying, cement, ash and RMC production itself) for the publication of BRE’s Green Guide to Housing Specification in 2000. Therefore, it must be recognised that whilst the RMC mix design reflect actuality, the LCA data are six years old and industry practice may have changed over this time.

The environmental impact – analysis and observations Concrete block paving Moving from standard to good practice recycled content in concrete block paving slightly increases the kg CO2 eq.(100 years) result. By replacing the majority of the fine sand aggregate with china clay waste processed to the correct particle size, there is a slight increase in associated kg CO2 eq.(100 years)

(see figure 2.4.1). However, there is a reduction in the Ecopoint score, and therefore an improvement in environmental performance, when moving from the lower to the higher recycled content standard (see figure 2.4.2). This improvement is almost entirely a consequence of the reduction in minerals extraction. For the example mixes chosen, all the other component materials have been kept constant.


Figure 2.4.1: Recycled content of concrete block paving vs kg CO2 eq.(100 years)

Concrete Paving Blocks

100

105

110

115

120

125

130

0 10 20 30 40 50 60

Recycled content %

kg C

O2

equi

vale

nt p

er to

nne


5% GGBS, cement, sand

and gravel

5% GGBS, cement, 45%

china clay waste, and gravel

Figure 2.4.2: Recycled content of concrete block paving vs Ecopoints

Concrete Paving Blocks

0.8

0.9

1

1.1

1.2

1.3

0 10 20 30 40 50 60

Recycled content %

Ecop

oint

per

tonn

e


5% GGBS, cement, sand

and gravel

5% GGBS, cement, 45%

china clay waste,and gravel


Concrete reconstituted block paving As with concrete block paving, moving from standard to good practice recycled content in concrete reconstituted block paving increases the kg CO2 eq.(100 years) result (see figure 2.4.3), however, in this latter case the increase is greater due to the associated kg CO2 eq.(100 years) being greater for china clay waste relative to virgin sand. Conversely, there is a reduction in the Ecopoint score, and therefore an improvement in environmental performance, when moving from the lower to the higher recycled content standard (see figure 2.4.4). As with concrete paving blocks, the improvement in Ecopoints can largely be attributed to the reduction in minerals extraction. However, the level of improvement is less marked than in concrete paving blocks because of the greater impact of aggregate on the (higher) kg CO2 eq.(100 years). For the example mixes chosen, all the other component materials have been kept constant. Figure 2.4.3: Recycled content of concrete reconstituted block paving vs kg CO2 eq.(100

years)

Concrete Reconstituted Paving Blocks

100

105

110

115

120

125

130

0 10 20 30 40 50

Recycled content %

kg C

O2

equi

vale

nt p

er to

nne


5% aggregate fines, cement,

sand and gravel


sand and gravel


Figure 2.4.4: Recycled content of concrete reconstituted block paving vs Ecopoints

Concrete Reconstituted Paving Blocks

0.8

0.9

1

1.1

1.2

1.3

1.4

0 10 20 30 40 50

Recycled content %

Ecop

oint

per

tonn

e



sand and gravel


sand and gravel

Concrete paving slabs The results for concrete paving slabs highlight the overriding influence of cement on environmental performance in concrete products. At standard practice, 3% PFA is assumed as a cement replacement, but at good practice 6% PFA is assumed with a consequent reduction in cement content. The benefits achieved in both kg CO2 eq.(100 years) and Ecopoints as a result of this slight reduction in cement content outweigh any detriments from the replacement of virgin aggregate with recycled aggregates in kg CO2 eq.(100 years) terms. The Ecopoint improvement is even greater because of the added benefit of reducing minerals extraction.


Figure 2.4.5: Recycled content of concrete paving slabs vs kg CO2 eq.(100 years)

Concrete Paving Slabs

100

105

110

115

120

125

130

0 5 10 15 20 25

Recycled content %

kg C

O2

equi

vale

nt p

er to

nne

Good practiceStandard practice Good practiceStandard practice

3% PFA, virgin coarse and fine aggregate, and

cement

34% recycled concrete

aggregate, cement, 6% PFA

and sand

Figure 2.4.6: Recycled content of concrete paving slabs vs Ecopoints

Concrete Paving Slabs

0.8

0.9

1

1.1

1.2

1.3

1.4

0 5 10 15 20 25

Recycled content %

Ecop

oint

per

tonn

e


3% PFA, virgin coarse and fine aggregate, and

cement

34% recycled concrete

aggregate, cement, 6% PFA

and sand


Transport The environmental impacts associated with the typical transport of the paving products considered in this report were found to be insignificant compared to the overall environmental impacts. For this reason a more in-depth transport analysis has not been undertaken.


2.5 Dense blocks Table 2.5.1: Recycled content levels

Existing Revised % by mass

Application


Dense blocks 0 50 5 50 Recycled content materials considered Aggregate Cementitious material RCA PFA PFA GGBS China clay waste FBA

Other recycled content materials Aggregate Cementitious material Glass

Statement of findings In dense concrete blocks, there is a general trend for increased recycled content to have the adverse effect of increasing kg CO2 eq.(100 years) emissions but the beneficial outcome of fewer Ecopoints. This means that, as an average through the available data, higher recycled content in this product grouping performs more poorly according to the climate change metric, but better overall for all the impact metrics. However, looking beyond the general trends there is significant variance in the performance results at any given recycled content level. For example, depending on which brands are compared, blocks at good practice may have lower or higher carbon/environmental impact than blocks at standard practice. Product background There are over 50 concrete block manufacturers in the UK with over 100 concrete block plants. Concrete blocks can be used in building foundations, ground and suspended floors, and external and internal walls.

Concrete blocks offer good potential as one of the top ten contributors to higher recycled content across a range of projects (i.e. as a “Quick Win”). This is because they can potentially utilise high levels of recycled material at the point of manufacture, and because they often contribute a significant proportion of material mass to a building project. Dense concrete blocks typically include two main ingredients consisting of an aggregate and a cementitious component. Both material fractions have opportunity for substitution and the inclusion of recycled content. Industry data shows high variation in recycled content of products on the market, at between 0 and approx 90% recycled content.


Recycled content Previous work conducted by BRE on behalf of WRAP concluded that dense concrete blocks generally had 0% recycled content at standard practice, however, work conducted as part of this project indicated that a 5% figure might be more current and appropriate. The product recipe information that BRE holds indicates 0% to be a conservative estimate in recognition that the vast majority of dense blocks today appear to include some recycled content. 5% is most commonly achieved through the inclusion of FBA, PFA or GGBS as a part cement replacement. WRAP have defined good practice recycled content as 50% (Davis Langdon report for WRAP 2006) and this is commonly observed to consist of aggregate and cementitious binder replacements. BRE data generally concurs with WRAP’s assessment that 50% recycled content is good practice. This can be achieved with replacement of the primary aggregate only or replacement of both the primary aggregate and some of the cementitious material with a cement replacement. Analytical approach and data used A study undertaken in 2004 for the Concrete Block Association (CBA) has provided BRE with a detailed LCA Environmental Profile database covering 7N and 10N dense blocks. More recently BRE has also been involved in the development of a series of proprietary product LCA inventories on dense blocks. Together this information provides 25 discrete datasets. These inventories are commercially sensitive and have been supplied in confidence. Due to this sensitivity, the conclusions drawn are presented as trends and from a holistic perspective across LCA datasets.

The environmental impact – analysis and observations It was found that there was significant variation in the kg CO2 eq.(100 years) and Ecopoint results for the sites covered by the data. The size, age, machinery, fuel usage and product portfolio are some of the factors that mean that sites producing almost identical products can be responsible for significantly different environmental performance levels. The general trends show that moving from standard to good practice recycled content increases kg CO2 eq.(100 years) but decreases Ecopoints (see figures 2.5.1 and 2.5.2 respectively). Figure 2.5.1: Recycled content of dense blocks vs kg CO2 equiv (100 yrs)

Dense block

40

60

80

100

120

140

160

180

200

220

0 20 40 60 80 100

% Recycled content

kg C

O2

eq p

er m

2

Use of recycled agg

and PFA

Use of recycle agg


PFA as cement

replacementNo

recycled content


Figure 2.5.2: Recycled content of dense blocks vs Ecopoints

Dense blocks

0.4

0.9

1.4

1.9

2.4

2.9

0 20 40 60 80 100% Recycled content

Ecop

oint

s pe

r m2

Use of recycled agg

and PFA

Use of recycle agg


PFA as cement

replacement

No recycled content

The improvement in Ecopoint performance with greater recycled content is due to the reduced minerals extraction associated with the use of recycled aggregates. In contrast, the general trend for increased kg CO2 eq.(100 years) emissions with increased recycled content is explained due to the greater use of recycled aggregate, which on average has been found to have higher kg CO2 eq.(100 years) emissions, and the higher concentration of cement in some of the blocks with higher recycled content. As in most concrete products, cement dominates the environmental impacts in dense concrete blocks. Cement carries with it high embodied impacts in particular from the climate change impact category. This means as cement content increases within concrete block products, both kg CO2 eq.(100 years) emissions and Ecopoints increase as well. This trend is clearly visible in Figures 2.5.3 and 2.5.4 below. The cement content of dense concrete blocks assessed in this study is commonly around 5-7%. However, this did vary with a range of up to 9%, and as low as 4%. Evidence from this study indicates that although manufacturers are using PFA (as a cementitious component), they are not necessarily lowering the cement content as a consequence. Indeed, data show that products with zero recycled content have the lowest average cement content; and it is possible to observe a rise in cement content in products that are using recycled aggregate and PFA. BRE could distinguish no environmental advantage between products that used PFA in this way and others examined in the study. Cement concentrations in these products were elevated and the percentage PFA was too small to show any real benefit from a minerals depletion perspective.


Figure 2.5.3: Correlation between cement content and kg CO2 eq. (100 years) for all concrete block products assessed in the study

Dense blocks

0.4

50.4

100.4

150.4

200.4

250.4

0 1 2 3 4 5 6 7 8 9 10

% Cement content

kg C

O2

equi

v pe

r m2

Figure 2.5.4: Correlation between cement content and Ecopoints for all concrete block products assessed in the study

Dense blocks

0.4

0.6

0.8

1

1.2

1.4

1.6

0 1 2 3 4 5 6 7 8 9 10

% Cement content

Eco

poin

ts p

er m

2

Transport The environmental impacts associated with the typical transport of the dense concrete block products considered in this report were found to be insignificant compared to the overall environmental impacts. For this reason a more in-depth transport analysis has not been undertaken.


2.6 Lightweight blocks Table 2.6.1: Lightweight blocks recycled content levels

Existing Revised

% by mass

Application


Lightweight blocks 50 60 50 80

Virgin materials considered Aggregate Crushed rock Gravel

Recycled content resources for the production of aggregates and cement replacement Aggregate resources Cementitious material RCA PFA PFA GGBS China clay waste FBA

Statement of findings For lightweight blocks, increasing recycled content from standard (50%) to good practice (80%) produces no explicit improvement in kg CO2 eq.(100 years) environmental performance (see figure 2.6.2). However, there is an improvement in the Ecopoint environmental performance from standard to good practice, reducing the Ecopoints by approximately 15% on average (see figure 2.6.3). Product background Lightweight blocks consist of a lightweight coarse aggregate, a fine aggregate and cementitious material. The aggregates can be composed of recycled content in their entirety whereas the cementitious material always requires some virgin cement to achieve the necessary strength characteristics; recycled cementitious materials alone are not sufficient. PFA can be used as both a lightweight aggregate and a cementitious material, although the latter requires grinding into a fine powder and therefore has a higher embodied energy and associated kg CO2 eq.(100 years) as a result. 100% of the FBA produced in the UK is sold and used mainly as a coarse aggregate in lightweight concrete blocks. Recycled content In 2004, BRE recognised standard and good practice levels of recycled content in lightweight blocks as 50 and 60% respectively (BRE report for WRAP 2004). However, since then, work by Davis Langdon suggests that the good level of recycled content could be higher and maybe as much as 80% in some cases. Best practice was previously 80% but in recognition of products now on the market at over 90%, a higher figure here is likely to be more appropriate. Achieving such high levels of recycled content can depend on many variables, not least availability and consistency of recyclate supply.


Analytical approach and data used BRE has Environmental Profile data on 3.5 N and 7 N lightweight blocks from a study conducted in collaboration with the Concrete Block Association (CBA) in 2004. There are also a number of proprietary product datasets giving a total of 20 data sets that have been used. These inventories are commercially sensitive and have been supplied in confidence. Due to this sensitivity, the conclusions drawn are presented as trends and from a holistic perspective across LCA datasets.

The environmental impact – analysis and observations

The results for lightweight blocks suggest that the level of recycled content within lightweight blocks has no explicit correlation with kg CO2 eq.(100 years) performance (see figure 2.6.1). Drawing a trend line for all lightweight blocks demonstrates no tangible change in kg CO2 eq.(100 years) with increasing recycled content. Therefore, moving from standard to good practice recycled content in lightweight blocks provides no significant change in kg CO2 eq.(100 years) performance. On the other hand, on an Ecopoint basis a trend is evident where the greater the recycled content the lower the Ecopoint and therefore the better the environmental performance (see figure 2.6.2). On average, moving from standard to good practice provides a reduction in Ecopoints of approximately 0.3 Ecopoints/m2 of lightweight blocks in a wall. However, the best performing lightweight block at standard practice has fewer Ecopoints and, therefore, a lesser environmental impact than the worst performing lightweight block at good practice recycled content. This highlights that individual proprietary lightweight blocks have environmental footprints that are significantly different to the general trend line. The study produced for the CBA in 2004 demonstrated that mineral extraction was the most significant environmental impact associated with lightweight blocks, followed by climate change. The former of these is the principal reason why an improvement in Ecopoint performance is evident with increased recycled content. The latter of these is influenced predominantly by the energy used and resultant carbon emissions in cement production. From all the materials used within lightweight blocks, cement has a disproportionately high environmental impact. In BRE’s experience, the cement content of lightweight blocks varies between 4% and 11%. Although within dense blocks it has been demonstrated that higher levels of recycled material often require higher levels of cement to ensure that physical properties, such as strength, are maintained – which would tend to negate any improvement in overall environmental performance – data shows that in the case of lightweight blocks this rule does not apply. Therefore, there is no set explicit correlation between recycled content and the quantity of cement used.


Figure 2.6.1: Recycled content of lightweight concrete blocks vs kg CO2 eq. (100 years)

Lightweight block

6065707580859095

100105110

0 10 20 30 40 50 60 70 80 90

% recycled content

kg C

O2

eq p

er m

2

Use of recycle agg Use of

recycle agg&/or fly ash


No recycled content

Figure 2.6.2: Recycled content of lightweight concrete blocks vs Ecopoints

Lightweight blocks

0

0.5

1

1.5

2

2.5

3

0 10 20 30 40 50 60 70 80 90

% Recycled input

Eco

poin

ts p

er m

2

Use of recycle agg Use of

recycle agg&/or fly ash


No recycled content

Transport The environmental impacts associated with the typical transport of the lightweight concrete block products considered in this report were found to be insignificant compared to the overall environmental impacts. For this reason a more in-depth transport analysis has not been undertaken.


