Energy efficiency in the Hellenic building sector: An assessment of the restrictions and...

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Energy Policy 38 (2010) 2776–2784

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Energy Policy

0301-42

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Energy efficiency in the Hellenic building sector: An assessment of therestrictions and perspectives of the market

C. Karkanias a,n, S.N. Boemi b, A.M. Papadopoulos a, T.D. Tsoutsos c,n, A. Karagiannidis a

a Laboratory of Heat Transfer and Environmental Engineering, Department of Mechanical Engineering, Aristotle University Thessaloniki, Box 483, GR 54124 Thessaloniki, Hellasb Department of Environmental and Natural Resources Management, GR 30100 Agrinio, Hellasc Department of Environmental Engineering, Technical University of Crete, Kounoupidiana Campus, GR 19009 Chania, Hellas

a r t i c l e i n f o

Article history:

Received 2 October 2009

Accepted 6 January 2010Available online 12 February 2010

Keywords:

Energy efficiency

Bioclimatic architecture

Sustainable building

15/$ - see front matter & 2010 Elsevier Ltd. A

016/j.enpol.2010.01.009

esponding author.

esponding author. Tel.: +30 2821 37825; fax

ail address: theocharis.tsoutsos@enveng.tuc.g

a b s t r a c t

The significance of bioclimatic architecture has become widely accepted since the 1970s and the

implementation of its principles in practice is a key factor in order to achieve energy efficiency in the

building sector. The way, however, from scientific acceptance to commercial utilization is not a

straightforward one. This paper deals with the notion of bioclimatic architecture in buildings and

investigates the aspects of this concept in Hellas. A sample of university researchers, building

contractors and members of public organisations was interviewed using a standardised set of

guidelines. The barriers to promoting bioclimatic design, role of the local government in the adoption

process, level of environmental culture as well as perspectives of this concept in Hellas were the key

areas of discussion in each of the interviews. The results from the data analysis reveal insufficient

economic incentives, a lack in technical information as well as a lack in specific environmental policies

that would foster the propagation of bioclimatic architecture.

1. Introduction

The economic growth and distribution of wealth producedduring the 20th century has lead to an unprecedented impact onthe environment, with long term reverberations on the biosphereand consequently on the quality of life for human beings(Kennedy, 1993). As a result, the achievement of sustainabledevelopment in order to balance and, if possible, reverse thecurrent trend has become a main target of governments andinternational bodies and organisations. The economic approachtowards sustainable development is based on the relationshipbetween the rates of economic activity and the use of naturalresources. It has become clear that it is necessary for humans touse appropriate technology in a way that will enable the naturalcapacities of ecosystems to generate resource inputs for theeconomy and to assimilate, either by means of absorbing or/andby means of storing without long-term damage, the waste flowsgenerated by the economy (Turner, 1993; Schweizer-Ries, 2008;Tsoutsos et al., 2009).

Nevertheless, since the use of any energy resource has animpact on the environment, the adoption of policies that lead toenergy efficiency through energy conservation is a major tool

ll rights reserved.

: +30 2821 37861.

r (T.D. Tsoutsos).

towards sustainability and also a complementally action to theuse of renewable energy resources. Such policies can be applied toseveral sectors of the economy; the present study focuses on thebuilding sector, which is responsible for about 40% of total energyconsumption worldwide (Wall, 2006).

Ever since the first oil crisis in 1973, it has been realized that alarge percentage of the energy consumed in buildings for theirheating, cooling, and lighting is directly related to the way inwhich the buildings are designed and, particularly, to theirarchitectural features, the properties of the buildings’ elements,and the use of space (Maciel et al., 2007; Isaac and van Vuuren,2009). At the same time, it was also realized that the densely builturban environment creates a microclimate on its own, affectingthe buildings’ energy balance. The theory of the bioclimatic designof buildings, as re-defined by architects in the field of buildingphysics, appears therefore as a logical development and aneffective solution to the problem of energy waste in the buildingsector (Schild et al., 1997). It reduces the energy consumption onthe level of the building as such and at the same time it helps toreduce the urban heat island effect, contributing therefore tosustainability in more ways than one.

