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Environmental assessment of external wall cladding
constructionBuket Metin
a& Aslihan Tavil
a
aDepartment of Architecture, Faculty of Architecture, Istanbul Technical University,
Taskisla, Taksim, 34437 Istanbul, Turkey
Published online: 07 Feb 2014.
To cite this article:Buket Metin & Aslihan Tavil (2014) Environmental assessment of external wall cladding construction,
Architectural Science Review, 57:3, 215-226, DOI: 10.1080/00038628.2013.862610
To link to this article: http://dx.doi.org/10.1080/00038628.2013.862610
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Architectural Science Review, 2014
Vol. 57, No. 3, 215226, http://dx.doi.org/10.1080/00038628.2013.862610
Environmental assessment of external wall cladding construction
Buket Metin
and Aslihan TavilDepartment of Architecture, Faculty of Architecture, Istanbul Technical University, Taskisla, Taksim, 34437 Istanbul, Turkey
(Received 8 February 2013; final version received 20 October 2013 )
Decisions made during design, construction and operation phases have effects on the environmental impacts of buildingsthroughout their life cycles. However, environmental impacts of construction process are often ignored. Construction tech-niques affect the overall environmental impacts of construction process by determining the materials, the equipment and thelabour to be utilized for the constructability, which in return affects the amount of energy use and emissions and constructionwastes generated during the construction process. This study proposes a model (environmental assessment of external wallcladding construction, EACC) to assess the effectof external wall cladding construction techniques on environmental impactsduring their construction process. In this context, first- and second-level indicators, environmental impact benchmarks andcontributing factors were defined and scores of the contributing factors were calculated. The pilot study of the EACC sug-gests that construction techniques affect not only resource and energy usage, labour health and safety during the constructionprocess, but also reuse, remanufacturing and recycling possibilities of the materials at the end of their useful life.
Keywords: external wall cladding; construction technique; construction process; environmental impact; environmentalassessment
1. Introduction
The construction industry causes environmental problems
due to its high consumption of the global resources and
its contribution to the environmental pollution through the
building construction and operation activities. According to
Edwards (1999), in the EuropeanUnioncountries, buildings
use 50% of total energy and 40% of raw material, release
50% of chemicalsharmful to the ozone layer, consume 50%
of water and cause 80% of land loss to agriculture fields.
In the Organization for Economic Co-operation and Devel-opment (OECD) area, the building sectors share of total
energy consumption is between 25% and 40% (Ryghaug
and Srensen 2009). Negative effects of buildings on the
natural environment mainly occur during their construc-
tion, as well as their operation and demolition phases.
There are many studies that have explored the relation-
ships between building operation and demolition phases,
and their impacts on the natural environment. However,
there is still a gap in the current body of knowledge about
managing the environmental impacts of construction activ-
ities prior to the construction, and more importantly during
the design phase of a building. This leads to a gap in under-
standing the whole spectrum of the built environment andits potential environmental effects. The interaction between
the building construction process and the environment is
discussed by some studies in certain aspects. Pollo and
Rivotti (2004) focuson buildingsiteand maintenance works
while developing their approach for the optimization of
Corresponding author. Email:buketmetin@itu.edu.tr
design choices from the sustainability evaluation point of
view in the context of the construction process.Shen et al.
(2005)present a computer-based scoring method for the
environmental performance of the contractors during the
construction process. Rivotti (2005) develops a method
that evaluates the eco-compatibility of the technical ele-
ments used for construction activities on-site.Li, Zhu, and
Zhang (2010)develop an integrated life cycle environmen-
tal impact assessment model for construction process to
examine the twoaspects, in terms of the construction equip-ment and the ancillary materials. Gangolells et al. (2011)
propose a method to determine and rank the significance of
defined environmental impacts in a particular construction
project on the basis of their severity and the concerns of
various interested parties.Chen, Okudan, and Riley (2010)
focus on prefabrication and on-site construction methods
in the concrete buildings and investigate the awareness and
environmental concerns of the stakeholders on construction
method selection.
The construction process comprises the initial construc-
tion activities as well as the activities during maintenance,
rehabilitation and renewal processes. Pollo and Rivotti
(2004) indicate that the building process has four mainstages as off-site production, on-site production, use
and maintenance, and demolition and recycling. They
define construction and maintenance stages under on-site
production stage and estimate a buildings impact on the
natural environment during its life cycle approximately as
2014 Taylor & Francis
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216 B. Metin and A. Tavil
being 15% during the construction stage, 15% during the
maintenance stage and 10% during the demolition stage.
Furthermore, assessing the environmental impacts of the
construction process is difficult due to the fact that the
construction process consists of many sub-processes and
there is no recorded data of the comprehensive amounts of
energy use, emissionsand construction wastes (Bilec 2007).
Therefore, assessing the construction process by analysing
different construction techniques at a building element level
would provide opportunities to assess the construction pro-
cess in the context of environmental sustainability within
the life cycle of buildings.
Previous studies approach the construction process in a
holistic view by considering the environmental impacts in
general, but only a few of them investigate the problems
arising from the effect of construction techniques on the
environment. The construction technique itself has several
impacts on the environment by pointing out the inputs of
the construction process as material, equipment and labour,
which increase energy use, emissions and constructionwastes. Consequently, analysing the environmental impact
of the construction process with regard to the construc-
tion technique of a particular building component is also
important from holistic point of view.