2.7 Roof tiles Table 2.7.1: Roof tiles recycled content levels

Existing Revised

% by mass

Application


Concrete tiles 0 10 0 5

Fibre cement tiles 0 5 - -

Reconstituted resin bonded slates 43 80 - -

Polymer-modified cement tiles 30 - -

Recycled content materials considered Aggregate resources Cementitious material For concrete tiles - Generic recycled aggregate

- PFA - GGBS

For fibre cement tiles - Waste slate

- PFA

For reconstituted resin bonded slates - Waste slate

- PFA

For polymer-modified cement tiles - Waste slate

Statement of findings Improvement in environmental performance, both in kg CO2 eq. (100 years) and Ecopoints can be achieved by moving from standard to good practice recycled content within the different roof tile types. However, environmental performance has been found to be manufacturer and plant specific as different manufacturing facilities have markedly different environmental performances even when the finished product is very similar. It is also possible to find standard practice tiles that perform better than good practice. Therefore, there is no universal rule that can be applied to roof tiles on the use of recycled impact and the resultant environmental impacts; improved environmental performance with higher recycled content constitutes the average trend. Product background There is a large array of different roof tiles available on the UK market and these can be broadly categorised on a material composition basis. Historically, clay and slate tiles have been the most accessible: however, artificial tiles, which offer the opportunity for using recycled content, have become increasingly commonplace. Artificial tiles can be separated into four main categories: concrete tiles, fibre cement tiles, reconstituted resin bonded slates and polymer-modified cement tiles. The number of material constituents within a roof tile is generally much greater than in the other “concrete” products considered in this report. As with these other products, there are some essential


base ingredients such as a binder and aggregate materials. However, a panoply of resins, paints, oils and pigments and other additives are also commonly added. Recycled content In BRE’s experience, recycled aggregates can be used to replace virgin aggregate but by far the most common replacement is slate waste. With the exception of the concrete tiles, all the other roof tile types considered use slate waste as the principal recycled material. With regard to cementitious material, GGBS and PFA can be used. Recent analysis of recycled content of building products by AMA Research Ltd suggests that 10% recycled content for concrete roof tiles may be an overestimation and that 5% may be closer to the correct figure. This has been reflected in the table above. Due to the lack of data sets for fibre cement tiles, reconstituted resin bonded slates and polymer-modified cement tiles, it is difficult to judge whether the published recycled content figures in Table 2.7.1 are current. By contrast, for concrete tiles where BRE has a larger number of data sets, the values are considered to be indicative of industry practice. Nevertheless, the encapsulated data have been collected over the last seven years and therefore current practice may differ. If we assume that they are representative of industry practice then there is a justification in suggesting that 10% recycled content at good practice is a slight overestimation. A large number of concrete tiles fall within 4% and 9% recycled content and only very few have around the 10% recycled content. Therefore, 6% or 7% might be a more appropriate figure for good practice recycled content in concrete tiles. Analytical approach and data used The analysis of roof tiles considers 24 data sets, of which 17 are concrete roof tiles, three are fibre cement, two are polymer modified and two are resin based. These are the result of collaborations between various industry partners in previous studies and are commercially sensitive. Therefore the results that are presented are done so in a general way portraying trends rather than individual performance results.

The environmental impact – analysis and observations

If one analyses all the roof tile categories together, but taking into account that there are many more data sets available for concrete tiles than the other categories, it is evident that the environmental impact is roughly comparable (see Figures 2.7.1 and 2.7.2), on the basis of both kg CO2 eq.(100 years) and Ecopoints, irrespective of the level of recycled content. It was felt that there are insufficient data sets to provide a fair comparison of standard and good practice recycled content for polymer-modified and resin-bonded tiles, therefore, concrete tiles and fibre cement tiles have been analysed in greater detail, whereas the former two have not. This is recognised as a data gap that ideally will be filled in future research of this kind.


Figure 2.7.1: Recycled content of roof tiles vs kg CO2 eq. (100 years)

Roof tiles

5

10

15

20

25

30

35

0 10 20 30 40 50 60 70

% recycled content

kg C

O2

eq p

er m

2

No recycled content

Concrete

Fibre cementResin

bonded

Polymer modified

Figure 2.7.2: Recycled content of roof tiles vs Ecopoints

Roof tiles

0

0.05

0.1

0.15

0.2

0.25

0.3

0 10 20 30 40 50 60 70 80

% Recycled input

Eco

poin

ts p

er m

2

Concrete

No recycled content

Fibre cement

Resin bonded Polymer

modified


Concrete roof tiles Drawing general trends from standard to good practice for concrete roof tiles shows no improvement in kg CO2 eq.(100 years) results, but some improvement in Ecopoints (see Figures 2.7.3 and 2.7.4). Importantly, the use of cement replacement (PFA and GGBS) does not automatically assume a lesser quantity of cement and in turn a kg CO2 eq.(100 years) saving is not a corollary of the inclusion of cement replacement material. Figures 2.7.3 and 2.7.4 portray a broad range in the kg CO2 eq.(100 years) results for the different concrete tiles between the published standard and good practice percentages (there are few data sets at higher recycled levels and therefore the range is reduced). The difference in kg CO2 eq.(100 years) results irrespective of recycled content is due to the differences in energy consumption that are apparent in different production facilities and in the production processes of the different additives that are used, of which there are many. The apparent reduction in Ecopoints with increased recycled content shown in Figure 2.7.4 is almost wholly down to the reduction in mineral extraction with the substitution of virgin aggregates with recycled aggregates. Although there is significant variation in the other environmental impact categories, compared to kg CO2 eq.(100 years) (climate change) and minerals extraction impacts they are very small, therefore the differences have a limited influence on the overall Ecopoint results. Figure 2.7.3: Recycled content of concrete roof tiles vs kg CO2 eq. (100 years)

Concrete roof tiles

5

10

15

20

25

30

0 5 10 15 20 25

% Recycled input

kg C

O2

equi

v pe

r m2

No recycled content



Figure 2.7.4: Recycled content of concrete roof tiles vs Ecopoints

Concrete roof tiles

0.1

0.12

0.14

0.16

0.18

0.2

0.22

0.24

0 5 10 15 20 25

% Recycled input

Eco

poin

ts p

er m

2

No recycled content


Fibre cement tiles Due to the reduced number of data sets for fibre cement tiles, it is difficult to draw conclusions with the same level of confidence as has been done with concrete tiles. However, it would appear that increasing the recycled content from standard to good practice does provide environmental benefits both in terms of kg CO2 eq.(100 years) and Ecopoints, although using the latter metric the improvement is more significant (see Figures 2.7.5 and 2.7.6). Nevertheless, due to the great variability in composition of the tiles (i.e. the material inputs for the tiles considered are very different) and the variations in their associated extraction, processing and production processes, one can suggest that the environmental improvements depicted are as much a symptom of these differences and not the minor increase in recycled content of 5%.


Figure 2.7.5: Recycled content of fibre cement roof tiles vs kg CO2 eq. (100 years)

Fibre cement roof tiles

15

17

19

21

23

25

27

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5

% Recycled input

kg C

O2

per m

2

No recycled content


Figure 2.7.6: Recycled content of fibre cement roof tiles vs Ecopoints

Fibre cement roof tiles

0.14

0.145

0.15

0.155

0.16

0.165

0.17

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5

% Recycled input

Eco

poin

ts p

er m

2

No recycled content


Transport The environmental impacts associated with the typical transport of the ceiling tile products considered in this report were found to be insignificant compared to the overall environmental impacts. For this reason, a more in-depth transport analysis has not been undertaken.


2.8 Clay facing bricks

Table 2.8.1: Clay facing bricks recycled content levels Existing Revised

% by mass Application

Standard Good Standard Good Clay facing bricks 0 10 - -

Recycled materials directly and indirectly considered Resources Minerals

- Calcium Carbonates - Colliery Spoil - Water Treatment Residues (WTR) - Pottery Waste - Silt Sands - Fireclay - Glass

Hydrocarbons

- Coal and Coke fines (Slurry or Breeze) Ash

- Incinerated Sewage Sludge Ash (ISSA) - Pulverised Fuel Ash (PFA) - Town Ash

Industrial minerals

- Foundry Sands - Slags - Rockwool - Refractory Grog

Organics

- Sawdust - Sugar/Starch

Statement of findings The constituent input materials including recycled content and process of manufacture are not consistent within the brick industry. This means the environmental impacts of each product type or group need to be examined in their own right. It has not been possible to review this because there are insufficient LCA data on the use of recycled materials in brick manufacture. The data limitations mean it is difficult to determine if the use of recycled material will result in environmental improvement. From a minerals extraction perspective, information does indicate that


there is potential for environmental benefit. The magnitude of this will potentially vary significantly between fire clay products that might be considered to have 100% replacement of clay with a recycled content to others which use smaller percentages of recycled content to achieve aesthetic appeal. Product background Brick is one of the most widely used construction products in the UK. With an established history dating back to the industrial revolution, the general approach to manufacture has changed little with time. By contrast, the technologies behind the brick production have advanced, and the industry continues to examine its efficiency in energy and resource terms. There is large variation within the market when considering product recycled content. This reflects the technical needs of the market, the legacy of manufacture location, and the chemical properties of different brick production processes. Recycled content Across the sector, standard practice recycled content for a product is considered as 0% and good practice as 10%. However, statistics shown in Table 2.9.1 demonstrate that the industry average across all products is significantly higher than 0%. The range of recycled materials used in the brick sector is also reviewed in this Table. Table 2.8.1. : Use of secondary and recycled materials in UK brick production

Material group Tonnage % of Virgin Raw Material

Minerals 526,000 6.92% Hydrocarbons 58,000 0.76% Ash 28,000 0.36% Industrial Minerals / By-Products

20,000 0.26%

Organics 2,500 0.03% Total 633,000 8.33%

Analytical approach and data used BRE has a detailed LCA dataset for UK generic brick production. This was developed in the period 1998-1999. At this time, recycled content was not reported within the Environmental Profiles methodology and therefore a historical picture of industry performance does not exist with respect to this issue. Notwithstanding this, the 1999 dataset provides a useful insight into the environmental impacts of brick production. Further, for the purposes of this study it has been possible to adjust the profile to provide an indication of the environmental implications of current recycling initiatives in the sector. This work has been supported by the Brick Development Association (BDA) and CERAM Research, both of whom have provided input into the project via information and discussion. In return for its support, the sector has asked for an honest presentation of facts and clear description of the technical challenges facing the industry. In this respect a formal request was made to ensure that the evidence presented in the report was not separated from discussion. This would avoid findings being taken out of context. The environmental impact – analysis and observations Brick products are in the main manufactured using virgin clay sources. They do however show variation in composition both in the type of raw material (clay), the other input materials and in the


processes used for their manufacture. This has significant effect upon technical viability of using non virgin clay materials. Despite this it is possible to observe large differences in products on the market, whereby in the main, the majority of products have no recycled content and others have up to 100% non virgin clay raw material. Within this context the environmental impacts of brick production can be attributed to two central issues. These are energy use and minerals demand. Both carry roughly equal environmental weighting when considering a generic brick production process on a per tonne basis. Collectively they equate to approximately 85% of the production impacts (cradle to factory gate) when assessed using the BRE Environmental Profiles methodology. Energy requirement causes environmental impact in the fields of climate change and fossil fuel depletion. By contrast, virgin clay extraction causes impacts in the minerals extraction impact category. For the industry to make meaningful environmental improvement, it will be necessary to look at virgin material replacement (so as to minimise extraction impacts) and make improvement to its energy demand (to reduce climate change emissions and reduce fossil fuel usage). Using recycled materials is an important contributor to government policy objectives which are looking to promote resource efficiency. Therefore at face value, there appears good synergy between using recycled material and improving the environmental impacts of brick production. However, this is subject to the assumption that recycled materials have a lower intrinsic embodied environmental impact than primary clay, and that they do not increase energy demands or other process requirements during brick production. There exist only limited data to substantiate these positions and industry steer to this work is not been able to confirm performance one way or the other. Research which provides some insights into the potential for energy saving in using recycled content materials is the WRAP work in report GLA2-018 “To demonstrate commercial viability of incorporating ground glass in bricks with reduced emissions and energy savings.” The results from the trial study with the sector showed a potential energy saving of equivalent to 20%. This was primarily due to reduced firing times (viz. a 7.7% time saving was achieved for the specific paver product, that had a firing period of 61 hours and which used 5% recycled glass, equal to a reduction of kiln time of almost five hours). A saving of 70°C was also achieved on the firing top temperature of 1150oC. These improvements were achieved in a intermittent kiln and results of tunnel kilns were less significant. The study concluded that for an intermittent kiln a modest reduction in firing time and temperature can result in a significant reduction in energy usage. It is clear that even savings of this small scale do result in environmental improvement. Unfortunately the energy consumption figures for this scenario have not been made available which makes it impossible to translate an 8% saving on firing time into an environmental metric such as carbon reduction. It is also not possible to translate the findings to other recycled content clay brick options because of expected technical performance changes in the product. In summary, although the findings provide illustration of the potential environmental gains for one specific type of product and process, they cannot be taken as evidence for manufacturing practice across the industry. Economic viability as with all product manufacture is critical to the business. Process costs for the brick sector are relatively high and make up the majority of product manufacture cost. These costs arise mainly from energy purchasing. By contrast, raw materials costs are low. The outcome is that recycled content will not be used if it results in increased energy cost, or if it has higher capital cost than primary clay. Industry states that “the majority of non virgin materials added to the clay body during the manufacturing process offer little, if any, significant reduction in energy usage”. Although this opinion is not backed up by data, conversely, there is no evidence to refute the claim either. In 2005 CERAM undertook a study to identify the range of recycled materials used by the sector and the relative proportions. Basing its conclusions on 2004 data from more than 90% of industry operators, it calculated that the sector was using approximately 8% recycled content as an average


across all products. These calculations require careful review, given the work being undertaken for WRAP by BRE to develop and agree ”Rules of Thumb” for declaring the recycled content of products. Notwithstanding this, if this quoted industry figure were taken, it would indicate that approximately 8.3% of primary virgin raw material is being replaced with recycled alternatives. Ignoring the inherent value of these materials and assuming they carry with them no commercial value+ (which is perhaps not a fair position to take,) this equates to an 8.3% reduction of the minerals extraction impacts of the industry. On a per tonne level for generic brick, the minerals extraction impact is equivalent to 40% of the impact of the product. The figure of 8.3% therefore equates to a 3.2% overall reduction in environmental impact of the product at the per tonne level. These rudimentary calculations really require a more robust set of numbers behind them. Specifically, the value of recycled content material is important because it is used as a surrogate for allocating forward the environmental impacts from a previous life cycle stage into the next. More detailed assessments within the specific product categories are also required. Specifically, the implications of both primary clay and recycled content to the production process and its energy demand are critical. They influence kilning period and temperature and as such environmental impact. The trends across different brick products, their constituent input materials and process of manufacture are not consistent. Therefore, the environmental impacts of each product category need to be examined in the own right. There are insufficient data as yet to complete this. Transport Brick can be classed as a high mass building product and therefore it is probable that the transport of bricks may have a significant impact on the environmental performance of the delivered product. However, contrasted against this is the fact that production is responsible for high minerals and energy use. Therefore the magnitude of transport impacts is significantly less in proportion to manufacture than for many building materials. Additionally, the delivering distances could be crucial to the performance. Strict distances for typical brick deliveries to site have not been possible to obtain, however dialogue with brick manufacturers and the major building merchants should be able to produce some figures with a sufficient degree of confidence. The Department of Transport’s Road Freight Statistics 2005 state that the average building material travels 122 miles (195km) to site from its last point of sale. Compared to the transport of certain bulk materials, such as aggregate and ready mix concrete which are known to travel shorter distances, this is a significant distance and, therefore, may be significant in relation to the overall environmental performance. This area is recognised as a gap and requires greater research and enquiry.

+ The value of recycled material is important to the Environmental Profiles LCA because it is used as the basis for

determining the magnitude of environmental impact that is carried forward from a previous life. This is calculated based on the relative difference between the value of the recycled material as a primary resource and its value as a secondary post-consumer resource. These value differences are used as a proxy for determining the embodied environmental burden of the material at post consumer recycling.