This architectural approach improves both energy efficiencyand indoor environmental quality, and consequently thereforealso the quality of life for inhabitants, by exploiting the building’sdesign and structure as such. This is achieved by fitting thebuilding into its physical environment and utilizing local climateconditions, instead of trying to off-set them. In an evolutionary

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process since the early 1970s a series of technologies, which are inthe meantime considered to be ‘green technologies’, have beenembodied in the building’s design, utilizing solar energy, naturalventilation, and the thermal storage properties of both thebuilding’s shell and the ground, in order to achieve lighting,heating, and cooling with a minimum of conventional energyconsumption. These technologies are based on the comprehen-sion and utilization of prevailing climatic conditions, like solarradiation, prevailing winds as well as air temperature andhumidity variations, but also microclimatic conditions, likethe existence of water ponds, the surrounding surface albedo,and the urban heat island effect. Furthermore, they presupposethe exploitation of local topography, including the slope of theground and the site’s orientation and views. Finally, the use oftypical features of local architecture and also of locally usedbuilding materials is endorsed, as those are as a rule betteradapted to the local and regional climatic conditions (Schild et al.,1997; Papadopoulos and Axarli, 1982; Magliocco and Giachetta,1999). In this sense, it is important to mention the way theEuropean legislation defines the concept of bioclimatic architec-ture, namely that: ‘‘it aims at the improvement of the building’senergy efficiency and at the exploitation of renewable energysources by using passive technologies and also by means ofadditional to the envelope active technologies, assimilating at thesame time the building as such into the local physical environ-ment’’ (Directive 2009/28/EC).

According to Edwards (1998), the benefits of bioclimatic orgreen buildings are categorised into direct, indirect, and widerglobal benefits. The direct benefits include lower energy andoperational costs, market advantages for the building developer,higher indoor environmental quality and therefore living qualityor higher productivity the inhabitants and lower long-termexposure to environmental or health endangering factors. Greenbuildings also have indirect benefits and advantages compared toconventional ones: they establish a psychologically and mentallymore pleasant indoor environment, due to the utilization ofnatural lighting and ventilation and, particularly in the case ofoffice buildings, they improve the image of the company. Finally,green buildings have global direct benefits as they can effectivelycontribute to the effort to tackle large scale environmentalproblems such as global warming, loss of biodiversity, ozonelayer depletion, and increasing consumption of resources andmaterials. The risks occurring in the realization of such buildingscan be associated with the reliability of the technology used,increased additional cost, and overall performance of the buildingin daily use.

In this line of thought, the work presented in this paperanalyses the current conditions in Hellas considering thepropagation of bioclimatic architecture and the level of adoptionof this way of design by the local community. After providing abrief review of the current state of affairs, an analysis of datacollected from market players is presented and a section ofrecommendations for national environmental policy making inHellas is discussed.

2. Energy efficiency, environmental performance, andbioclimatic architecture

2.1. Framework in the European Union

In order to promote and support bioclimatic architecture in thebuilding sector, the European Union (EU) has issued directives toenforce the adoption of more environmentally friendly buildingpolicies by its Member States. The most related directive forsustainable building was the 2002/91/EC of the European

Parliament and of the Council of 16 December 2002 on theEnergy Performance of Buildings (EPBD). The transposition datewas in January 2006 with a grace period until January 2009. TheMember States are obliged to apply minimum efficiency require-ments, ensure certification of the buildings’ energy performance,introduce regular inspection of boilers and air-conditioningsystems, and ensure energy upgrading of existing buildings. Inorder to achieve this, the directive foresaw the adoptionof a common methodology for calculating the integrated energyperformance of buildings and also the adoption of minimumstandards on energy performance of both new andexisting buildings.

A further step related to sustainable building was the Directive2006/32/EC on energy end-use efficiency and energy services. Themain aim of this directive is to make the end-use of energy moreeconomic and efficient, by establishing incentives and legalframeworks in order to eliminate market barriers that preventefficient end-use of energy, and to create conditions for thedevelopment and promotion of a market for energy services andfor the delivery of energy-saving programs and other measuresaimed at improving end-use energy efficiency. A major aim of thisdirective is to enhance the formation and operation of ‘energyservice companies’ (ESCOs), which will deliver energy servicesand/or other energy efficiency improvement measures in facilitiesor premises, carrying some degree of the financial risk ofinvestment, as this is seen to be an effective tool to promoteenergy efficiency.