External wall and roof systems are the two main ele-
ments of the building envelope. External wall cladding
system design and selection is one of the complicated
stages of the building envelope design, since innovation in
the building material industry and technological develop-
ments has led to a broader range and number of options
for the cladding materials as well as the construction
techniques.
This study introduces a model to be used during thedesign process, which is developed to analyse the external
wall cladding construction techniques, in order to assess
the environmental impacts of the construction processes.
The model aims to assist decision-makers, including but
not limited to the architects, contractors and owners, who
play an important role on many decisions during the design
phase regarding the construction processes. As an initial
step in this study, external wall cladding construction tech-
niques were classified by reviewing the catalogues of the
companies which are external cladding materials and sys-
tem producers in the Turkish construction sector (Metin
2010). Following the initial step, interviews with the exter-
nal wall cladding contractors were carried out in order todefine the environmental sustainability indicators, bench-
marks and contributing factors of the particularconstruction
techniques (Metin 2010). In addition, the score of each con-
tributingfactor of the construction technique was calculated
by using Benefit-Value Analysis (Tapan 1980, 2004), which
usessubjective assessmentand calculates the relative values
of the parameters developed through the assessors experi-
ence. In the end, a pilot study is conducted to demonstrate
the application of the model and to evaluate the results
accordingly.
2. Classification of the external wall cladding
construction techniques
Buildings faces have been changing due to the advances
in building technology and external wall cladding mate-
rials. Every new wall cladding material brings its own
construction technique and each technique may be different
depending on the materials properties such as dimensions,unit weight, connection type and detail design. The term
cladding is often used as a general reference to a wide
variety of naturally occurring and synthetic, or man-made,
building envelope materials, components and systems. In
building terminology, cladding is a non-structural material,
a protective layer or covering that is fixed on the outer
surface of a building or a structure to protect the build-
ing envelope against moisture and foreign elements, and to
provide aesthetic purposes. Often in building construction,
cladding or application of one material over another is done
to complete the cladding as a system. Typically, these ele-
ments are quarried, manufactured or otherwise developed
and/or altered to render them suitable for use on the exter-nal of a building or structure. The essential processes of
wall construction are cutting and assembling, plus form-
casting the cladding material by using ancillary materials
whenever necessary. Those applications have different envi-
ronmental impacts during construction process depending
on the cladding system and its construction technique in
particular.
External wall cladding materials can be assembled on
the building surface/shell by using different construction
techniques. Construction techniques differ according to
dimension, form and unit weight of the cladding material,
type and dimensions of the sub-construction and installa-
tionmaterials, building height, layers of the cladding systemsuch as thermal insulation, waterproofing, sealing, etc. In
the context of this study, cladding construction techniques
are classified according to their installation types as follows
(Table1):
Installing to a sub-construction (metal/wooden
frame etc.)
(1) with screw (Sa)
(2) with special anchorages (Sb)
(3) with standard anchorages (Sc)
(4) by welding (Sd)
(5) with adhesive (Se)
Installing to a wall core (masonry etc.),
(1) with special anchorages (Wa)
(2) with adhesive (Wb)
External wall cladding materials can be assembled on
a metal/wooden frame or metal angle/sheet, which can
be installed to the components of building structural sys-
tem (floors/columns etc.) with screws, special anchorages,
standard anchorages, by welding or with adhesive. These
construction techniques require a wooden/metal frame,
metal angle/sheet for the installation of the cladding and
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Architectural Science Review 217
Table 1. Classification of cladding construction techniques.
Construction technique details
Construction technique Plan Section Elevation
Sa Installing to a sub-construction with screw
Sb Installing to a sub-construction with special anchorages
Sc Installing to a sub-construction with anchorages
Sd Installing to a sub-construction by welding
Se Installing to a sub-construction with adhesive
Wa Installing to a wall core with special anchorages
Wb Installing to a wall core with adhesives
cannot be installed directly on the structural system or core
such as a direct installation on masonry.
Claddings can be assembled on a metal/wooden frame
with screws (Sa) by using three different ways such as con-
cealed screwing, visible screwing or embedded screwing
according to the vision that screws generate on the cladding
surface. Metal and wooden panels, cement-bonded par-
ticleboards and polyvinyl chloride (PVC) panels are the
common types of cladding systems that are assembled by
using this technique.
Claddings can also be mounted on vertical and/or hori-
zontal components by using special anchorages (Sb), which
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218 B. Metin and A. Tavil
are designed and produced by the cladding companies for
the specific cladding component. Sb is applied by using two
different ways. Claddings can be installed with the anchor-
ages fixed on sub-construction. In addition, the anchorages
can be fixed on the sub-construction as well as reverse
side of the cladding and then they are tightened together.
Metal panels, clinker/terracotta tiles, ceramic tiles/panels,
porcelain tiles, marble, granite and PVC panels are
assembled by Sb.