2.9 Plasterboard Table 2.9.1: Recycled content levels

Existing Revised

% by mass

Application


Plasterboard 36 84 36 84

Recycled content materials considered Gypsum Covering Natural gypsum Paper Desulphogypsum Titano gypsum

Statement of findings Due to a lack of detailed LCA data, BRE have been unable to provide any guidance on the possible benefits of using recycled plasterboard or synthetic gypsums within plasterboard. BRE recommend that more detailed LCA work is required to ascertain the potential benefits of using recycled plasterboard and synthetic gypsums within plasterboard. The choice of methodology used in this work to allocate environmental impacts to by-products and recycled products will be a key factor in this work. WRAP has recently commissioned a detailed assessment of the environmental impacts of each stage in the product life-cycle of plasterboard, including waste and recycling. Product background The vast majority of plasterboard sold in the UK is manufactured within UK borders and by three companies. However, the main component of plasterboard, gypsum, can be sourced from within the UK or a number of other European countries – most notably, Germany, Italy, France and Spain. Plasterboard is made by pressing and drying gypsum slurry between facing sheets of paper, or paper and foil. The gypsum itself can either be sourced from naturally occurring deposits, pre-consumer recycled plasterboard waste and synthetic gypsum, arising as a by-product from other processes – such as flue gas desulphurisation (FGD) within the electricity industry (FGD gypsum or desulphogypsum), and the treatment of by-products such as sulphuric acid for example from titanium dioxide manufacture (“titanogypsum”). Synthetic gypsum is also produced from citric acid productionxvi (“citrogypsum”) and the manufacture of hydrofluoric acid (“fluorogypsum”), although we are not aware of these synthetic gypsums being used within the UK for plasterboard. FGD gypsum represents the largest volume of synthetic gypsum used in plasterboard. Recycled gypsum Post-consumer plasterboard is not generally considered for recycling into plasterboard due to issues of contamination, and although research has recently been undertaken in the UK and the Netherlands into this type of recyclingxvii and volumes are increasing, plasterboard recycling is still predominantly pre-consumer. Post-consumer plasterboard is commonly used as an input within cement manufacture.


For pre-consumer recycled plasterboard (plasterboard arising from new-construction and returned from site to the factory), there are a number of recyclers serving the plasterboard industry. The levels of recycling are currently limited, but the industry has capacity to increase production if the supply logistics can be improved. Contractors generally pay more for plasterboard if a take back scheme is in operation, but will avoid landfill costs as a consequence. The paper from the plasterboard must be removed as the paper content of the recycled plasterboard limits the amount which can be used due to the effect on manufacturing process. The paper is then disposed of, for example through composting. Knauf Drywall claim that the removal of paper from plasterboard offcuts also requires greater energy than using raw gypsumxviii. BRE have checked this statement with Knauf and there appears to be no direct evidence to support this statement – there are energy costs associated with extracting, transporting and processing natural gypsum, synthetic gypsum and waste plasterboard but further work would be needed to provide a full energy balance/LCA for each route. Synthetic gypsum The shared purpose of the production of synthetic gypsum in the different industry sectors in which it is found is to remove the detrimental environmental impacts of waste products from those industries (such as sulphur from power station emissions). However, it was soon realised that its production had an added benefit of providing a ready and usable material for gypsum products. Currently, the synthetic gypsum market for flue gas desulphurisation gypsum is well established and all of the FGD gypsum produced in the UK is used, indeed significant volumes are now imported from Europe. Synthetic gypsum has a generally higher purity than naturally occurring gypsum (96% compared to 80% typically, though some high purity gypsum is mined in the UKxix). The Environmental Profiles methodology attributes environmental impacts to these by-products on the basis of their relative value to the main product. As many of the processes producing gypsum by-products have high impacts, this may result in high impact for the by-product, even though it has low value. BRE have been unable to obtain reliable data from the plasterboard industry at this stage to determine what impact the use of synthetic gypsum has on the overall process. FGD gypsum Whereas natural gypsum is normally sourced as stone and ground into powder as part of the plasterboard manufacturing process, FGD gypsum is normally supplied in granulated form and therefore requires less processing by the plasterboard manufacturer, though it generally has a higher moisture content and therefore requires greater drying. FGD gypsum is a by-product of the coal fired electricity industry and is produced when SO2 is scrubbed out of the exhaust gases sent up the cooling stacks using crushed limestone in a slurry. This process requires the extraction and use of crushed limestone, water and energy, and results in a process emission of CO2. Titanogypsum This is a by-product of the titanium dioxide pigment industry using the sulphate process, and is produced to reduce the amount of sulphuric acid which is emitted to water by the industry. As with FGD gypsum, limestone and water are used to react with the sulphuric acid to produce calcium sulphate. For example, sulphuric acid is currently emitted to water from the Huntsmans TiO plant in Grimsby at the rate of 620 kg/ tonne of TiO producedxx. The impact assessment methods used by BRE do not provide any indication that release of sulphuric acid to water will cause any environmental problems, however the Australian Government’s NPI system rates sulphuric acid with a score of environmental hazard rating of 1.3, where 0 is no impact and 3 is extremely hazardous.xxi The emission is regulated by the Environment Agency but the Huntsman factory is within its limit of 800 kg/tonne TiO.


Material sources for paper facings The paper facing of plasterboard is normally based on recycled paper pulp and accounts for about 4% of the mass of plasterboard. The relative importance of using recycled paper pulp is minimal compared to the impact of the much greater percentage of gypsum and its greater environmental impact. Recycled content Calculation of recycled content for plasterboard has been complicated by the fact that synthetic gypsum may not be considered as a waste. For example, the Environment Agency has just ruled that FGD gypsum is not a wastexxii. This is because, historically, all FGD gypsum has been utilised by the plasterboard industry and none goes to landfill. Work for WRAP by BRE on defining “Rules of Thumb” for declaring the recycled content of construction products was in progress at the time of writing this environmental assessment report. Near the completion of this report, the Commission of European Communities published an Interpretative Communication on waste and by-products.xxiii The Communication clarifies how to distinguish ‘non-waste by-products’ which might be regarded as recycled content. In particular, the Communication recognises that FGD gypsum, while not a ‘product’, is a production residue and can be classed as a ‘non-waste by-product’. In the case of FGD gypsum, this enables the product of the scrubbing process, i.e. calcium sulphite, to be regarded as recycled content. This includes the calcium carbonate that is mixed with the sulphur dioxide ‘waste’ emissions in the scrubbing process to produce the calcium sulphite. If this approach is taken, then the potential maximum recycled content levels of FGD gypsum plasterboard will be significantly greater than if the SO2 is regarded as the recycled content alone. Bearing this in mind, the report retains previously reported values of 36% and 84% recycled content for standard and good practice respectively. Analytical approach and data used Due to an absence of data, no detailed analysis has been undertaken.

The environmental impact – analysis and observations Providing information on the environmental impacts associated with using natural gypsum, recycled plasterboard or synthetic gypsum has not been possible due to a lack of data. The impacts of natural gypsum extraction vary depending on whether the gypsum is from deep mines or open cast. Additionally it will vary depending on the richness of the ore, the proportion of gypsum to anhydrite, and whether the anhydrite is also sold or returned to the mine. Some gypsum is mined in the UK, other gypsum is sourced from Europe with additional transport. A further problem in reviewing available datasets is ascertaining whether grinding and milling are included or excluded from the profile or the plasterboard process. BRE have found figures ranging from 0.03 to 2 MJ/kg and 2-250 g CO2/kg but more work is needed to map data to the actual UK situation. BRE have been unable to obtain any data regarding the transport, processing or use of pre- or post-consumer recycled plasterboard and so are unable to provide any guidance regarding the benefits of using recycled plasterboard at this point. The Environmental Profiles methodology attributes environmental impact to by-products on the basis of their relative value – for example, BRE estimates that FGD gypsum has 0.8% of the impact of coal-fired electricity as BRE understands the electricity industry sell FGD gypsum and that the industry generates 0.8% of their income from selling FGD gypsum. This gives FGD gypsum an impact of approx 3.8 MJ/kg and 290 g CO2/kg. This is based on information provided confidentially to BRE for one plant, together with publicly available data on coal fired electricity production and would require


checking with the electricity industry. BRE do not have access to value data for the titanogypsum manufacturing process. Many other alternative methods of allocating environmental impact to by-products could be used, such as to allocate all the impact to the main product (in this case electricity or titanium dioxide) and none to the synthetic gypsum; to allocate by mass (where both products have mass); to allocate the impacts of production of calcium sulphite to electricity, and oxidation and product drying to synthetic gypsum; or to attribute only the impacts of the FGD/titanogypsum process (use of limestone, water, energy and process CO2 emissions) to the synthetic gypsum. BRE do not have sufficient information at present on the FGD or titanogypsum process to undertake an assessment of this final method, although at a minimum, this would result in an emission of 282 g CO2/kg, based on stoichiometry. Additionally, BRE do not have detailed data on the individual processes within the plasterboard manufacturing process to ascertain the differences between process energy and impacts for the various inputs to the processes, such as drying or paper separation for example, which will vary for the different inputs depending on moisture content. Transport The environmental impacts associated with the typical transport of the plasterboard products in the UK are insignificant compared to the overall environmental impacts. For this reason, a more in-depth transport analysis has not been undertaken.


2.10 Chipboard

2.10.1 Recycled content levels Existing Revised

% by mass

Application


Chipboard (chipboard) 65 70 - -

Recycled content materials considered Wood chips Logs from forests or sawmill rejects Chips and sawdust (mainly from sawmills) Post-consumer timber, such as packaging (particularly pallets)

Statement of findings Moving from standard practice recycled content of 65% to good practice of 70% is unlikely to cause much change in the environmental impact of the product. This conclusion is based on the likelihood that the increased amount of recycled timber will come from post-consumer sources where the CO2 sequestered in the recycled timber will probably offset any impacts associated with the transport and cleaning of the material; post-consumer sources can also avoid the impacts associated with using virgin timber, which, in the UK, are dominated by fossil fuel use and infrastructure needs. Transport impacts associated with moving from standard to good practice recycled content will depend on the logistics adopted for both the material inputs to the process and for distributing the chipboard. It is unlikely that moving from standard to good practice will affect the amount of timber going to landfill since the chipboard and wood panelboard sector as a whole is already in competition with the energy production sector for much of its recycled timber materials. Product background Manufacture Chipboard is made using wood chips and a thermosetting adhesive using either a continuous press or a multi-daylight press. The panel is structured to have three layers with smaller, closer packing particles on the outer layers and larger, more open packing particles in the core. Adhesive is added at a rate of around 8% of the dry weight of the wood chips. The adhesives used are:

formaldehyde-based: o urea (UF) o melamine (MF), o melamine and urea (MF/UF or MUF) o phenol (PF), or o melamine, urea and phenol (MUPF)

isocyanate (polymethyldiisocyanate, PMDI)


PMDI can be used alone (for example, in zero formaldehyde boards) or in the core of a board with a formaldehyde-based adhesive in the outer layers. Panels have a moisture content of around 5-8% (dry mass basis) when produced. Material sources for wood chips Wood chips can come from a variety of sources:

roundwood logs from forests or sawmill rejects; sawmill co-products of chips and dust; reclaimed, post-consumer timber, such as packaging (including pallets) or demolition wood;

and/or panel production rejects or off-cuts.

Implications of material source A key determiner of chipboard properties is the geometry of the wood chip; the geometry needs to be carefully engineered to ensure that the chipboard achieves the desired standard performance. The required geometry is most readily achieved using roundwood or sawmill chips. Pallets and other sources of solid timber with relatively large and standardised dimensions can also be processed to achieve the required geometry. However, the use of reject panels and off-cuts is usually less than 5%xxiv because the desired chip geometry is difficult to achieve, the level of fines and small particles increases and more resin is needed to achieve standard performance in the final panel. Increased resin content increases costs and the increase in fines and small particles also increases density, which can adversely affect processing and panel performance. As pointed out by Hamilton et al. (1995)xxv, reclaimed, post-consumer timber presents several issues that must be addressed to ensure its successful use as a raw material substitution for chipboard production. These issues include:

type of material; quality of material, particularly:

o contamination with other materials such as oil, dirt, stones, thermoplastics and non-magnetic metals

o treatment with fire retardants and preservatives o moisture content;

continuity of supply and storage needs; and location of material and transport needs.

Nevertheless, chipboard commonly includes a large fraction of recycled timber. Recycled content Calculation of recycled content for chipboard is complicated by the fact that the board contains moisture due to the physical properties of the chips. The mass of the final panel will be the combined masses of the wood chips (made denser than the original wood because of pressing), resin and moisture. A UF-bonded chipboard has a density of around 635 kg m-3 at 8% moisture content. One kg of UF chipboard contains around 0.96 kg chips and roughly 0.04 kg of resin (the minor inputs of wax emulsion and fire retardants etc. have been ignored here), giving a maximum recycled content of 96%. Chipboard recycled contents are typically calculated on the basis of weighbridge figures and the industry average is usually quoted as 65 – 67%, with a maximum of 95%xxvi. WRAPxxvii states that


chipboard has a recycled content by mass of 65% as standard, 70% as good and 90% as best practice. The environmental impact – analysis and observations The Environmental Profiles methodology (Howard et al., 1999)xxviii excludes the impacts of the previous life from the environmental profile of post-consumer reclaimed or recycled materials that have no value; the only impacts taken forward into the new product are those associated with the transport of the material to the processing plant. For post-consumer reclaimed or recycled timber, this means that the impacts associated with forestry, primary processing and use of the timber in its original application are not carried forward into its new life. The transport logistics adopted are therefore key in calculating the environmental impact brought with the timber. Panel mills appear to have taken this on board and the vehicles used to distribute their product to local builders’ merchants are often used to collect reclaimed timber to be taken back to the mill.

In BRE’s LCA method, the carbon dioxide (CO2) sequestered in the creation of the timber is carried forward into the new life; calculated according to dry matter content. The sequestered CO2 acts as an off-set to climate change impacts caused by further processing, transport and disposal and is, therefore, an environmental benefit to any product using virgin or reclaimed timber. The benefit is enhanced by the high weighting factor placed on climate change in the calculation of Ecopoints. Some environmental profiling methods require that the sequestered CO2 remains with the original life, however, the impacts associated with the breakdown of the carbon in the timber are still included in the impact of the product. Discussions with Wood Panel Industries Federation (WPIF) indicate that increasing recycled content (excluding reprocessed panel or reclaimed panel) does not necessarily lead to increased inputs of materials such as resins or energy or increased reject board: the energy needed to dry the chips depends on their initial moisture content; pallet timber will already have been dried and the chips from them are likely to require less drying than chips from logs; the moisture content of sawmilling chips and sawdust will depend on the time of year and whether the chips have been exposed to the weather. The WPIF also stated that increasing recycled content can increase the abrasiveness of the panel, which has implications for wear and tear on processing equipment and requires attention to the design of the equipment to minimise this effect. Using reclaimed timber does require more cleaning and quality control of the material, which requires the use of specialised machinery and generates waste. However, this machinery will process a lot of material in its lifetime and its contribution to each unit of panel production is likely to be small. Cleaning will produce more material requiring disposal, some of which will require specialist disposal with implications for environmental impact. A particular requirement is avoiding the inclusion of any treated timber; this leads to a precautionary approach so that if it is uncertain whether timber has been treated, it is regarded as treated and not used. Where the waste is regarded as hazardous under the Hazardous Waste Regulationsxxix, then its disposal options are limited to hazardous waste landfill site or incinerators that are able to accept this type of waste. Transport The transport impacts associated with moving from standard to good practice levels of recycling are difficult to assess because the impacts will depend on the transport logistics adopted by panel mills both for receiving their input materials and for distributing their chipboard. Panel mills appear to have considered this and often use the vehicles that distribute their product to local builders’ merchants to then collect recycled timber for delivery to the mill.


2.11 Thermal insulation Table 2.11.1: Recycled content levels

Existing Revised

% by mass

Application


Glass wool 30 50 - -

Cellulose fibre 80 85 - -

Expanded polystyrene (EPS) 0 25 - -

Mineral wool 50 50 25 50

Recycled content materials considered Application Recycled material Glass wool No data sets available for recycled content Cellulose fibre Scrap newspaper Expanded polystyrene (EPS) Post consumer recycled EPS Mineral wool Wet granulated blast furnace slag

Statement of findings

On a kg CO2 eq.(100 years) basis, all the insulation types perform comparably with the exception of cellulose insulation (see Figure 2.11.1). Cellulose insulation made from recycled newspaper has a negative kg CO2 eq.(100 years) result due to the sequestration of CO2 that occurs with the growth of the trees used for the newspaper pulp. However, if we were to consider the full life cycle of the cellulose insulation (from cradle to grave instead of cradle to gate) then the release of CO2 at its final disposal cancels out the previously achieved CO2 sequestration benefit. The result is that recycled cellulose insulation would have parity with mineral wool with recycled content between 25% and 40% recycled content. On an Ecopoint basis, all the insulation types perform comparably including cellulose insulation (see Figure 2.11.2). Moving from standard to good practice recycled content in EPS insulation sees improvement in both kg CO2 eq.(100 years) and Ecopoints results. BRE have access to too few data sets for glass wool, cellulose fibre insulation and mineral wool insulation to draw definitive conclusions related to the environmental impacts of specifying good practice instead of standard practice recycled content.


Figure 2.11.1: Recycled content of insulation vs kg CO2 eq. (100 years)

Insulation

-6

-4

-2

0

2

4

6

8

10

12

0 10 20 30 40 50 60 70 80 90

% Recycled input

Kg

CO

2 eq

uiva

lent

per

m2

Recycled EPS

No recycled content

EPS

No recycled content

glass wool

Mineral wool

Cellulose

Figure 2.11.2: Recycled content of insulation vs Ecopoints

Insulation

0

0.02

0.04

0.06

0.08

0.1

0.12

0 10 20 30 40 50 60 70 80 90

% Recycled input

Eco

poin

ts p

er m

2

Recycled EPS

No recycled content

EPS

No recycled content

glass wool

Mineral wool

Cellulose

Product background The different types of thermal insulation available in the UK vary greatly in terms of their composition, physical nature and most importantly their production process. The other important difference is the thickness that is needed to achieve the required insulation level. This latter point is taken into account by BRE’s approach by using the functional unit of the insulation (m2 of wall achieving Building Regulation thermal performance).

Note: Carbon sequestration would be negated at end of life


Recycled content The greatest concentration of EPS insulation data held by BRE have 0% recycled content and this concurs with WRAP’s stated standard practice recycled content for EPS insulation at 0%. However, good practice may be conservative on the basis of BRE’s data sets alone. There are no data sets at the stated 25% good practice level but there are a small number at 35% recycled content. The recycled contents of the other insulation types published by WRAP appear to be roughly correct. There remains confidence in the published levels of recycled content for the other types of insulation with the exception of mineral wool, for which recent research by AMA Research Ltd suggests that standard practice is closer to 25% recycled content than the previously published 50%. This has been reflected in the table above. Analytical approach and data used The analysis considers 25 actual data sets drawn from collaboration with the insulation industry, of which 19 are EPS insulation, 3 are cellulose, 2 are mineral wool and 1 is glass wool. It is clear that the greater the number of data sets used the greater the applicability the findings will have to the insulation type under scrutiny. Therefore, the findings for EPS insulation are going to be more representative than for the other three insulation types.

The environmental impact – analysis and observations It is possible to suggest that, on a kg CO2 eq.(100 years) basis, the greater the level of recycled content in thermal insulation, as a whole the better the environmental result (see Figure 2.11.1). However, thermal insulations with no recycled content vary significantly in their kg CO2 eq.(100 years) and can perform equally as well as insulations with much greater levels of recycled content. Cellulose insulation is the only thermal insulation type that performs significantly better than the best performing thermal insulation with no recycled content in BRE´s database. However, this is due to the fact that cellulose insulation has a negative kg CO2 eq.(100 years) result due to the carbon sequestration that takes place with the growth of the trees that would have provided the source for the paper pulp for the newspapers. If the sequestration benefit is subtracted from the final result, the recycled cellulose insulation has a similar carbon emissions result as mineral wool with between 25% and 40% recycled content. The results on an Ecopoint basis are very similar with the exception of the highest recycled content insulation, cellulose insulation, performing less well than on a kg CO2 eq.(100 years) basis (see Figure 2.11.2). The Ecopoint scores for cellulose insulation are roughly comparable with the EPS insulations with higher recycled content levels, glass wool insulations with no recycled content and the mineral wool insulations with recycled content between 25% and 40%.

EPS Insulation The majority of available data sets for EPS have between 0% and 5% recycled content. BRE have no data sets for a “good practice” product but have a small number at around 35% recycled content. Drawing a trend line for all kg CO2 eq.(100 years) results shows an improvement in performance with greater recycled content (see Figure 2.11.3). However, the best performing EPS insulations perform nearly as well as the insulations with around 35% recycled content. This appears to be a consequence of differing impacts between production plants used in each manufacture system. The greatest environmental impact associated with EPS insulation production is climate change (kg CO2 eq.(100 years)) due to the natural gas and electricity consumption used in production of the polystyrene beads that are used as the feedstock and production of the final insulation product. The overriding significance of the kg CO2 eq.(100 years) means that the Ecopoint results for EPS insulation are very similar (see Figure 2.11.4).


Figure 2.11.3: Recycled content of EPS insulation vs kg CO2 eq. (100 years)

EPS Insulation

4

5

6

7

8

9

10

11

0 5 10 15 20 25 30 35 40

% Recycled input

Kg

CO

2 eq

uiva

lent

per

m2


Recycled EPS

No recycled content

EPS

Recycled EPS

Figure 2.11.6 : Recycled content of EPS insulation vs Ecopoints

EPS Insulation

0.04

0.05

0.06

0.07

0.08

0.09

0.1

0.11

0 5 10 15 20 25 30 35 40

% Recycled input

Eco

poin

ts p

er m

2


Recycled EPSRecycled EPS

Transport As no conclusions can be drawn on moving from standard to good practice for mineral wool insulation, glass wool insulation and cellulose insulation, then the associated transport impacts cannot be fairly addressed. For EPS insulation, the impacts associated with transport of polystyrene beads


(both from virgin production and from post consumer EPS) and the transport of the finished EPS product content are so small that the transport distances that are travelled by these materials (even across national borders) in actuality are not nearly great enough to affect the environmental performance of the good practice recycled content product compared to the standard practice recycled content product.


2.12 Ceiling tiles Table 2.12.1: Recycled content levels

Existing Revised

% by mass

Application


Mineral ceiling tiles 10 50 >10 <50

Gypsum ceiling tiles 36 84 - -

Virgin materials Filler material Fibrous material Mineral ceiling tiles - Recycled paper - Perlite

Virgin glass fibre

Gypsum ceiling tiles - Natural gypsum

Virgin glass fibre

Recycled content materials considered Filler material Fibrous material Mineral ceiling tiles - Recycled paper

Recycled rock wool Recycled glass wool

Other recycled content materials Filler material Fibrous material Mineral ceiling tiles

Recycled slag wool

Gypsum ceiling tiles - Synthetic gypsum from various sources (see section on plasterboard)

Recycled glass wool

Statement of findings This section considers mineral ceiling tiles only. Gypsum ceiling tiles have not been analysed due to the difficulty in ascertaining the provenance of the gypsum used and if it is synthetic or virgin gypsum. Also whether synthetic gypsum can be classed as recycled content is in itself an ongoing debate that further confounds any analysis of recycled content of gypsum products (see section on plasterboard for further details). WRAP area currently conducting a dialogue with the plasterboard industry and other industry sectors to produce a set of guidelines for the calculation of recycled content in construction materials that takes into account the peculiarities of the different sectors. The objective is to produce a fair and objective set of recycled content figures for the materials in question. Moving from standard practice (10%) to good practice (50%) in mineral ceiling tiles appears to improve the environmental performance per m2 of ceiling tile produced (the chosen functional unit) in terms of kg CO2 eq. (100 years) (see Figure 2.12.1). However, mineral ceiling tiles when analysed on an Ecopoint basis per m2, show rising environmental impacts as the recycled content is increased to the higher practice recycled content level (see Figure 2.12.2). But it must be noted that these results are


founded on a small number of proprietary data sets outside of the standard and good practice recycled content levels, which have been extrapolated to give an indication of the likely results for tiles at the recycled content levels relevant to this study. This has been possible as industry confirm that the production process is unlikely to change with changes in recycled content. Figure 2.12.1: Recycled content of mineral ceiling tiles versus kg CO2 eq. (100 years)

Mineral ceiling tiles

0

1

2

3

4

5

6

7

0 10 20 30 40 50 60 70

% Recycled Content

kg C

O2

eq. p

er m

2


No recycled content

Use of recycle mineral wool: rock wool or glass wool

Figure 2.12.2: Recycled content of mineral ceiling tiles versus Ecopoints per m2

Mineral ceiling tiles

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0 10 20 30 40 50 60 70

% Recycled Content

Ecop

oint

s pe

r m2

Standard practice

No recycled content

Good practice

Use of recycle mineral wool: rock wool or glass wool


Product background Mineral ceiling tiles are most commonly used in the UK in office and retail buildings. They are almost always used with a suspended ceiling system that is usually made from lightweight aluminium. The suspension systems are not considered in this report and the environmental impacts of ceiling tiles alone are analysed. Mineral ceiling tiles are primarily composed of a fibrous material (fibres made from stone, glass or slag), a filler material, often perlite, and a binder material. In BRE’s experience, perlite is the material used for the filler and cannot be easily replaced by alternatives. Perlite is a naturally occurring siliceous rock and it has a distinguishing feature from other volcanic glasses that when heated to a suitable point in its softening range, it expands to between four to twenty times its original volume. This expansion is due to the presence of two to six percent combined water in the crude perlite rock. When quickly heated to above 1600°F (871°C), the crude rock pops in a manner similar to popcorn as the combined water vaporizes and creates countless tiny bubbles, which account for its lightweight property. In addition to providing thermal insulation, perlite enhances fire ratings, reduces noise transmission and is rot, vermin and termite resistant.xxx Industry dialogue suggests that a correlation exists between siliceous rock and the fire rating of the ceiling tile with the greater the quantity of siliceous rock the better the fire rating. However, other materials are needed to provide acoustic properties. Waste paper is often used for acoustic performance but this has obvious fire implications. Therefore, a compromise threshold percentage content for the fire-resistant lightweight filler material (predominantly perlite) and the acoustic filler material (predominantly paper or starch) seems to exist wherein alterations greater than a few percent begin to affect the acoustic performance and fire rating performance. Ball clay is also used as a secondary filler in mineral ceiling tiles, providing plasticity in the production process to prevent cracking. Fibrous material - Mineral wool Mineral wool is made from molten glass, stone or slag that is spun into a fibre-like structure which provides the strength to the ceiling tile. The resultant products are known as glass wool fibres, stone wool fibres and slag wool fibres respectively. Glass wool is made from sand or recycled glass, limestone and soda ash; these are the same ingredients used for familiar glass objects such as window panes or glass bottles. In addition, glass fibre has boron added to improve its moisture tolerance.xxxi The glass wool waste used in mineral ceiling tiles can come from waste from the insulation industry (available in fibrous baled form, ready to be mixed in the ceiling tile manufacture process) or recycled bottles from the drinks industry (available as bottles which need to be crushed, melted and spun into fibrous form). Dialogue with the industry suggests that the latter source requires further processing than the former waste. Glass wool is used in higher percentages than the other two mineral fibre options. Stone wool is made from volcanic rock, typically basalt and dolomite, and when used typically only accounts for around 2% of the finished ceiling tile. Slag wool is made from blast furnace slag, a waste from the iron industry, and is a major ingredient in some mineral ceiling tiles. In ceiling tiles with higher glass wool content, glass fibres may be visible and therefore more paint may need to be applied to hide the fibrous look. Otherwise there appears to be no significant difference in the appearance of ceiling tiles with higher recycled content.


Binder material Different binder materials are used within the mineral ceiling tile industry varying from starch to resinous binders (AMA report for WRAP, 2006). Recycled content BRE’s findings suggest that mineral ceiling tiles manufactured and sold in the UK contain at least 10% recycled content. However, the majority of ceiling tiles with recycled content are found to have a recycled content of around 30%. Therefore, the recycled content at standard practice of 10% might be conservative. However, more dialogue with a broader representation of the mineral ceiling tile industry would be needed to support this supposition. The published recycled content at good practice of 50% also might require revision, but downwards rather than upwards. There are mineral ceiling tile manufacturers that produce both inside and outside the UK and some of their foreign produced tiles have up to 70% recycled content in ceiling tiles. They serve a relatively small percentage of the UK market for ceiling tiles, so may have influenced the published level of good practice unduly. Therefore, good practice at 50% might be an overestimation in the UK market and the figure might also need to converge closer to the 30% mark where most mineral ceiling tiles are found. Analytical approach and data used BRE’s proprietary data sets supported by ceiling tile manufacturers who supply the majority of the UK market for mineral ceiling tiles, were used to produce environmental impact results for mineral ceiling tiles. Across the raft of tiles considered, it was evident that the properties of acoustic, thermal, fire resistance correlate to the basic composition of the ceiling tile and, therefore, the materials used are dictated by market requirement for these properties. This study has identified data gaps on recycled slag wool. Hence the modelling and analysis of mineral ceiling tile datasets presented here excludes mineral ceiling tiles which contain slag wool. The environmental impact – analysis and observations The results for mineral ceiling tiles suggest that as the percentage of recycled content increases, the kg CO2 eq. (100 years) environmental impact stays the same (see Figure 2.12.3) whereas the Ecopoint environmental impact increases (see Figure 2.12.4). However, the available data sets provide minimal data for standard practice and only data up to 32% recycled content, which is 18% short of the published 50% for good practice. Secondly the range of environmental performance for the data sets around 30% recycled content is significant so that the data sets at 10% recycled content perform as well or better than some of the data sets at the higher recycled content level. Due to the limits of data and recycled content variability of the mineral ceiling tiles addressed, it is not surprising that there are no clear-cut reasons for the trends that have been produced. Addressing the materials individually does not provide easy answers either. The use of recycled paper has a small influence compared to the other materials used and, therefore, cannot be attributed with the change. The other main recycled component, glass wool, has significant climate change (kg CO2 eq.(100 years)) impacts and fossil fuel depletion impacts. Replacing virgin glass wool with recycled glass wool reduces these impacts due to the value allocation of impacts to by-products that is used within the Environmental Profiles methodology. Waste glass wool requires no further processing after production of glass wool apart from the addition of water to prevent it drying out. Some of the environmental impacts associated with the glass wool production are allocated to the waste according to its value compared to the primary product. Due to the wastes’ lower value the environmental impacts are lower. However, the use of recycled glass wool varies significantly between the different data sets available.


Recycled starch has a negative kg CO2 eq.(100 years) due to the carbon sequestration that takes place with the growth of starch-providing crops. On the other hand, the fertilizers used for cultivation of crops that provide starch, such as maize, result in significantly higher environmental impacts in human toxicity (water) and eutrophication. Due to the lack of data and obvious reasons for the change in environmental performance with a change in recycled content, one cannot make robust conclusions on moving from standard to good practice recycled content in ceiling tiles. The differences in production efficiencies and the variability of material composition in the ceiling tiles are not influenced enough by the recycled content for an increase in recycled content to provide a clear benefit or disbenefit in environmental performance. Transport The transport impacts of ceiling tiles were found to be insignificant relative to the overall impacts associated with the production of ceiling tiles, and therefore a more in-depth transport analysis has not been undertaken.


2.13 Floor coverings Table 2.13.1: Recycled content levels

Existing Revised

% by mass

Application


Generic carpet tiles 0 50 - -

Recycled content materials considered Bitumen Scrap polymer Scrap carpet Recycled PVC

Statement of findings There is an appreciable general trend of improving environmental performance with greater recycled content in carpet tiles in both kg CO2 eq. (100 years) and Ecopoint terms. However, there are many carpet tiles with moderate levels of recycled content, especially those with waste bitumen content, that perform equally well if not better than many carpet tiles with higher recycled content. Product background Carpet tiles are most commonly found in office and commercial buildings and are often used in favour of rolled carpets. They are composed of a backing material usually made from bitumen, PVC, latex or rubber, and the woven carpet fibre cover itself. Unlike domestic carpets, tiled products are not laid on an underlay, as a commercial floor (often smooth screeded) is not affected by the irregularity in level and draughts that affect traditional domestic wooden floors. They also have the advantage over rolled carpets of reducing waste off-cuts and allowing for damage and stained sections of carpet to be replaced without the need to remove entire rolls. Recycled content BRE believe the published figures for standard and good practice recycled content (see Table above) are representative of the carpet tile market. However, it is noticeable that most of the carpet tiles that BRE have had direct experience of around the good practice level use recycled PVC. This is indicative of how currently the percentage recycled content achieved is influenced by the recycled material that is used. When using bitumen (assumed here as a waste material), the recycled content sits between 10% and 30%. There are examples of carpet tiles in the UK market that achieve 90% recycled content by using recycled PVC up to 70% and scrap carpet up to 20%. Analytical approach and data used BRE have had significant experience with the carpet tile industry and has been able to consider 14 data sets, which are split between no recycled content PVC tiles, to tiles using scrap carpet, tiles using bitumen or bitumen and scrap polymer, and tiles using recycled PVC.