Installing claddings with standard anchorages (Sc) is
especially used for glass fibre-reinforced concrete (GFRC)
panels. Metal angles are fixed on the floors or columns
and GFRC panels are assembled on these angles by using
standard anchorages. GFRC panels produced with special
metal skeleton system can also be mounted to a metal sheet
installed on the floors or columns by welding (Sd).
Claddings can also be installed to a frame with adhe-
sives (Se). A polyurethane-based adhesive is applied to the
reverse side of the cladding and assembled to the frame. Se
is generally used with a metal sub-construction. Woodenpanels and porcelain cladding tiles are generally installed
using this technique.
Wall cladding materials can also be mounted on the
wall core by using special anchorages (Wa) or adhesive
(Wb) without including a sub-construction. The cladding
materials such as granite and marble panels are prepared
with riffles on the upper and lower surfaces for providing
their assembly to the anchorages (Wa). Cement-based adhe-
sives are used for joining the small-sized cladding materials
such as brick veneers on brown-coated masonry (Wb).
Clinker/terracotta tiles, brick veneers, ceramic tiles/panels
and porcelain tiles are assembled by using Wb, while Wa
and Wb can be options for installing marble and granitepanels.
3. Methodology
Environmental assessment of external wall cladding con-
struction (EACC) aims to analyse different cladding con-
struction techniques in design phase to assess and compare
their environmental impacts during construction process.
The model focuses on the construction activities, which
can be realized during construction, use and end-of-life
phases, in order to analyse different construction tech-
niques of external wall claddings. Construction techniques
are analysed regarding their role on resource consump-tion (RC), energy consumption (EC), labour health (LH)
and waste generation (WG) during the construction activ-
ities considering their on-site application features, based
on material/equipment usage, supplementary application
requirements, installation method, labour type/safety and
waste management patterns.
The development of EACC consists of two basic stages:
first the environmental assessment parameters and second
their scores were determined. During the first stage, the
interviews with cladding contractors were conducted and
the data on the construction technique inputs, basically
material, equipment and labour were obtained. Afterwards,
on-site application features of the cladding construction
techniques were defined according to the interviews. Sub-
sequently, the assessment parameters were attributed as
the first- (In) and the second- (Inn) level indicators, envi-
ronmental assessment benchmarks (Bn) and contributing
factors (CFn) in a hierarchical order. Finally, the scores
which are the weights of the contributing factors were
determined to develop EACC, to provide the assessment
and comparison of the cladding construction techniques in
environmental sustainability point of view.
3.1. Identification of environmental assessment
indicators
Gangolells et al. (2011),Chen, Okudan, and Riley (2010),
Bilec (2007)andKim and Rigdon (1998)defined the fac-
tors affecting the environment on the basis of energy, water
and material conservation, emissions to air and wastes.
Construction techniques designate material, equipment and
labour inputs that affect the amount of energy, water and
material used, emissions and wastes created during the
construction process. Thus, previous studies ofPollo and
Rivotti (2004),Shen et al. (2005),Rivotti (2005),Li, Zhu,
and Zhang (2010),Gangolells et al. (2011),Chen, Okudan,
and Riley (2010), Bilec (2007),Kim and Rigdon (1998),
Sev (2008), Peterson and Dorsey (2000), Kibert, Sendzimir,
and Guy (2000, 2002) and Kibert (2007) were reviewed
and the environmental assessment indicators were set in
two levels as first- and second-level indicators in the con-
text of the model according to the data about material,
equipment and labour inputs related to various construc-tion techniques. First-level indicators (In) are designated as
RC,EC,LHandWG. Material,water,electricity and oil use,
site conditions, emission, noise and dust generation, land,
water and air pollution and recovery options are attributed
as second-level indicators (Inn) and they identify in what
waythe first-levelindicators affectthe environment. The on-
site application feature of cladding construction techniques
are designated as the contributing factors (CFn) since each
technique affects the environmental sustainability depend-
ing on its process. Second-level indicators are designated
for each benchmark by considering the contributing fac-
tors. The scores of the contributing factors with regard
to the environmental sustainability benchmarks are allo-cated according to the second-level indicators on which the
calculations are based (Table2).
RC and EC during the construction process should
be controlled in order to reduce environmental impacts.
According to Edwards and Hyett (as cited in Sev 2008),
approximately 50% of all global resources are consumed
by the construction industry. All building activities involve
use, redistribution and concentration of some components
of the earths resources, such as water, energy and materi-
als(Sev 2008). LH is also important during construction
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Architectural Science Review 219
Table 2. Environmental assessment indicators.
First-level Second-level Environmentalindicator indicator assessment(In) (Inn) benchmark (Bn)
I1 RC I11 material use B1 construction typeI12 water use B2 installation method
B3 supplementaryapplications
B4 labour
I2 EC I21 electricity use B3 supplementaryapplications
I22 oil use B4 labourB5 equipment
I3 LH I31 safety precautions B5 equipmentI32 site conditions B6 installation materialI33 emission generation B7 safety managementI34 noise generationI35 dust generation
I4 WG I41 land pollution B6 installation materialI42 water pollution B8 waste management
I43 air pollution B9 reuse possibilityI44 recovery B10 recycling possibilityB11 remanufacturing
possibility
process. Volatile organic compounds (VOCs), dust and
other pollutants produced during the construction process
may be hazardous for labour and public health (Ko and
Alberico, n.d.). Dust generation, which originates from the
construction activities and vehicle emissions, threatens the
health of the laborers. Noise and vibration impacts associ-
ated with the construction activities are also hazardous for
labourers (Ko and Alberico, n.d.).WGduring the construc-
tion process is another environmental problem. Although
quantity and quality of waste generated from any specific
construction project would vary depending on the projects
circumstances and types of materials used, handling of the
wastes should be taken into account carefully (El-Haggar
2007).