The environmental impact – analysis and observations There is a general trend of improving environmental performance with increased recycled content in carpet tiles. This is the case for both kg CO2 eq.(100 years) and Ecopoints (see Figures 2.13.1 and 2.13.2). As a general rule of thumb, the principal environmental impacts of the carpet stem from the use of hydrocarbons (fossil fuels) in the materials used in the tiles (such as PVC, and nylon for the yarn); but also from the use of fossil fuels for the energy required in production of those same materials. The impacts in question are climate change (kg CO2 eq.(100 years)) and secondly fossil fuel depletion. Any reduction in the use of virgin materials in tile, therefore, reduces the hydrocarbon (fossil fuel) use and provides environmental performance improvements by reducing the climate change impact and the Ecopoint score. In consequence, based on the general trends shown by BRE’s available data sets, moving from standard to good practice recycled content in carpet tiles provides a reduction of 2.2 kg CO2 eq.(100

years) and 0.02 Ecopoints per m2. As with the other product Sections within this report, the environmental performance of carpet tiles with the same recycled content can be very different and therefore moving from one standard carpet tile to a good carpet tile might mean a different level of improvement to the levels shown above. The change could be better or worse than the stated figures.

Figure 2.13.1: Recycled content of generic carpet tiles vs kg CO2 eq. (100 years)

Carpet tiles

5

7

9

11

13

15

17

19

21

0 10 20 30 40 50 60 70 80 90 100

% recycled content

kg C

O2

equi

v

Bitumen & scrap polymer

No recycled content

Bitumen

Recycled PVCScrap carpet



Figure 2.13.2: Recycled content of generic carpet tiles vs Ecopoints

Carpet tiles

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

0 10 20 30 40 50 60 70 80 90 100

% Recycled input

Eco

poin

ts

Bitumen & scrap polymer

No recycled content

Bitumen

Recycled PVCScrap carpet


Transport Transport represents a small fraction of the overall impact of the average carpet tile being responsible for approximately 2% of kg CO2 eq.(100 years) and 2% of the Ecopoints per m2 of product. Therefore, the likely transport distances that the component materials are travelling are unlikely to alter the improvement in environmental performance from standard to good practice significantly.


2.14 Drainage pipes

Table 2.14.1: Recycled content levels Application Standard Good

PP 0 75

HDPE 20 45

PVC 0 10

Recycled content materials considered Recycled PP Recycled HDPE Recycled PVC Recycled copper Recycled PP

Statement of findings Due to lack of specific data on plastic drainage products, BRE have been unable to provide the same level of analysis of moving from standard to good practice recycled content in this Section. However, the following text touches upon some relevant work in this area and gives an indication of the possible findings were the study to be completed. The general findings of the research considered were that generally recycling plastics has some explicit advantages over landfilling or incineration; however, there can be cases where incineration would be preferable if washing of the plastics is required to recycle them. Product background Drainage pipes can be made of many different materials including vitrified clay, concrete, iron, copper, asbestos and a number of different plastics (PVC, HDPE and PP). Depending on the specific drainage application some of these materials are likely to be more commonly used or more appropriate than others; however, many of them can be used for the same applications and, therefore, compete directly in the market place. For example, HDPE and PVC are commonly used for land drainage pipes and PP and PVC are commonly used for soil and waste pipes. Analytical approach and data used BRE have no data sets for drainage pipes, therefore, BRE recognise this product category as a significant data gap within this project. However, there is a significant body of work that addresses the plastic material types in question. In May 2006 WRAP published “Environmental Benefits of Recycling: An international review of life cycle comparisons for key materials in the UK recycling sector”. The study was “the largest and most comprehensive international review of LCA work on key materials that are often collected for recycling – paper/cardboard, plastics, aluminium, steel, glass, wood and aggregates.”xxxii Of several hundred studies that were screened, 55 LCAs were selected for detailed review, comprising over 200 different scenarios, each one a LCA in its own right. In total the review covered 42 studies and 60 scenarios of high quality LCAs for plastics covering a variety of countries and the conclusions were in general believed to be robust. The report considered


PVC, PP, PE (both LDPE and HDPE) and PET and therefore one can assume a high degree of applicability to the materials that are considered in this product Section. (It is felt that although PET is not considered in the current report, its environmental performance characteristics are not likely to differ drastically from the other three plastics types.) The environmental impact categories that featured in the review included energy use, resource consumption, global warming potential, other energy-related impacts, toxicity, waste generation and other impacts such as on land use or biodiversity. The environmental impact – analysis and observations The majority of LCA studies used evaluated the environmental impacts from the replacement of virgin plastics with 100% recycled plastics in comparison to the environmental impacts that result from landfilling the waste plastic or incinerating it. It was concluded that in the majority of cases recycling and material recovery was environmentally better than both incineration and landfilling, with recycling being around 50% better on average (see Figure 2.14.1). The net CO2 saving from recycling was found to be 1.5 – 2 tonnes CO2 eq.(100 years) per tonne of plastics on average. In cases where the quality/grade of the recovered plastic implied a less favourable substitution ratio (worse that 1:1), the scenarios dealing with this issue demonstrated that a ratio of 1:0.5 was about the break-point at which recycling and incineration with energy recovery were environmentally equal. In scenarios where washing and cleaning was needed, the scenarios dealing with this demonstrated that this may lead to incineration being environmentally preferable to recycling. The reason was the need for hot water for washing and the fact that the organic contaminants have a heat value that is an advantage in the incineration scenarios, but a disadvantage in recycling, because the removal of contaminants in municipal wastewater treatment required energy. However, the study also points out that the energy used depends on the temperature required and the nature and extent of the contaminants in question.


Figure 2.14.1: Frequency histograms of the distribution of results from the various scenarios of the reviewed studies showing the saved emissions of greenhouse gases from recycling vs. incineration and landfill respectively. A negative value (the left side of the diagram means that recycling causes a saving compared to incineration or landfill).


Figure 2.14.2: Relative difference in impact from recycling vs. incineration. A negative value means that recycling causes less impact than incineration.

There are a number of drainage pipe producers in the UK that use recycled bottles supplied from bottle collection schemes. The bottles do require cleaning to remove labels, liquids and organic compounds prior to being chipped and melted to form new pipe products. Although, according to the LCA study purely on a energy consumption basis the associated washing may mean that it is better to incinerate the plastic rather than wash it for use, there are other factors to take into consideration not least the lack of accurate measurements in the UK of the energy required for the cleaning of waste plastics that can be used for drainage pipes. Transport Most plastic products in the UK, including drainage pipes, are made using petrochemicals that are imported from outside UK borders. By reducing the consumption of petrochemicals by substituting them with recycled plastics this reduces the transport burden of the petrochemicals that are brought into the UK. Currently there is a significant demand in other countries for recycled plastics that is making the export of our plastic wastes a viable activity. Government figures in 2004 estimated that around 200,000 tonnes of plastic waste was being sent to China and 40% to 60% of the waste plastic bottles collected in the UK were a significant part of that 200,000 tonnes.xxxiii If an increased demand can be created in the UK this will reduce the transport burden associated with the moving of British waste plastics to other countries and may improve the environmental performance of overall plastics recycling associated with the UK. However, quantifiable data on the kg CO2 eq.(100 years) and Ecopoints results for these different activities have not been produced and, therefore, definitive conclusions and recommendations cannot be made at this point.


3 Case studies

Statement of findings Case studies have been analysed to estimate the overall impact of moving from standard to good practice recycled content across the “Quick Win” product categories for each project (e.g. in response to a client requirement). It was found that, for all but one of the case studies, in all the environmental performance criteria, kg CO2 eq. (100 years), Ecopoints and landfill/overburden, there was a significant benefit by moving from standard to good practice recycled content in the Quick Win categories. This was particularly true for the Ecopoint and landfill/overburden results. The one exception was case study 13, the widening of the M25, for which increasing the level of recycled content reduced the Ecopoint score but increased the associated carbon emissions. However, this carbon result is based on generic assumptions about the delivery distances of recycled and primary aggregate to the construction site. In practice, the M25 widening used recycled aggregate for around 90% of the unbound aggregate requirement, over 800,000 tonnes in total. Reuse of materials arising on site accounted for 35% of the total tonnage; the other 65% was sourced from the local London area, and had a £4/tonne cost advantage over comparable free-draining primary aggregates which would have had to be imported some distance from the Mendips or Leicestershire. Section 2 of this report identifies that reuse on site has a carbon advantage over primary aggregate, and sourcing recycled aggregate by road at least 10km closer to the site than virgin crushed rock would cancel out the carbon disadvantage of the average aggregate recycling plant. Therefore, in practice, the use of recycled aggregate on this project could be seen to have had a carbon benefit. In the case of the kg CO2 eq. (100 years) outcomes, the concrete products (with the exception of dense blocks) were shown to produce the greatest reduction in emissions due to the possible replacement of the “carbon heavy” cement with the substances PFA or GGBS. By applying general trends from Section 2 of this report on average primary aggregates and recycled aggregates, moving from standard to good practice in this case would increase kg CO2 eq. (100 years) emissions. However, BRE recognise that the research of aggregates as a whole would benefit from a more thorough collection of data. On the other hand recycled aggregates were found to have significant benefits for both Ecopoint and landfill/overburden environmental performances. Section 2 identifies those situations where sourcing recycled aggregates more locally than virgin aggregates would give the recycled aggregate a carbon advantage, reversing the general trend. Analytical approach and data used This Section looks at a number of case studies that represent typical construction types in the UK and covers 12 buildings in total and two civil engineering projects. The information on materials used and their volumes has been sourced from WRAP’s extensive list of case studies, generally based on post-construction assessment of real-life projects. Only a limited set of the materials used in the buildings are considered, focusing on the product categories considered in this report and on those product substitutions in each case study which dominate the potential improvement in recycled content for the project as a whole (i.e. the Quick Wins for that project). Table 3.1 below lists the chosen case studies and gives the total kg CO2 eq. (100 years), Ecopoint and landfill and/or overburden savings or gains for each of them that could result by moving from standard to good practice recycled content. For the kg CO2 eq. (100 years) and Ecopoints differences, the average trends from the preceding product category


sections have been applied. For the landfill and overburden analysis only the input materials that would otherwise be sent to landfill or be placed in overburden strips by moving from standard to good practice recycled content have been considered. Each case study has a more detailed table with the list of products considered and the results. On completing the individual case study analyses, a hypothetical upscaling of the result for the domestic builds up to a national scale was undertaken to demonstrate possible savings or gains due to moving from standard to good practice recycled content in new builds across the UK. The results are presented in Table 3.2 below. However, this makes the assumption that the buildings used typify their respective build types, which may be broadly true but is unlikely to be a completely accurate evaluation. Therefore, the upscaling exercise should be regarded as very approximate and more of a valuable exercise in thinking about the potential environmental impact reductions that could be achieved nationally were such a policy implemented. Note: Some the product categories in each case study are reported to have zero difference in kg CO2 eq.(100 years) or Ecopoints by moving from standard to good practice recycled content. This result reflects the findings in the corresponding previous Sections, where either the trend data do not show a significant variation with recycled content, or the underlying data have been inadequate to support a robust conclusion.

Environmental impact of higher recycled content in construction projects 92 Table 3.1 Case study listing and environmental performance results by

moving from standard to good practice recyled content across project in Quick Win categories

Total kg CO2 equiv (100 yrs) difference

Total Ecopoints difference

Total landfill or overburden difference

Timber frame build typesCase study 1 Timber frame semi-detached house (144m2) -4,252 -32 -13Case study 2 Three storey timber frame flats (3,730m2) -14,524 -690 -172

Brick and block build typesCase study 3 3 bedroom terraced brick and block house (105m2) -474 -366 -13

Steel frame build typesCase study 4 Steel frame house 2 storey (68m2) -172 -22 -11Case study 5 Lightweight steel frame flats 3 stories (102m2) -1,542 -98 -32Case study 6 Steel frame commercial building (6631m2) -514,464 -13,252 -5,903Case study 7 Steel frame office (1270m2) -4,477 -67 -12Case study 8 Steel frame hospital (NAm2) -327,491 -3,985 -4,476Case study 9 Steel frame primary school (4128m2) -2,880 -29 -4Case study 10 Tertiary Education Halls of Residence (10,900m2) -40,636 -18,902 -5,349

Concrete frame build typesCase study 11 Concrete frame apartment block 9 stories (14,947m2) -669,667 -6,092 -1,042Case study 12 Concrete frame office 7 stories (19,049m2) -671,847 -12,124 -31

Civil engineering build typesCase study 13 M25 1,874,730 -428,298 -2,266Case study 14 Highways Improvement Case Study - Bridge Construction -71,468 -5,194 -2,043


Overview of findings It was found that for all but one of the case studies considered there were kg CO2 eq.(100 years), Ecopoint and landfill and overburden benefits by moving from standard to good practice recycled content. The greatest opportunity for reductions in environmental impact as a consequence of moving from standard to good practice recycled content were found in the concrete products and in particular in RMC, due to its use in large volumes and application in almost all UK build types, whether in elements such as foundations, ground floors, walls or the building structure itself. The Quick Win materials used in smaller quantities, such as drainage products, comparatively will have a much smaller influence on the overall embodied environmental performance of the projects in question. Nonetheless, such categories provide good opportunity to use recycled material, reduce landfill and/or overburden and in the main have not been shown to increase other environmental impacts significantly, and in many cases actually reduce them. It is not advised that comparisons be made using the data presented here between the different build approaches, such as between timber frame and brick and block, because the total environmental impacts of the different build types are not presented; it is merely the difference between standard and good practice within each case study example that should be considered. Additionally, the buildings used are only indications of their build type and the level of information on the materials used for each, although fairly comprehensive, may be more accurate for some than others.


Timber frame build types

Material

Kg CO2 eq.(100 years) difference by moving from standard to good pratice recycled content

Area (m2) or other unit where specified

Total Kg CO2 eq.(100 years) difference

Ecopoint difference by moving from standard to good pratIce recycled content


Total Ecopoint difference

Landfill or overburden material saved by moving from standard to good practice recycled content

Landfill or overburden material saved by moving from standard to good practice recycled content as % of total weight

Tonnage saved

% of total landfill saving

Asphalt -0.22 117 -25.7 -0.03 117 -3.5 Asphalt planings 14 -0.18 1.38%Reinforced in-situ concrete 150mm, C30 or higher -20.52 151 -3098.5 -0.1332 151 -20.1Fibre Cement Slates -1.5 174 -261 -0.014 174 -2.4 CWD 5 -0.31 2.36%upvc gutters 0 50m 0 0 50m 0.0 Post consumer uPVC 10 -0.0025 0.02%Glass wool 200mm 0 144 0 0 144 0.0Mineral wool insulation, 100mm 0 128 0 0 128 0.0Plasterboard 0 128 0 0 128 0.022 thick chipboard flooring 0 144 0 0 144 0.0 Various wood waste 5 -0.11 0.82%Surface drainage PVC pipe 0 141m 0 0 141m 0.0 Waste concrete blocks 30 -2.77 21.10%Concrete paving slab (50mm pedestrian) -25 24 -600 -0.15 24 -3.6 China clay waste 45 -9.77 74.32%Plasterboard and plaster 0 144 0 0 144 0.0EPS (50mm) - zero ozone depletion potential -1.85 144 -266.4 -0.018 144 -2.6 Post consumer EPS 25 -0.36 2.74%

TOTAL RESULTS

Total Kg CO2 eq.(100 years) difference -4,252

Total Ecopoints difference -32

Total tonnage saved -13 100%

Kg CO2 eq.(100 years), Ecopoint and landfill savings at material, building and national levels by moving from standard to good practice recycled content

Table 3.3: Case study 1 - Timber frame semi-detached house (144m2)

The greatest environmental benefits achievable by increasing recycled content in the timber frame semi-detached house are attributable to in-situ C30 RMC and concrete paving slabs. The C30 RMC is responsible for 72% of the reduction in carbon emissions and 25% of the reduction in Ecopoints. There is deemed to be no resultant reduction in landfill or overburden by using good practice C30 RMC as the recycled content of 7% is wholly made up of cement replacement material, for which demand for use in construction outstrips supply in the UK. The concrete paving slabs are responsible for 14% of the reduction in carbon emissions, 11% of the reduction in Ecopoints and 74% of the landfill and overburden saving.


Material









Tonnage saved


Asphalt road -0.22 1800 -396 -0.03 1800 -54 CDW & Asphalt planings 14 -158.76 92.13%C25 RMC ground floor (150mm) -7.2 1388 -9994 -0.0864 1388 -120 CDW 20 -9.99 5.80%EPS (50mm) - zero ozone depletion potential -1.85 1388 -2568 -0.018 1388 -25 Post consumer EPS 25 -0.35 0.20%Mineral fibre ceiling tiles -0.7 329 -230 0.008 329 3 Mineral & glass insulation waste 20 -0.16 0.10%Mineral wool insulation (55mm) 0 1399 0 0 1399 0Mineral wool insulation (75mm) 0 1399 0 0 1399 0Glass wool (200mm) 0 1388 0 0 1388 0Clay facing bricks 0 1399 0 0 1399 0Lightweight concrete blocks (100mm) 0 120 0 -4 120 -480 Waste concrete blocks 15 -1.39 0.80%Plasterboard (12.5mm) 0 7526 0 0 7526 0uPVC gutters 0 231m 0 0 231m 0 Post consumer uPVC 10 -0.01 0.01%Carpet -2 668 -1336 -0.02 668 -13 Scrap polymer, carpet & PVC 50 -1.65 0.96%

TOTAL RESULTS


Total Ecopoints saved -690


Table 3.4: Case study 2 - Three storey timber frame flats (3,730m2)Kg CO2 eq.(100 years), Ecopoint and landfill savings at material, building and national levels by moving from standard to good practice recycled content

The greatest environmental benefits achievable by increasing recycled content in the three storey timber frame flats are attributable to the C25 RMC ground floor and the EPS insulation. The C25 RMC ground floor is responsible for 69% of the reduction in carbon emissions, 17% of the reduction in Ecopoints and 6% of the landfill and overburden saving; the EPS insulation is responsible for 18% of the reduction in carbon emissions, 3.6% of the reduction in Ecopoints but less than 1% of the landfill and overburden saving; the lightweight concrete blocks are also worth mentioning and are responsible for 72% of the reduction in Ecopoints. Asphalt planings contribute significantly to Ecopoint and landfill savings.


Brick and block build types

Material









Tonnage saved


C25 RMC ground floor (150mm) -7.2 36 -259.2 -0.0864 36 -3.1104 CDW 20 -0.26 2%EPS (50mm) - zero ozone depletion potential -1.85 35 -64.75 -0.018 35 -0.63 Post consumer EPS 25 -0.01 0%Concrete roof tiles 0 80 0 -0.012 80 -0.96 CDW 10 -0.62 5%Mineral wool insulation (75mm) 0 250 0 0 250 0Clay facing bricks 0 120 0 0 120 0 Various 5 -0.9 7%Lightweight concrete blocks (100mm) 0 120 0 -3 120 -360 Waste concrete blocks 15 -1.39 11%Plasterboard (12.5mm) 0 147 0 0 147 0PVC pipe 0 15m 0 0 15m 0 Post consumer PVC 10 -0.01 0%Concrete paving slab (50mm pedestrian) -25 6 -150 -0.15 6 -0.9 China clay waste 45 -9.77 75%

TOTAL RESULTS

Total Kg CO2 eq.(100 years) difference -474



Table 3.5: Case study 3 - 3 bedroom terraced brick and block house (105m2) Kg CO2 eq.(100 years), Ecopoint and landfill savings at material, building and national levels by moving from standard to good practice recycled content

The greatest environmental benefits achievable by increasing recycled content in the 3 bedroom terraced brick and block house are attributable to the C25 RMC ground floor, the lightweight concrete blocks and the concrete paving slabs. The C25 RMC ground floor is responsible for 55% of the reduction in carbon emissions but less than 1% of the reduction in Ecopoints and about 2% of the landfill and overburden saving; the lightweight blocks are responsible for no reduction in carbon emissions but 98% of the reduction in Ecopoints and 10% of the landfill and overburden saving; finally concrete paving slabs are responsible for 32% of the reduction in carbon emissions, less than 1% of the reduction in Ecopoints and 74% of the landfill and overburden saving.


Steel frame build types

Material



Total Kg CO2

eq.(100 years) difference






Tonnage saved


General fill 3.5 16m3 56.6 -0.809 16m3 -12.944 CDW 25 -7.2 67%Reinforced in-situ concrete 150mm, C25 or lower -7.2 36 -259.2 -0.0864 36 -3.1104 CDW 20 -2.592 24%EPS (50mm) - zero ozone depletion potential -1.85 102 -29.6 -0.018 102 -1.836 Post consumer EPS 25 -0.03 0%Clay facing bricks 0 60 0 0 60 0 Various 5 -0.45 4%Mineral wool insulation (75mm) 0 60 0 0 60 0Plasterboard 0 24 0 0 24 0Dense concrete blocks 6 10 60 -0.4 10 -4 CDW 45 -0.41 4%

TOTAL RESULTS

Total Kg CO2

eq.(100 years) difference -172



Table 3.6: Case study 4 - Steel frame house 2 storey (68m2)Kg CO2 eq.(100 years), Ecopoint and landfill savings at material, building and national levels by moving from standard to good practice recycled content

The greatest environmental benefits achievable by increasing recycled content in the steel frame house are attributable to the C25 RMC, however, the carbon reduction benefit that it produces is partly negated by the poorer carbon performance of the higher recycled level in general fill unbound aggregate and the dense concrete blocks. Although the general fill has a disbenefit in carbon terms (on average, prior to transport to site), in Ecopoints, due to the reduction in minerals extraction, it produces around half of the reduction in Ecopoints. Additionally, the general fill also represents the greatest benefit for landfill and overburden savings at 67% of the reduction. The C25 RMC is responsible for 24% of the landfill and overburden savings.


Material



Total Kg CO2






Landfill or overburden material saved by moving from standard to good practice recycled content as % of total weight Tonnage saved


General Fill 3.5 50m3 177 -0.809 50m3 -40.45 CDW 25 -30.00 92.43%Trench block, Dense 6 100 600 -0.4 100 -40 CDW 20 -1.80 5.55%Reinforced in-situ concrete 150mm, C30 or higher -20.52 74 -1518 -0.1332 74 -9.9Expanded polystrene (EPS) zero ODP 50mm -1.85 291 -538 -0.018 291 -5.2 Post consumer EPS 25 -0.07 0.22%Clay facing bricks 0 36 0 0 36 0 Various 5 -0.27 0.83%Mineral wool insulation, 75mm 0 57 0 0 57 0Plasterboard 0 100 0 0 100 0Mineral wool insulation, 75mm 0 57 0 0 57 0Gypsum fire resistant plasterboard 12.5mm double layer 0 100 0 0 100 0Gypsum Soundblock plasterboard 15mm double layer 0 100 0 0 100 0Gypsum wallboard 15mm double layer 0 100 0 0 100 0Gypsum fire resistant plasterboard 0 100 0 0 100 0Non slip vinyl flooring -2 75 -150 -0.02 75 -1.5 Scrap polymer, carpet & PVC 50 -0.13 0.41%Wool carpet, natural fibre -2 56 -112 -0.02 56 -1.12 Scrap polymer, carpet & PVC 50 -0.18 0.55%

TOTAL RESULTS

Total Kg CO2

eq.(100 years) difference -1542



Table 3.7: Case study 5 - Lightweight steel frame flats 3 stories (102m2) Kg CO2 eq.(100 years), Ecopoint and landfill savings at material, building and national levels by moving from standard to good practice recycled content

The greatest environmental benefits achievable by increasing recycled content in the lightweight steel frame flats are attributable to the C30 RMC and the EPS insulation, however a significant portion of the carbon reduction benefit that they and the other products produce is cancelled out by the poorer carbon performance of the higher recycled level in general fill unbound aggregate (prior to transport to site) and the dense trench concrete blocks. All of the products have a benefit in Ecopoint terms with an increase in recycled content, but the greatest benefit comes from the use of recycled aggregate general fill. The general fill also provides the greatest opportunity for reducing landfill and overburden.


Material









Tonnage saved


Site capping 3.54 3976m3 14075 -0.809 3976m3 -3217 CDW 25 -1789 30%Type 1 Sub-base under external slab 3.54 4675m3 16550 -0.809 4675m3 -3782 CDW 25 -2104 36%Type 2 Sub-base under internal slab 3.54 995m3 3522 -0.809 995m3 -805 CDW 25 -448 8%Type 1 Road sub-base 3.54 340m3 1204 -0.809 340m3 -275 CDW 25 -153 3%Pipe backfill (Class 8) for Effluent and Carrier Drainage 3.23 215t 694 -0.8358 215t -180 CDW 25 -54 1%Pipe backfill for French Drains 3.23 95t 307 -0.8358 95t -79 CDW 25 -24 0%Pipe surround (ST2 Concrete) for Carrier Drainage 3.23 3m3 10 -0.8358 3m3 -3 CDW 25 -1 0%Pipe surround (Type A) for French Drains 3.23 46t 149 -0.8358 46t -38 CDW 25 -12 0%

Pipe surround (Type B) for Effluent Drainage 3.23 233t 753 -0.8358 233t -195 CDW 25 -58 1%Asphalt -0.09 1945 -175 -0.432 1945 -840 Asphalt planings 14 -172 3%Concrete for internal ground slab, cast in situ, C30 or higher, excluding reinforcement -136.8 1326m3 -181397 -0.888 1326m3 -1177 CDW 7 -223 4%

Concrete walls below steel frame and cladding, in situ C30 or higher, excluding reinforcing -136.8 484m3 -66211 -0.888 484m3 -430 CDW 7 -81 1%Concrete foundations for retaining walls, C30 or higher, no reinforcement -136.8 16m3 -2189 -0.888 16m3 -14 CDW 7 -3 0%Concrete retaining walls, C30 or higher, excluding reinforcement -136.8 63m3 -8618 -0.888 63m3 -56 CDW 7 -11 0%Blinding concrete for external pavement -48 977m3 -46896 -0.576 977m3 -563 CDW 20 -469 8%External concrete pavement slab, cast in-situ, C30 or higher, excluding reinforcement -136.8 1800m3 -246240 -0.888 1800m3 -1598 CDW 7 -302 5%PVC Pipes for Carrier Drainage (No more than 1.5m depth) 0 12m 0 0 12m 0 Post consumer PVC 10 0 0%PVC Pipes for Effluent Drainage (No more than 1.5m depth) 0 600m 0 0 600m 0 Post consumer PVC 10 0 0%PVC Pipes for French Drains (No more than 1.5m depth) 0 132m 0 0 132m 0 Post consumer PVC 10 0 0%

TOTAL RESULTS


Total Ecopoints saved -13,252

Total tonnage saved -5,903 100%

Table 3.8: Case study 6 - Steel frame commercial single storey (6631m2) Kg CO2 eq.(100 years), Ecopoint and landfill savings at material, building and national levels by moving from standard to good practice recycled content

Environmental impact of higher recycled content in construction projects 100 A similar pattern emerges for case study 6, the steel frame commercial building, as with the preceding steel frame case studies, whereby some of the carbon emissions benefit produced by the increase in recycled content in some of the more important products, such as the RMCs, is cancelled out by the greater carbon emissions associated with the average recycled aggregate compared to the average primary aggregate (prior to transport to the construction site). However, in this case the volume of concrete used is so significant that the accumulated benefits are still substantial even with the extra carbon load of the recycled aggregate. On an Ecopoint basis both the concrete and the aggregates have significant benefits associated with using higher recycled content. Finally, the recycled aggregate produces 78% of the reduction in landfill and overburden for the entire build. Most of the concrete at strength C30 or above has been considered to use only cement replacement as recycled content and not recycled aggregate, and the former of these is not sent to landfill or overburden in the UK as almost all of it is used in construction material.


Material



Total Kg CO2







Tonnage saved % of total landfill saving

General Fill 3.54 20m3 71 -0.809 20m3 -16.2 CDW 25 -9.0 79%In-situ concrete BS5328, C30 or higher, 150mm -20.52 125 -2565 -0.1332 125 -16.7Reinforced in situ concrete C30 or higher, 225mm -30.78 72 -2216 -0.1998 72 -14.4

upvc gutters 0 21m 0 0 21m 0.0Scrap polymer, carpet & PVC 10 0.0 0%

Glass wool 60mm 0 5 0 0 5 0.0Facing bricks 0 58 0 0 58 0.0 Various 5 -0.4 4%Glass wool insulation 100mm 0 7 0 0 7 0.0Cavity block construction; inner skin dense concrete blocks 6 49 294 -0.4 49 -19.6 CDW 45 -2.0 17%

Carpet (generally) -2 12 -24 -0.02 12 -0.2Scrap polymer, carpet & PVC 50 0.0 0%

Mineral fibre ceiling tile -0.7 23 -16 0.008 23 0.2 Mineral & glass insulation 20 0.0 0%Expanded polystrene (EPS) zero ODP 50mm -1.85 11 -20 -0.018 11 -0.2 Post consumer EPS 25 0.0 0%

TOTAL RESULTS

Total Kg CO2

eq.(100 years) difference -4,477


Total tonnage saved -11.5 100%


Table 3.9: Case study 7 - Steel frame office (1270m2)

The greatest environmental benefits achievable by increasing recycled content in the steel frame office are attributable to the in-situ C30 RMC, which represents nearly all the gross reduction in carbon emissions. However, 8% of this improvement is cancelled out by the greater carbon burden attributed to good practice dense blocks and general fill compared to their standard practice alternatives. On the other hand, good practice recycled content achieves a reduction in Ecopoints for general fill, dense blocks as well as the concrete, carpet and expanded polystyrene. Despite its adverse average performance on carbon emissions, the general fill saves 79% of the total landfill and overburden savings.