3.2. Identification of environmental assessment
benchmarks and contributing factors
Environmental assessment benchmarks (Bn) defines on-site
application features and end-of-life patterns of construc-
tion techniques. During the construction process of externalwall claddings, RC, EC, LH and WG are directly related
to the construction type, installation method and mate-
rials, supplementary applications, labour type and train-
ing, equipment, safety precaution, waste management, and
reuse, recycling and remanufacturing opportunities that are
all benchmarks affecting environmental sustainability. The
contributing factors (CFn) are the options of benchmarks
according to on-site application features and end-of-life
patterns of different construction techniques. The contribut-
ing factors define the environmental impact of construction
techniques according to their relation with second-level
indicators (Table3).
Definition of the benchmarks associated with the con-
tributing factors and their relations with the second-level
indicators are explained as:
Construction type (B1) is related with the com-ponents (building structure/core/sub-construction)
where the cladding is mounted. Claddings can be
mounted on load-bearing building structural ele-
ments such as columns/beams/floors directly or on
a cast-in/masonry/frame wall core without using
any sub-construction or by using a sub-construction
consists of the metal/wooden frame system. The dif-
ference between the components where the cladding
is mounted affects the amount of the material used.
Installation method (B2) is related to the technique,
which is used for assembling the cladding on build-
ing structure, core or sub-construction. Mounting the
cladding with screws/anchorages allows ready-madematerial usage, while bonding agents such as mortar
requires on-site preparation. Therefore, installation
type affects the resource used for the preparation pro-
cess. Screws/anchorages can be used without the
necessity of any extra preparation process; however,
water and energy have to be used for preparing the
binding agents.
Supplementary applications (B3) affect the material
consumption and in case of the necessity of any
extra application such as painting, sealing, etc., the
amountof thematerialused forassembling increases.
Supplementary applications may require energy for
preparation of some components on-site to be usedin bonding and installation.
Labour (B4) is also related to the labour type and
training. Trained labour for a specific construction
technique not only affects the RC, EC and LH, but it
also affects the installation time and the quality of the
entire system. The trained and experienced workers
can provide proper use of resource and energy. More-
over, the same job can be accomplished at a qualified
level in a shorter time compared with an unskilled
labour.
Equipment (B5) used for the assemblage and mate-
rial handling at construction site affects RC and EC
during construction. For instance, certain mechanical
equipments may cause more environmental damages
and emissions due to fuel-oil consumption. Equip-
ment also affects LH due to the high noise levels they
may create.
Installation material (B6) affects the LH directly.
Bonding agents can consist of dust, VOCs and other
chemical components, which might cause hazardous
emissions.
Safety management (B7) is related to the site con-
ditions, which can be hazardous and dangerous for
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220 B. Metin and A. Tavil
Table 3. Environmental assessment of EACC.
First-level Second-level Environmental assessmentindicator (In) indicator (Inn) benchmark (Bn) Contributing factor (CFn) Score
I1 I11,I12 B1 construction type CF1 assembling cladding on building structure 0.51CF2 assembling cladding on a core (cast-
in/masonry/frame)0.26
CF3 assembling cladding on a core usingsub-construction (vertical or horizontal)
0.14
CF4 assembling cladding on a core usingsub-construction (vertical and horizontal)
0.09
I1 I11,I12 B2 installation method CF5 assembling claddings with anchorages 0.52CF6 assembling claddings with bonding agents 0.27CF7 assembling claddings with anchorages and
bonding agents0.21
I1,I2 I11,I12,I21,I22 B3 supplementaryapplications
CF8applying the system without any extraapplication(joint sealant, painting, etc.)
0.83
CF9 applying the system with extra application (jointsealant, painting, etc.)
0.17
I1, I2 I11,I12,I21,I22 B4 labour CF10 assembling claddings by trained labour 0.83CF11 assembling claddings by unskilled labour 0.17
I2,I3 I21,I22,I34 B5 equipment CF12 assembling claddings using hand tools 0.52CF13 assembling claddings using hand tools and
electrical hand tools0.27
CF14 assembling claddings using hand tools,electrical hand tools and heavy equipment
0.21
I3,I4 I33,I35,I41,I42,I43 B6 installation material CF15 causing no emissions and contamination duringapplication (VOC, dust, etc.)
0.83
CF16 causing emissions and contamination duringapplication (VOC, dust, etc.)
0.17
I3 I31,I32 B7 safety management CF17 taking workplace safety precautions 0.83CF18 disregarding workplace safety precautions 0.17
I4 I41,I42,I43,I44 B8 waste management CF19 providing waste management plan 0.83CF20 disregarding waste management plan 0.17
I4 I41,I42,I43,I44 B9 reuse possibility CF21 construction technique is appropriate for
reusability
0.83
CF22 construction technique is inappropriate forreusability
0.17
I4 I41,I42,I43,I44 B10 recyclingpossibility
CF23 construction technique is appropriate forrecycling
0.83
CF24 construction technique is inappropriate forrecycling
0.17
I4 I41,I42,I43,I44 B11 remanufacturingpossibility
CF25 construction technique is appropriate forremanufacturing
0.83
CF26 construction technique is inappropriate forremanufacturing
0.17
labour. Conditions of the construction site affect
the labours health and their performance on-site.Workplace safety precautions have to be taken into
account, planned and controlled carefully.
Waste management (B8) is oneof thesignificant prob-
lems of the construction industry. The construction
industry is facing a challenging problem of look-
ing for landfill sites for construction and demolition
waste (Peng, Scorpio, and Kibert 1997). Therefore,
in the context of the management of the construction
wastes generated during the construction process,
providing a waste management plan should be the
major concern of the decision-makers to decrease the
amount of waste generated on-site. The basic issuesof waste management are developing a site-specific
waste management plan and include it in the contract
documents (Peng, Scorpio, and Kibert 1997). Man-
agement of the construction wastes is related with
managing the works of recycling, remanufacturing
and reusing.
Reuse possibility (B9) is associated with the
reusability capacity of the materials. It is affected
by the construction technique of the external wall
cladding system. As the construction techniques
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Architectural Science Review 221
cause less damage during the construction and demo-
lition phases, the possibility of reusing the materials
and the installation components for another wall
cladding system would increase.
Recycling possibility (B10)isalsoaffectedbythecon-
struction technique and the components of the exter-
nal wallsystem. Thisfactor is directlyassociated with
the recyclability of materials, construction frames
and connectors of lesser quality for either the same
or different purposes by the end of their useful life.
Remanufacturing possibility (B11) is also directly
related to the construction technique. It has the same
purpose with recycling. However, it differs from
recycling, since it means remanufacturing of better
or equal quality and only to be used for the same
function.
3.3. Formulating scores of the contributing factors
The model consists of environmental assessment parame-
ters, which are set up in a hierarchical order. Thus, organi-
zation of the parameters provides using the Benefit-Value
Analysis method for the assessment of the alternatives
(Tapan 1980,2004). The Benefit-Value Analysis is a tool
for preparing decisions systematically, which takes into
account non-quantitative criteria. It uses a multidimen-
sional method to integrate quantitative criteria of many
different perspectives to measure effectiveness and becomes
more distinctive by using various criteria. (Schulze n.d.).
It uses subjective assessment and calculates the relative
values of the parameters developed through the experience
of assessors. Relative values of parameters are calculated
by weighting them according to their relative importance(Tapan 1980). According to Benefit-Value Analysis, rel-
ative values of the alternatives can be calculated by using
different methods such as Von Neumann and Morgenstern
method and Churchman and Ackoff method (Tapan 1980,
2004).
Von Neumann and Morgenstern method is used when
an alternative is preferred to another and the alternatives
can be ranked by the decision-maker (Ackoff, Gupta, and
Minas 1962). This method assumes that the true probabili-
ties are known by the decision-makers and they can identify
their preferences for the possibilities of different combi-
nations(Ackoff, Gupta, and Minas 1962; Fishburn 1964;
Tapan 2004).Churchman and Ackoff method is used for weighting
the sub-goals which have a hierarchical order (Churchman,
Ackoff, and Arnoff 1957; Tapan 1980, 2004). According
to this method, the parameters can be ranked due to their
importance and the numbers are assigned with respect to
their relative evaluation. The method makesno assumptions
about subjective probability or maximization of expected
value. It only resembles a procedure for estimating values
of set of objects where only comparative evaluations are
possible(Ackoff, Gupta, and Minas 1962).
In this study, Churchman and Ackoff method, which
is recommended for determining the weight of sub-goals
and for comparative assessment, is used since the assess-
ment parameters are in a hierarchical order and the
necessity of comparative assessment (Churchman, Ackoff,
and Arnoff 1957;Tapan 1980,2004). Subjective values are
used in developing a quantitative method for the compar-
ison of the construction techniques of the external wall
claddings. Relative values were given to the contributing
factors by taking account of the effect of the second-level
indicators on the particular construction technique. Subse-
quently, scores of the contributing factors, which are the
sub-goals for reaching the minimum environmental impact
during the construction process, are calculated.
The EACC consists of the environmental sustainability
benchmarks having two, three or four contributing factors
(Table 3). Two contributing factors determine a bench-
marks effect on the environment at an extreme level, which
can be either positive or negative. Therefore, they are
regarded as the extreme values. The other contributing fac-tors, which are more than two, affect the environment at
different levels from positive to negative. Consequently, the
calculation of the scores can be derived from two different
modelsas calculation of theextreme values(1) andthe other
values (2).
Extreme values(1):
nCF = 2,
Vmax >Vmin ,
Vmax = 1.00,
Vmin = 0.20.
Other values(2):
2< nCF n,
nCFmax = 4,
V1 > (V2 2) + + (Vn (2n 2)),
Vsn =Vn
V.