Material









Tonnage saved


General Fill 3.54 516m3 1827 -0.809 516m3 -417 CDW 20 -186 4%Asphalt -0.22 2897 -637 -0.03 2897 -87 CDW & Asphalt planings 38 -694 15%Reinforced in-situ concrete 250mm, C30 or higher -34.2 3156 -107935 -0.222 3156 -701Structural screed min 75mm thick to concrete -3.6 2197 -7909 -0.0432 2197 -95 CDW 20 -791 18%Structural screed min 85mm thick to concrete -4.08 528 -2154 -0.04896 528 -26 CDW 20 -215 5%Concrete in foundations, cast in-situ excluding reinforcing, C25 or lower -48 27m3 -1296 -0.576 27m3 -16 CDW 20 -13 0%Concrete in foundations, cast in-situ excluding reinforcing, C30 or higher -136.8 360m3 -49248 -0.888 360m3 -320Concrete in foundations, cast in-situ, including reinforcing and formwork, C30 or higher -136.8 463m3 -63338 -0.888 463m3 -411Concrete block paving 0.03 1015 30 -0.015 1015 -15 China clay waste 45 -29 1%Upper floors, Concrete in situ, Cast in situ concrete slab - Long span (6m) -20.52 3663 -75165 -0.1332 3663 -488Structural screed min 75 thick to concrete and smooth trowelled finish, allow for mesh reinforcement -3.6 5269 -18968 -0.0432 5269 -228 CDW 20 -2529 57%Mineral wool insulation, 150mm 0 2736 0 0 2736 0Plasterboard - to steel stud partition 15mm 0 28339 0 0 28339 0Lightweight blockwork 0 404 0 -3 404 -1212 Waste concrete blocks 15 -5 0%2.5mm Linoleum; fixed with adhesive to cement sand screed, incl levelling latex and protection (circulation, labs & stores) 0 4663 0 0 4663 0 Scrap polymer, carpet & PVC 50 -11 0%Anti static vinyl flooring fixed with adhesive to cement sand screed, incl earth tape, earthing, latex levelling screed and protection (wet areas) -2 31 -62 -0.02 31 -1 Scrap polymer, carpet & PVC 50 -1 0%Non slip vinyl flooring fixed with adhesive to cement sand screed, incl latex levelling screed and protection (wet areas) 0 284 0 0 284 0 Scrap polymer, carpet & PVC 50 0 0%Plasterboard on M/F systems 0 1124 0 0 1124 0Suspended ceiling, exposed mineral wool tile -0.7 3764 -2635 0.008 3764 30 Mineral & glass Insulation waste 20 -2 0%

TOTAL RESULTS




Kg CO2 eq.(100 years), Ecopoint and landfill savings at material, building and national levels by moving from standard to good practice recycled contentTable 3.10: Case study 8 - Steel frame hospital

Environmental impact of higher recycled content in construction projects 103 When comparing the case studies some common patterns become apparent, especially in the larger multi-unit buildings. The concrete products offer the greatest environmental benefits in carbon emissions reduction and the recycled aggregates go some way to reducing this benefit but at the entire building level do not completely negate the benefit. The greatest environmental benefits achievable by increasing recycled content in the steel frame hospital are attributable to the in-situ C25 and C30 RMC and the structural screed, which represent approximately 70% of the total reduction in carbon emissions. Although these concrete products also contribute significantly to reducing the Ecopoint score, the single largest reduction in Ecopoints at 30% is produced by the use of good practice lightweight blocks. Finally, unlike in the other larger building case studies where the unbound aggregate creates the greatest reduction in landfill and overburden, in the steel frame hospital the concretes and screeds give 80% of the savings in this regard.

Environmental impact of higher recycled content construction projects 104

Material









Tonnage saved % of total landfill saving

Common bricks half brick thick 0 127 0 0 127 0 Various 5 -0.5 11%Facing bricks 0 59 0 0 59 0 Various 5 -0.4 10%Mineral wool insulation, 25mm 0 535 0 0 535 0Carpet (generally) -2 1440 -2880 -0.02 1440 -28.8 Scrap polymer, carpet & PVC 50 -3.5 79%

TOTAL RESULTS




Table 3.11: Case study 9 - Steel frame primary school 2 storey (4,128m2) Kg CO2 eq.(100 years), Ecopoint and landfill savings at material, building and national levels by moving from standard to good practice recycled content

For the steel frame primary school two out of the three listed Quick Win products (bricks and mineral wool insulation) produced non-definitive results in the current report. Carpet tiles are the only product that show beneficial results across the three environmental performance metrics, including provided 79% of the landfill saving.


Material



Total Kg CO2







Tonnage saved


Filling to excavations 3.54 40m3 142 -0.809 40m3 -32 CDW 25 -18 0%Filling to manholes 3.54 75m3 266 -0.809 75m3 -61 CDW 25 -34 1%Granular material 3.54 3619m3 12811 -0.809 3619m3 -2928 CDW 25 -1629 30%Granular material 3.54 341m3 1207 -0.809 341m3 -276 CDW 25 -153 3%Plain in-Situ Concrete foundations -48 4254m3 -204192 -0.576 4254m3 -2450 CDW 20 -1531 29%Concrete backfilling to manhole -20 59m3 -1180 -0.25 59m3 -15 CDW 20 -21 0%Concrete capping -20 402m3 -8040 -0.25 402m3 -101 CDW 20 -145 3%Concrete slabs -7.2 1623 -11686 -0.09 1623 -146 CDW 20 -118 2%Asphalt -0.22 3225 -710 -0.03 3225 -97 Asphalt planings & CDW 14 -284 5%Brickwork 0 7906 0 0 7906 0 Various 5 -59 1%Manhole - brickwork 0 32 0 0 32 0 Various 5 0 0%Brickwork walls 0 29 0 0 29 0 Various 5 0 0%Blockwork - Light 0 14 0 -3 14 -42 CDW 45 -1 0%Blockwork - Dense 6 31199 187194 -0.4 31199 -12480 CDW 45 -1264 24%Roof tiling 0 9278 0 -0.012 9278 -111 CDW 10 -72 1%Insulation 0 4058 0 0 4058 0Fire barriers - Rockwool 0 258 0 0 258 0Quilt Insulation 0 4854 0 0 4854 0Cavity insulation 0 3563m 0 0 3563m 0Insulation 0 6962 0 0 6962 0Insulation 0 274 0 0 274 0Plasterboard & skim 0 9021 0 0 9021 0Plasterboard 0 2799 0 0 2799 0Carpet -2 8224 -16448 -0.02 8224 -164 Scrap polymer, carpet & PVC 50 -20 0%Plastic drainage pipes 0 6264m 0 0 6264m 0 Post consumer PVC 10 0 0%

TOTAL RESULTS

Total Kg CO2

eq.(100 years) difference -40,636



Table 3.12: Case study 10 - Tertiary Education - Halls of Residence (10,900m2) Kg CO2 eq.(100 years), Ecopoint and landfill savings at material, building and national levels by moving from standard to good practice recycled content

For the halls of residence case study all the materials used (where conclusive results could be drawn in the main body of the report) provide an Ecopoint reduction by using higher recycled content. The key products that produce the greatest benefit in this regard are the unbound aggregates, the concrete and the dense and lightweight blocks. These products and the asphalt paving also represent the greatest opportunity for landfill and overburden savings. In terms of carbon emissions a significant benefit results at the building level from the use of higher recycled content in the poured concrete applications, although the use of higher recycled content in the aggregates and dense blocks reduce the total carbon reduction benefit significantly.


Concrete frame build types

Material










General fill 3.54 1961m3 6942 -0.809 1961m2 -1586 CDW 25 -882.00 85%Concrete in foundations, cast in-situ excluding reinforcing, C25 or lower -48 167m3 -8016 -0.576 167m3 -96 CDW 20 -80 8%Concrete in foundations, cast in-situ excluding reinforcing, C30 or higher -136.8 1425m3 -194940 -0.888 1425m3 -1265Reinforced in situ concrete C30 or higher, 225mm slab -30.78 14947 -460069 -0.1998 14947 -2986Expanded polystrene (EPS) zero ODP 50mm -1.85 1500 -2775 -0.018 1500 -27 Post consumer EPS 25 -2 0%Plasterboard - to stud partition 12.5mm 0 5218 0 0 5218 0Carpet (generally) -2 5427 -10854 -0.02 5427 -109 Scrap polymer, carpet & PVC 50 -13 1%VC (including waste pipework) 0 584m 0 0 584m 0 Post consumer VC 10 0 0%Surface drainage PVC pipe 0 1500m 0 0 1500m 0 Post consumer PVC 10 0 0%Concrete block paving 0.03 1500 45 -0.015 1500 -23 China clay waste 45 -65 6%Plasterboard on M/F systems 0 12574 0 0 12574 0

TOTAL RESULTS




Table 3.13: Case study 11 - Concrete frame apartment block 9 stories (14,947m2) Kg CO2 eq.(100 years), Ecopoint and landfill savings at material, building and national levels by moving from standard to good practice recycled content

For the concrete frame apartment block case study all the materials used (where conclusive results could be drawn in the main body of the report) provide an Ecopoints reduction by using higher recycled content. The key product that produces the greatest benefit in this regard is the concrete, in the form of C25 and C30 RMC. The general fill aggregate also provides significant Ecopoint reduction by using recycled aggregate but the same aggregate produces increased carbon emissions (prior to transport to site). Nonetheless, the carbon emissions reduction engendered by the use of good practice recycled content in concrete more than compensates and produces a very large reduction in carbon emissions. Finally, although the general fill aggregate has this environmental benefit/disbenefit dichotomy, it also represents the greatest reduction in landfill and overburden savings at 85% of the total savings.


Material










Reinforced in situ concrete C30 or higher, 300mm slab -41 16328 -670101 -0.2664 16328 -4350Mineral wool insulation, 100mm 0 400 0 0 400 0Lightweight concrete blockwork 100mm 0 2598 0 -3 2598 -7794 Waste concrete blocks 15 -30 98%VC (including waste pipework) 0 135m 0 0 135m 0 Post consumer VC 10 0 0%Mineral fibre tiles -0.7 2494 -1746 0.008 2494 20 Mineral & glass Insulation waste 10 -1 2%Plasterboard 12.5mm 0 3942 0 0 3942 0

TOTAL RESULTS




Kg CO2 eq.(100 years), Ecopoint and landfill savings at material, building and national levels by moving from standard to good practice recycled contentTable 3.14: Case study 12 - Concrete frame office 7 stories (19,049m2)

All the Quick Win products used in the concrete frame office case study produce (where data were sufficient) environmental benefits across all the metrics, carbon emissions, Ecopoints and landfill and overburden, when specified with good practice recycled content as opposed to standard practice recycled content, with the exception of mineral fibre tiles that cause a slight increase in Ecopoints; however it should be noted that this is an insignificant change (>0.1%) compared to the improvement produced by the other products. The lightweight concrete blockwork provides the greatest benefit in Ecopoints but has no benefit in terms of carbon emissions. The C30 concrete slab gives 99% of the carbon emissions benefit.


Infrastructure case studies

Material

Kg CO2 eq.(100 years) difference by moving from standard to good pratice recycled content / tonne Weight (tonnes)


Ecopoint difference by moving from standard to good pratIce recycled content / tonne Weight (tonnes)




Tonnage saved


General fill Class 1A 2.5 250000 632500 -0.58 250000 -144500 CWD 25 -186 8%Capping Classes 6F1 and 6F2 2.5 85000 215050 -0.58 85000 -49130 CWD 25 -694 31%Starter layer Classes 6A and 6C 2.5 125000 316250 -0.58 125000 -72250 CWD 25 -158 7%Backfill Class 6P 2.5 110000 278300 -0.58 110000 -63580 CWD 25 -791 35%Unbound sub-base Types 1 and 4 2.5 115000 290950 -0.58 115000 -66470 CWD 25 -215 10%Drainage fill 2.5 56000 141680 -0.58 56000 -32368 CWD 25 -222 10%

TOTAL RESULTS

Total Kg CO2 eq.(100 years) difference 1,874,730

Total Ecopoints difference -428,298

Total landfill or overburden tonnage difference -2,266 100%


Table 3.15: Case study 13 - Widening of M25 junctions 12 to 15 and spur stage 2

The widening of the M25 junction case study is the only case study where raising the recycled content from standard to good practice recycled content at the project level is modelled as actually increasing the carbon emissions. In the other case studies, the use of concrete products effectively overcompensates for the poorer kg CO2 eq.(100 years) performance of recycled aggregate as opposed to primary aggregate. However, for the M25 case study all the materials are aggregate and therefore do not benefit from the presence of concrete products. However, it must be borne in mind that it is possible to source recycled aggregate with a lower carbon emissions load than some primary aggregates, in particular by sourcing the recycled aggregate more locally. However, according to the generic data used for this report, on an average basis recycled aggregate performs less well than primary with respect to carbon at the point of leaving the processing plant (factory gate). The Ecopoint, landfill and overburden benefits by using recycled content in this case study are significant, with a reduction of 428,298 Ecopoints and landfill and overburden saving of 2,266 tonnes. In practice, this project used recycled aggregate for around 90% of the unbound aggregate requirement, over 800,000 tonnes in total. Reuse of materials arising on site accounted for 35% of the total tonnage; the other 65% was sourced from the local London area, and had a £4/tonne cost advantage over comparable free-draining primary aggregates which would have had to be imported some distance from the Mendips or Leicestershire (a long road journey, or a comparable rail journey plus 19km by road from the nearest rail-head). Section 2 of this report identifies that reuse on site has a carbon advantage over primary aggregate, and sourcing recycled aggregate at least 10km shorter distance by road than primary aggregate would also give the former a carbon advantage. Therefore, in practice, the use of recycled aggregate on this project could be seen to have had a carbon benefit.


Material

Kg CO2 eq.(100 years) difference by moving from standard to good pratice recycled content / tonne Weight (tonnes)


Ecopoint difference by moving from standard to good pratIce recycled content / tonne Weight (tonnes)




Tonnage saved


Import of granular material 2.5 1120 2834 -0.58 1120 -647 CWD 25 -186 9%Class 6N granular material 2.5 2400 6072 -0.58 2400 -1387 CWD 25 -694 34%Imported fill class 6N 2.5 4227 10695 -0.58 4227 -2443 CWD 25 -158 8%Asphalt paving -0.5 1659 -760 -0.06 1659 -105 CWD 25 -791 39%In-situ concrete RC25 and below -20.0 234 -4672 -0.24 234 -56 CWD 25 -215 11%In-situ concrete RC30 and above -57.0 1502 -85637 -0.37 1502 -556

TOTAL RESULTS


Total Ecopoints difference -5,194

Total landfill or overburden tonnage difference -2,043 100%

Table 3.16: Case study 14 - Highways bridge improvement

The results for the highways bridge improvement case study are more akin to the results for a building case study than the preceding aggregates-dominated case study of the widening of the M25 junction. In the bridge improvement project, as in the other building projects, the use of concrete products effectively overcompensates for the poorer kg CO2 eq.(100 years) performance of an average recycled aggregate compared to an average primary aggregate (prior to transport to site). The result is that the total project sees a marked improvement in carbon emissions performance by reducing the kg CO2 eq.(100 years) burden. Where there is similarity with the other infrastructure case study is the significant and beneficial decreases in Ecopoints and landfill and overburden.


Approximate national upscaling exercise Part of the original scope of this report was to evaluate the environmental consequences at the national level of construction projects moving from standard to good practice levels of recycled content in their top ten product categories, e.g. as a result of wide adoption of client, policy and planning requirements. However, there are constraints on performing this task. Through the undertaking of the report, significant data gaps have been identified that it is hoped will be filled in similar subsequent studies. Also the findings are presented as general trends based on a limited number of data sets and the listing of the materials and products used is more comprehensive for some of the case studies than others. For these reasons, it is felt that estimating at a national level the aggregated benefits or disbenefits associated with increasing recycled content across different projects will produce results with a high degree of uncertainty. Nevertheless, indicating a likely approach for undertaking an upscaling of the environmental performance results produced in this report to a national scale is believed to be a valuable exercise in itself and any uncertainty can be factored in. In future research reducing the different sources of uncertainty, by filling data gaps, increasing the number of data sets used and, therefore, improving the national representativeness of the results, will greatly increase the confidence in the findings. An indicative approach to estimating at a national level the aggregated change in environmental impact from asking for higher recycled content on construction projects The National House-Building Council (NHBC) publishes house building statistics on a quarterly basis for all domestic unit “starts” and completions by their affiliated members (estimated to represent 80% of the UK domestic market). Some other data are also presented, such as median selling prices for new houses. The figures are broken down according to domestic unit type in Table 16 of the quarterly report, and whilst greater detail is not provided on the non-timber build approaches, the NHBC statistics present in Table 22, the “Timber Frame Market Share by House Type in Great Britain”. In 2005, timber frame build represented 16% of the semi-detached starts in Great Britain, which is equivalent to 3,808 of the total 170,000 domestic starts listed by the NHBC for 2005. If we apply Case Study 1: Timber frame semi-detached house (144m2) to this number of starts in 2005, the following results can be modelled (and are presented together with an explanation of the uncertainty factors). Number of timber frame semi-detached starts in 2005 (UK) that were good practice Since construction products with above-average recycled content are readily available in the market from mainstream manufacturers, it is a reasonable assumption that a significant proportion of timber frame semi-detached homes that were started in the UK in 2005 would have demonstrated higher levels of recycled content than standard practice. Accurate recording of this data is currently not available (although, in England, the Government is now required to report every two years on increases in recycled content in the building stock). Therefore, an assumption has been made to the likely number of timber frame semi-detached houses at the higher levels of recycled content: 10% of the total starts have been assumed to be at good practice or above, and it has been assumed that 90%, or 3,427 units, could achieve a cost-neutral change in practice from standard recycled content to good recycled content. The uncertainty factors

Data sets used: A limited number of industry data sets were used, ranging from 1 to 30 data sets, for most of the Quick Win products to produce the results in this report. Some results, such as those for asphalt paving, combine industry data sets to produce them. Ideally more data sets would have been available, however, to date it has been neither practical (as a national system of recording data is not in place) nor economically viable for many companies to collate the required environmental impact data. The consequence is that an incomplete number of data sets has been used to represent a chosen product across the UK that comes from a much greater number of manufacturing facilities than the data sets provide data for. Applying an uncertainty factor for this is problematic and requires an appreciation of the representativeness of each Quick Win category.