The calculation of the scores of the contributing fac-
tors (CFn) for the extreme values requires a definition of
a maximum value (Vmax) and a minimum value (Vmin)
depending on the number of the contributing factors ( nCF
)
(1). According to the Churchman and Ackoff method, Vmax,
which has the most positive effect, has to be maximum 1.00
(Churchman, Ackoff, and Arnoff 1957;Tapan 1980,2004).
The value ofVmin is defined associated with the other val-
ues. The difference between the values (V) of contributing
factors andthe total value of them shouldbe equal in order to
provide the consistency of the benchmarks for the assess-
ment. For this reason, the difference is regarded as 2 and
Vmin is defined as 0.20 in order to point out the extremity
(1). The other values are calculated by comparing thevalues
with each other and the value of CFs are adjusted after each
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222 B. Metin and A. Tavil
comparison (2). Finally, adjusted values are normalized by
dividing with sum of the values (V) and the standardized
values of CFs(Vsn )are calculated (Churchman, Ackoff, and
Arnoff 1957;Tapan 1980,2004).
4. Application of the EACCIn the context of the study, an application is performed to
show the usability of the model. For this purpose, a spe-
cific external wall cladding material was chosen for each of
the construction technique considering the probability of the
installation varietiesof the wallcladdingmaterial during the
construction process. Widely used cladding materials for
the commercial and residential building facades in the Turk-
ish construction sector were selected for the application.
Interviews were conducted with the relevant companies to
collect data forthe assessment of theconstruction process in
particular. Environmental impact of the construction tech-
niques of cladding materials was assessed by using EACC
and results were interpreted according to the features of
each technique. Finally, results were interpreted according
to the first-level indicators, which determine the environ-
mental sustainability of construction techniques during the
construction process.
4.1. Results
The collected data from the interviews were used for EACC
and appropriate contributing factors for each of the bench-
mark were selected from the assessment table for each of
the construction technique. Then the total score of each
first-level indicator was calculated according to the relatedbenchmarks. For example, for a construction technique,
appropriate contributing factors ofB1,B2,B3andB4bench-
marks were selected and sum up to get the RC (I1) EACC
result. Finally, the results are interpreted (Figure 1). The
results of each construction technique are explained below.
Installing to a sub-construction with screw (Sa): Cement-
bonded particleboards are assembled to a vertical metal
sub-construction with screws (Sa) followed by joint sealant
application and painting. Both electrical and hand tools
are used during the process. The cladding company pro-
vides security requirements, but waste management pre-
cautions are not taken into consideration on-site. The Sa
technique for cement-bonded particleboard needs supple-mentary applications which make the recovery options
impossible, since the degrading process during reuse,
remanufacturing and recycling processes is inconvenient.
Therefore, Sa application for cement-bonded particleboard
has a higherscoreof 1.66for RC. ECandLH havethe same
score of 1.27, while the lowest score for WG is calculated
as 0.85 (Figure1).
Installing to a sub-construction with special anchorages
(Sb): Porcelain tiles are mounted to a vertical and horizon-
tal metal sub-construction (Sb), with a special anchorage
type. Both electrical and hand tools are used for the applica-
tion. The cladding company provides security requirements
but waste management precautions are not taken into con-
sideration on-site. Sb does not require any supplementary
application, which makes the recovery options possible and
provides an easier recovery process. According to these
properties, Sb application for porcelain tiles received higher
score of 3.49 for WG. EC and LH yield the same lowest
score of 1.93 and RC has the score of 2.27 (Figure1).
Installing to a sub-construction with standard anchor-
ages (Sc) and installing to a sub-construction by welding
(Sd): GFRC panels can be mounted on the metal sheet,
which is fixed to the columns and floors by using standard
anchorages(Sc) or by welding (Sd).During the construction
process, besides electrical and hand tools, heavy equip-
ments are used for lifting the panels depending on the
size and weight of the panels. The cladding company pro-
vides security requirements but does not take into account
the waste management precautions on-site. Sc technique
requires only joint sealant application, which does not affectthe recovery process directly. Although a different installing
method is needed for installing using standard anchorages
or welding, Sc and Sd techniques for GFRC panels have the
same EACC results because of the similarities in the princi-
ples of the application process. Hence, EC and LH yield the
same and the lowest score of 1.21, while RC has the score
of 2.03 and WG has the highest score of 2.83 (Figure1).
Installing to a sub-construction with adhesive (Se): Lami-
nated wooden panels are assembled to a vertical metal sub-
construction by using polyurethane-based adhesive (Se).
Electrical and basic hand tools are used for this technique.
The cladding company provides security requirements but
waste managementprecautions are not takeninto considera-tion on-site. The Se technique for laminated wooden panels
does not require any supplementary applications, which
make the recovery options possible. Consequently, EC and
LH have the lowest score of 1.93, while RC has the score
of 2.01. WG yields the highest score of 2.83 (Figure 1).
Installing to a wall core with special anchorages (Wa):
Granite panels aremounted to the wall core by using special
anchorages (Wa). The anchorages installed on the wall core
and the granite panels, which are prepared with riffles on
the upper and lower surfaces, are assembled to the anchor-
ages. Electrical and hand tools are used for the technique.