Although the quality of the data varies between average and good according to factors such as age and geography, it is felt that for all the Quick Win categories that have permitted results to be calculated, a 20% level of uncertainty can be applied. This is assumed to equate to a 20% level of uncertainty for a single building unit and therefore a 20% increase or decrease in the result.

General trend only: Perhaps the most significant area of uncertainty, which is related to the number

of data sets used, is that of the general trends that have been produced. The graphs shown in the report not only show the general trends but also the groupings of products or ranges specific to given recycled content levels. For example, the data sets for granular fill or sub-base at no recycled content have a range that goes from approximately 20% below and 20% above the point on the general trend line (see graph below). Similarly, the data sets for granular fill or sub-base at 100% recycled content have a range that goes from approximately 30% below and 30% above the point on the general trend line. Taking an average of these two percentage ranges gives a 25% range above and below the general trend line.


0

2

4

6

8

10

12

0 20 40 60 80 100

% Recycled content

kg C

O2

equi

v


range


& range


The ranges for all the Quick Win products that used industry data sets varied between +/-10% and +/-55% for the kg CO2 eq.(100 years) results, with an average of +/-27%, and between +/-8% and +/-40% for the Ecopoint results, with an average of +/-25%. These figures have been used in the final calculations.

Products missing definitive results: It has been shown in the report that it has not been possible to produce results for all the Quick Win product categories; plasterboard and chipboard are two examples. However, whilst these materials are included in the case study and they could produce benefits or disbenefits it is difficult to assume a likely level of change in environmental performance if they were included. For this reason no adjustment has been included. Nevertheless, this is an important factor that should be noted.

Summary of uncertainty factors For Kg CO2 eq.(100 years) results: (Data sets used = +/- 20%)+(General trend only = +/- 27%) = Total uncertainty factor of +/-47% For Ecopoints results: (Data sets used = +/- 20%)+(General trend only = +/- 25%) = Total uncertainty factor of +/-45%

The above approach provides a means of factoring in the potential levels of uncertainty in approximating the environmental change in performance of using higher recycled content in building

+/-20% range

+/-30% range


types across the UK. There may be more appropriate ways of achieving this that might be used in the future, however, for the current study this has been deemed as a workable approach for the exercise. The results are shown in Table 3.17 below and explained further in the subsequent text. Note: Reduced levels of uncertainty apply to the calculation of landfill and overburden savings that can be achieved by moving from standard to good practice recycled content at the national level. These are informed by what materials are commonly landfilled or stockpiled as overburden on-site or at quarries and the accurately calculated difference in recycled content weight between standard and good practice.


Material









Tonnage saved


Asphalt -0.22 117 -25.74 -0.03 117 -3.51 Asphalt planings 14 -0.18 1.38Reinforced in-situ concrete 150mm, C30 or higher -20.52 151 -3098.52 -0.1332 151 -20.1132Fibre Cement 'Slate' -1.5 174 -261 -0.014 174 -2.436 CDW 5 -0.31 2.36upvc gutters 0 50m 0 0 50m 0 Post consumer uPVC 10 -0.0025 0.02Glass wool 200mm 0 144 0 0 144 0Mineral wool insulation, 100mm 0 128 0 0 128 0Plasterboard Lining 0 128 0 0 128 022 thick chipboard flooring 0 144 0 0 144 0 Various wood waste 5 -0.11 0.82Surface drainage PVC pipe 0 141m 0 0 141m 0 Waste concrete blocks 30 -2.77 21.10Concrete paving slab (50mm pedestrian) -25 24 -600 -0.15 24 -3.6 China clay waste 45 -9.77 74.32Plasterboard and plaster 0 144 0 0 144 0EPS (50mm) - zero ozone depletion potential -1.85 144 -266.4 -0.018 144 -2.592 Post consumer EPS 25 -0.36 2.76

TOTAL RESULTS


Total Ecopoints difference -32

Total landfill or overburden tonnage difference -13 100

Assumed total number of timber frame semi-detached starts at standard practice in UK in 2005 (based on NHBC housing statistics).

Without uncertainty factor (UF)

Total Tonnes CO2 eq.(100 years) difference for 3427 units UF = 0 -14,570

Total Ecopoints difference for 3427 units UF = 0 -110,525

Total landfill or overburden tonnage difference for 3427 units UF = 0 -45,027

With uncertainty factor (UF)

Total Tonnes CO2 eq.(100 years) difference for 3427 units UF = +/-47%

Between -7,722 and -21,419

Total Ecopoints difference for 3427 units UF = +/-45%

Between -60,789 and -160,261

Total landfill or overburden tonnage difference for 3427 units UF = 0 -45027

Table 3.17: National upscaling of results of Case study 1 - Timber frame semi-detached house (144m2) Kg CO2 eq.(100 years), Ecopoint and landfill savings at material, building and national levels by moving from standard to good practice recycled content


Analysis of results By changing the recycled content of 90% of timber frame semi-detached home starts over 1 year in the UK, significant environmental benefits can be achieved. According to Table 3.17, if good practice is adopted in the top ten product categories for higher recycled content, between 8 ktonnes and 21 ktonnes of CO2 eq.(100

years) emissions could be saved; between approximately 61,000 Ecopoints and 160,000 Ecopoints could be saved; and finally, approximately 45 ktonnes of landfill or overburden material can be saved. It is estimated that the average UK citizen is responsible for emitting at least 12.3 tonnes of CO2 eq.(100 years) emissions annually and is additionally responsible for environmental impacts, over the same period, equivalent to 100 Ecopoints. Also according to the Department of Environment, Food and Rural Affairs (DEFRA) the UK produced 17.9 million tonnes of municipal waste over the financial year 2005/2006. This equates to approximately 300kg of municipal waste for each of the 60.2 million UK citizens estimated by the Office of National Statistics that live in the UK. Therefore, the benefits from the chosen cost-neutral change in practice in recycled content across one of the build types in the UK, according to the results of this report, would correspond to:

Cancelling out the carbon emissions (kg CO2 eq.(100 years) ) impact of between 652 and 1,711 average UK citizens.

Cancelling out the Ecopoint environmental impacts of between 608 and 1,600 average UK citizens.

Cancelling out the municipal landfill volume of approximately 150,090 average UK citizens.

Timber-frame semi-detached housing accounted for 2.2% of the new housing starts, and new housing accounted for roughly 30% of all new build and major refurbishment projects. So, if construction clients, policy bodies, planning authorities and development agencies were to ask for good practice on all such projects (i.e. excluding smaller repair and maintenance projects), and if this case study indicated the typical improvement available, the national impact would be more than two orders of magnitude (X100) greater. However, since the case studies show Ecopoint savings ranging from 0.01 to 3.5 Ecopoints per m2 (with timber-frame housing at 0.2 Ecopoints per m2), an accurate assessment of the national impact would require further analysis.


4 Data gaps This report has addressed a new area of investigation by estimating the embodied environmental impacts of increasing recycled content within building projects. It has used a large body of existing data as well as incorporating data that has come on-line during the process of researching the report. Much of the total stock of data used has been collected not specifically for the analysis of this issue; therefore, significant gaps and details peculiar to the use of recycled materials in construction materials have been encountered. Many of these have been resolved, but many have presented practical problems that are not easily overcome. However, the report has begun a new avenue of investigation into the environmental impacts of construction materials in general that is valuable and is likely to receive more attention in the future. In light of this, it is anticipated that the data gaps that have not been addressed will be filled in subsequent reports of this kind. In order to inform the individuals and organisations that will be involved in related future study, the following is a list of data gaps that would benefit from further enquiry and collection of data. The technical and aesthetic performance issues associated with the use of recycled content in the Quick Win categories of this report have not been considered but are recognised, particularly by industry, as being an important aspect of the debate on recycling. Work to look at these issues may add value to this area of study. Also it is universally correct that the more detailed, more accurate and more up-to-date the data available the more accurate and robust the results and the greater the levels of confidence that can be had in them. Therefore, the promotion of a national approach to assist in achieving this end should also be considered. The current revision of BRE’s Green Guide to Specification is already yielding new data that have not been taken into account in this report. Data gaps according to the Quick Win Categories Aggregates

Greater data collection coverage of aggregate-producing plants (primary and recycled) Data collection and measurement for demolition of buildings and planing of roads Data collection on in-situ recycling Separation of the impacts of the different recycling phases (screening, washing etc)

The focus of this study has been on aggregates from CDW. Other lower-volume recycled aggregates are outside the scope of the current study, but could benefit from more detailed study in the future. More detailed research into the use of explosives in UK quarrying would also be valuable. Asphalt

Comparison needed for cold, warm and hot laying of asphalt and the energy consumption of each. Data collection for in-situ recycling and the transport and energy savings this might provide.

Ready mix concrete (RMC)

Incorporation of new data on aggregates Precast concrete paving

Incorporation of new data on aggregates Dense concrete blocks

Incorporation of new data on aggregates Lightweight concrete blocks

Incorporation of new data on aggregates Concrete roof tiles

Incorporation of new data on aggregates In particular, this study found there are insufficient data sets to provide a fair comparison of standard and good practice recycled content for polymer-modified and resin-bonded tiles.


Clay facing bricks Greater data collection coverage of clay brick producing plants Measurement of the different processes and effects of different waste materials on the production

process (energy, water, emissions etc) Plasterboard

Measurement of the impacts of the production of the synthetic gypsum types (energy, water, emissions etc)

Chipboard

Greater data collection coverage of the processing of different wood wastes and the existing infrastructure for wood waste collection

Thermal insulation

Greater data collection on glass wool, cellulose fibre and mineral wool insulation Ceiling tiles

Measurement of the impacts of the production of the synthetic gypsum types (energy, water, emissions etc)

Floor coverings

Greater data coverage of other floor covering types in addition to carpet tiles Drainage products

Data coverage on the production of recycled plastics and their use in drainage pipes that is manufacturer specific, akin the type of data collected in the other categories by BRE to date


5 Conclusion

This report has demonstrated that, for those product categories where sufficient data exist for conclusions to be drawn, on average adopting higher recycled content in a construction project typically reduces overall environmental impacts. Higher recycled content may or may not reduce carbon impacts – the key factor being to ensure that recycled aggregates are sourced more locally than the quarried aggregates they replace. It is also true that higher recycled content does not automatically produce environmental benefits in every situation. In particular, the substantial variation in environmental impact between products at the same level of recycled content means that the trend is not a universal rule – individual products may ‘buck the trend’. It is almost always true that using recycled material reduces landfill and overburden by taking material out of the waste stream and using it, as well as helping to reduce the extraction of primary resources. However, there are cases where a waste material requires more energy to transform it into a useable product than making a product with virgin resources – for example, if a manufacturer uses more cement to incorporate recycled aggregate into a product. The objective of this report, therefore, is to inform policy makers and the construction industry so that they can make educated decisions on the best way of encouraging the use of recycled content in construction projects. Many data gaps and weaknesses have been identified and some assumptions have been made within the different sections of the report, but an attempt has been made to provide an objective appreciation of the relevant issues. Finally the report records the data gaps and assumptions so that future research can improve on the foundations set by the current study.


References i BS (2001). Environmental labels and declarations – Self declared environmental claims (Type II environmental labelling), BS EN ISO 14021:2001, BSI, London. ii WRAP (2004) Making the Case for Quick Win Products in the Construction Sector iii International Standards for the undertaking of Life Cycle Assessment iv Refer to BRE Methodology for Environmental Profiles of Construction Materials, Components and Buildings for further details (ww.bre.co.uk). v Full and confirmed results are available for 2004. vi Highways Agency Specification for Highway Works: Series 600 vii Highways Agency Specification for Highway Works: Series 500 viii Highways Agency Specification for Highway Works: Series 800 ix Lazarus, N, Beddington Zero (Fossil) Energy Development, Construction Materials Report: Toolkit Carbon Neutral Developments – Part 1 x 2003 Report on Waste Arisings by ODPM/CLG xi AMA Research Ltd. (2006). xii AMA Research Ltd. (2006) xiii 0.051 Ecopoints per tonne/km and 4.44 kg CO2 eq.(100 years) per tonne/km (Ecoinvent Database 2006) xiv AMA Research (2006) xv WRAP (2004) Making the Case for Quick Win Products in the Construction Sector xvi BRE have no evidence that this is used within the UK – see “Raw Materials Gypsum in Europe: Potential Usage of Synthetic Gypsum other than FGD Gypsum”, Emmanuale Geeraert and Guido De Lange, Eurogypsum XXII Congress Conference Proceedings, The Hague, May 13-15, 1998, 1 page summary, and 9 page paper, Cited in bibiliography http://www.p2pays.org/ref/02/01827.pdf which states a production of 230k tonnes per annum in Europe. xvii http://www.mtprog.com/ApprovedBriefingNotes/PDF/MTP_BNPB2_2006August9.pdf references to Lafarge Website. xviii Knauf Drywall comment in Choosing construction products: recycled content of mainstream products, WRAP, January 2006. xix http://www.mineralsuk.com/britmin/mpfgypsum.pdf#search=%22synthetic%20gypsum%22 xx http://www.huntsman.com/pigments/Media/Grimsby_2004_Site_Responsible_Care__Report.pdf xxi http://www.npi.gov.au/database/substance-info/profiles/78.html#environmentaleffects xxii In a letter from Liz Parkes of the Environment Agency dated 4 September 2006, to Kieran Miller, Chairman of the Gypsum Products Development Association. xxiii Communication from the Commission of European Communities of Europe to the European Council and the European Parliament on the Interpretative Communication on waste and by-products, Brussels, 21.2.2007, COM(2007) 59 final. xxiv Bonigut, J and Kearley, VC. 2005. Options for increasing the recovery of panelboard waste. WOO0024. ISBN: 1-84405-179-X xxv Hamilton, TE; Alig, JT, and Falk, RH. 1995. Products from Recycled Fibers – A US Perspective. In proceedings of IUFRO XX World Congress "Caring for the Forest: Research in a Changing World", 6-12 August 1995, Tampere, Finland xxvi Personal communication from A Kerr, Director General, WPIF. xxvii AMA Research Ltd. 2006. Choosing construction products: recycled content of mainstream products. xxviii Howard, N.; Edwards, S. and Anderson, J. 1999. BRE methodology for environmental profiles of construction materials, components and buildings. BRE Report BR 370. Garston, BRE. xxix WRAP (2005) Options and risk assessment for treated wood waste states that the British Wood Preserving and Damp-Proofing Association (BWDPA) has concluded that, in the context of the Hazardous Waste List from the EC Hazardous Waste Directive, only Chromated Copper Arsenate (CCA) and creosote timber preservatives are considered hazardous. xxx See http://www.perlite.org/perlite_info/guides/general_info/basic_facts.pdf for further information. xxxi http://www.eurima.org/mineral_wool/composition.html xxxii WRAP (2006) p.1. xxxiii The Guardian (Sept 20th 2004) “The UK’s New Rubbish Dump: China”.

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