The cladding company provides security requirements, but
waste management precautions are not taken into consid-eration on-site. Wa does not require any supplementary
application, which makes the recovery options possible.
Therefore, EC and LH receive the lowest score of 1.93,
while WG has the highest score of 3.49 and RC has the
score of 2.44 (Figure1).
Installing to a wall core with adhesive (Wb): Granite pan-
els can also be installed on the wall core by using cement-
based adhesive (Wb) and hand tools are used during the
construction process. The cladding company provides secu-
rityrequirements but waste management precautions are not
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Architectural Science Review 223
Figure 1. Assessment of construction techniques.
taken into consideration on-site. Granite panels mounted
with theWb techniquecannot be recoveredbecauseof adhe-
sive usage for installation and joint sealant application. This
situation makes reuse, remanufacturing and recycling pro-
cesses inconvenient for the Wb technique. Hence, RC has
the highest score of 1.53, while WG has the lowest score of
0.85. EC and LH have the same score of 1.52 (Figure 1).
4.2. Discussion
After the assessment of each construction technique, they
were compared with each other according to the first-level
indicators to explore their impact on environmental sus-
tainability. For this purpose, first-level indicator results of
each construction technique were used as the variables for a
statistical analysis, and then means of the first-level indica-
tors were calculated (Figure2). According to the statistical
analysis, the mean of RC, EC, LH and WG indicators were
calculated as 1.996, 1.571, 1.571 and 2.453, respectively.
The means of each indicator were used as the comparison
level and the construction techniques were compared with
each other (Figure3).
I1 Resource consumption: RC indicator has a mean of
1.996(Figure 2). Installing to a sub-construction with screw
(Sa) and installing to a wall core with adhesive (Wb) are
below the mean with 1.66 and 1.53 scores, respectively.
Installing the cladding material to a sub-construction with
special anchorages (Sb), with standard anchorages (Sc), by
welding (Sd), with adhesive (Se) andto thecore with special
anchorages (Wa) areabovethe mean with thescores of 2.27,
2.03, 2.01 and 2.44, respectively (Figure3).
Construction type (B1), installation method (B2), sup-
plementary applications (B3) and labour (B4) benchmarks
affect the results of RC indicator. Wa, which has the highest
score, uses wall core for assemblage without requiring any
sub-construction thus consuming less material during the
assembly. Since only the anchorages are used without the
necessity of any supplementary materials, water and mate-rial consumption is reduced. On the other hand, in spite of
using wall core for the assembly, Wb has the lowest score
for requiringsupplementaryapplications and usingbonding
agents. This causesan increase in itsresource usage. Labour
is directly related to labour training and the trained labourer
usage during the construction process. All the interviewed
companies have labour training programmes which show
positive contributions on the overall results.
I2Energy consumption: EC indicator has a mean of 1.571
(Figure 2). Installing the cladding to a sub-construction
with screw (Sa), with standard anchorages (Sc), by weld-
ing (Sd) and installing to a wall core with adhesive (Wb)
Figure 2. Statistical analysis of results.
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224 B. Metin and A. Tavil
Figure 3. Comparison of construction techniques.
are below the mean with 1.27, 1.21, 1.21 and 1.52 scores,
respectively. Installing to a sub-construction with special
anchorages (Sb), with adhesive (Se) and to wall core with
special anchorages (Wa) are above the mean with a score
of 1.93 (Figure3).
Supplementaryapplications (B3),labour(B4) and equip-
ment (B5) benchmarks affect the results of the EC indicator.
Sc andSd have thelowest scoresfor ECby requiringsupple-
mentary application, such as joint sealant, which causes an
increase in energy use for on-site preparation of installation
materials. During Sc and Sd techniques, heavy equipment
is used because of the GFRC panel dimensions and weight,
which also increases energy use. Sb, Se and Wa have higher
scores for EC by not requiring any supplementary applica-
tion and using hand tools and electrical hand tools which
allow less energy usage during application in comparison
with Sc and Sd techniques. I3 Labour health: LH indicator has a mean of 1.571
(Figure 2). Installing the cladding to a sub-construction
with screw (Sa), with standard anchorages (Sc), by weld-
ing (Sd) and installing to a wall core with adhesive (Wb)
are below the mean with the scores of 1.27, 1.21, 1.21 and
1.52, respectively. Installing to a sub-construction with spe-
cial anchorages (Sb), with adhesive (Se) and installing to a
wall core with special anchorages (Wa) are above the mean
with the score of 1.93 (Figure3).
Equipment (B5), installation material (B6) and safety
management (B7) benchmarks affect results of LH indica-
tor. Sc and Sd techniques have the lowest scores for LH
by requiring heavy equipment usage, which causes higherlevels of noise than any conventional equipment. Sc and
Sd also require joint sealant as supplementary application
that causes dust generation during bonding agent prepara-
tion. Therefore, during Sc and Sd techniques, LH is affected
negatively. Sb, Se and Wa have higher scores for LH by
using hand tools and electrical hand tools for the process,
causing less noise than heavy equipment. Moreover, Se
requires ready-made polyurethane adhesive for the applica-
tionwhichprevents on-site preparation and dust generation.
All the interviewed companies provide safety management
and take workplace safety precautions during the construc-
tion process, which contributes positively to the overall
scores of LH.
I4 Waste generation: WG indicator has a mean of 2.453
(Figure2). Installing to a sub-construction with screw (Sa)
and to wall core with adhesive (Wb) is below the mean
with the score of 0.85. Installing to a sub-construction with
standard anchorages (Sc) by welding (Sd) and with adhe-
sive (Se) are above the mean with the score of 2.83 while
installing to a sub-construction withspecial anchorages(Sb)
and installing to a wall core with special anchorages (Wa)
are above the mean with the score of 3.49 (Figure 3).
Installation material (B6), waste management (B8), reuse
(B9), recycling (B10) and remanufacturing possibilities (B11)
benchmarks affect the results of WG indicator. Sa and Wb
have the lowest scores for WG by requiring supplemen-
tary applications as joint sealant and painting and Wb also
requires a bonding agent for the assemblage. Therefore,
supplementary applications and bonding agent usage make
the degradation process difficult for the future recoveryoptions. Moreover, bonding agent usage causes dust gener-
ation, which can cause land, air and water pollution. Sb and
Wa yield the higher scores for WG by requiring only special
anchorages for the assemblage that prevents bonding agent
usage andmakesrecoveryoptions possible without theneed
for any degradation process. Furthermore, the amount of
dust and emission creation is less in Sb and Wa when they
are compared with Sa and Wb. None of the interviewed
companies provide any waste management plan on-site,
which contributes negatively to the overall results for WG.
5. Conclusions
This research is conducted to investigate the effect of the
construction techniques on environmental sustainability
during the construction process, and the cladding systems
are selected as the focus of this study due to a variety of
construction techniques available for cladding installations.
The EACC results show that RC indicator yields the scores
varying between 1.53 and 2.44 in which installing to a wall
core with adhesive (Wb) has the lowest and installing to
a sub-construction with special anchorages (Sb) has the
highest scores. EC indicator scores vary between 1.21 and
1.93 in which installing to a sub-construction with stan-
dard anchorages (Sc) and installing to a sub-constructionby welding (Sd) have the lowest and installing to a sub-
construction with special anchorages (Sb), installing to a
sub-construction with adhesive (Se) and installing to wall
core with special anchorages (Wa) have the highest scores.
LH indicator gets scores between 1.21 and 1.93 in which
installing to a sub-construction with anchorages (Sc) and
installing to a sub-construction by welding (Sd) have the
lowest and installing to a sub-construction with special
anchorages (Sb), installing to a sub-construction with adhe-
sive (Se) and installing to wall core with special anchorages
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Architectural Science Review 225
(Wa) have the highest scores. WG indicator scores are cal-
culated between 0.85 and 3.49 in which installing to a
sub-construction with screw (Sa) and installing to a wall
core with adhesive (Wb) have the lowest and installing
to a sub-construction with special anchorages (Sb) and
installing to a wall core with special anchorages (Wa) have
the highest scores.
Results of this study demonstrate that the RC indica-
tor is mostly defined by the construction type and by the
supplementary application requirement of the construction
techniques, which affect water and material uses as the
second-level indicators. Results of the EC indicator are
mostly determined by the supplementary application and
the equipment requirement of the construction techniques,
which affect electricity and oil uses as the second-level
indicators. Equipment and installation material require-
ments affect the scores of LH indicator basically with their
influence on the second-level indicators that are emission,
noise and dust generation. When construction techniques
are compared, the biggest differences among the scoresare observed on the WG indicator. Supplementary appli-
cations and bonding agent usage make the recovery options
impossible, since degrading process during reuse, reman-
ufacturing and recycling processes becomes inconvenient.
Moreover, all of the companies, which the interviews were
conducted with, declared that they do not provide any
waste management plan for the construction site during the
construction process. Therefore, these properties cause a
big difference between the construction techniques, which
only include anchorage usage or require bonding agent and
supplementary application usage.
This study shows that the effect of the construction pro-
cess on the environmental sustainability can be assessed byweighting the process of various construction techniques
with the help of comprehensive analysis of the particular
technique. Despite the fact that the construction process
comprises a relatively short time period of the building
life cycle, it affects the environment and human, and its
role on the building life cycle cannot be underestimated.
The EACC method provides assessment and comparison
of external wall cladding construction techniques during
the design process and it helps decision-makers in reduc-
ing environmental impacts of the construction process. The
study also shows that the construction process has negative
effects on environment regarding its various aspects, such
as material and equipment inputs and construction tech-niques, which should not be underestimated to achieve a
holistic environmental sustainability in the building sector.
The EACC method considers only the external wall
cladding construction techniques. The development of
external wall cladding materials and their construc-
tion techniques are in progress and their environmen-
tal impacts of the construction process can be assessed
during the design phase with this method. The method
depends on a subjective assessment methodology; there-
fore, a methodology, which relies on quantitative data
obtained from the stakeholders of the construction indus-
try such as material producers, vendors and constructors
can also be developed. Further research is also needed
to provide a holistic assessment of the construction pro-
cess, which considers other construction techniques used
in buildings. Thus, environmental sustainability of the
construction process can be better assessed and con-
trolled prior to the construction process and during the
design phase.
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