The general target for Member States is to adopt and achievean energy saving target of 9% by 2016, while they also had to setthemselves an intermediate national indicative target to be metby 2009. To promote energy end-use efficiency, Member Statesare asked to develop energy auditing systems for all finalconsumers. Certification following such audits is equivalent tothat foreseen by the 2002/91/EC Directive. The most recent actionof the EU towards sustainable building is the proposal forDirective (COM/2008/0780 final—COD 2008/0223) of the Eur-opean Parliament and of the Council of the energy performance ofbuildings (recast). The aim of the recast of the EPBD is to extendthe scope of the directive and make it more effective by clarifyingcertain provisions; requiring Member States to set up minimumenergy performance requirements when a major renovation is tobe carried out; reinforcing the provisions on energy performancecertificates, inspections, and their respective awarding systems,and finally stimulating Member States to develop frameworks forhigher market uptake of low- or zero-energy and -carbonbuildings. All these have to be supported by encouraging a moreactive involvement of the public sector to provide a leadingexample. The objectives and principles of EPBD are retained whileMember States can determine by themselves their requirementsand ways to implement it. According to the revised EPBD, theminimum total impact of its implementation is expected to be:

emissions in 2020;

construction sector, as well as energy certifiers, auditors, andinspectors of heating and air-conditioning systems.

Apart from the aforementioned directives, which shape theregulatory framework, the European Commission has undertakena series of specific programs and actions to promote thebioclimatic design and use of renewable energies in buildings.The 5th, 6th, and 7th Framework Support Programs (European

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Commission, 2008, 2009) have been examples of such efforts, aswell as SAVE/ALTENER and Intelligent Energy for Europe (I and II).

2.2. Environmental auditing and evaluation

Though not directly part of the move towards bioclimaticbuildings, the environmental auditing and evaluation systems area most useful tool for their propagation. Several environmentalassessment methods exist, which enable the assessment andcertification of buildings. The most popular method in Europe isthe Building Research Establishment’s Environmental AssessmentMethod (BREEAM, 2009), developed in the UK in the 1990s, whichcovers a wide range of building types like dwellings, offices,industrial and retail units, and schools, whilst it addresses a broadspectrum of environmental and sustainability issues. Theseinclude the building’s management, health and well-being, energyuse, accessibility by means of transportation, use of water andresources, waste management, land-use ecology, and pollutionaccording to its performance. BREEAM (2009) uses a straightfor-ward scoring system that has a positive influence on the design,construction, and management of buildings. The levels ofperformance of buildings are divided into: Pass (36 points), Good(48 points), Very Good (60 points), or Excellent (70 points).

The equivalent US system is Leadership in Energy andEnvironmental Design (LEED), which was produced by the USGreen Building Council (USGBC). It certifies sustainable buildingsand is dedicated to expanding green building practices andeducation through its program. It is a voluntary program based onthe participation of various committees’ practitioners. Thesegroups have the opportunity to make comments and review thewhole process. According to Beets et al. (2008), many of the LEEDregistered and certified projects are being initiated using greenguidelines. On the other hand, government agencies and depart-ments offer green building incentives such as tax credits andexpedited permitting when adopting LEED standards.

Apart from BREEAM and LEED there are also Canadian, Korean,and Japanese rating systems such as Green Globes, GB TOOL, andCASBEE, respectively, though they are not frequently used in othercountries (Papadopoulos and Giama, 2009).

3. Sustainability in the Hellenic building sector

Hellas uses mainly oil- and coal-generated electricity to meetits needs for heating, cooling, and lighting in buildings. In1998 natural gas was introduced in the buildings sector andis substituting oil, especially in Thessaloniki and Athens(Papadopoulos et al., 2008). The building sector is responsiblefor about 30% of total national energy consumption and 40% oftotal national emission of carbon (Hellenic Ministry for theEnvironment, Physical Planning and Public Works, 2001; Rapanosand Polemis, 2006). Some interesting data on the building stockare the following: the majority of buildings, namely 77%, areresidential ones, i.e. 71% in cities and 84% in rural areas.The average building’s age is 34 years, i.e. 30.6 in cities and 37.8in rural areas. Commercial buildings account for less than 2% ofthe buildings’ number, but for almost 10% of the building stock’stotal surface. Hotel buildings account for less than 1% of thetotal building stock’s surface; yet they account for 6% of the totalenergy consumption of buildings. Finally, office buildings accountfor some 12% of the building stock’s total surface and for 14% ofthe total energy consumption (National Statistical Agency ofGreece, 2001; Tsoutsos et al., 2008).

The first measure taken in the direction of improving theenergy performance of the Hellenic building stock was theintroduction of the Thermal Insulation Regulation in 1979. It

relied heavily on the German DIN 4108 and was considered to bea tight and effective regulation in those days (Papakostas et al.,2004). However, it has remained unaltered ever since. TheHellenic government, in order to comply with the Europeanguidelines and standards for the building sector, introduced in2001 a law aiming at the reduction of carbon emissions, theadaptation of national standards and the provision of incentivesto improve the energy performance of buildings (HellenicMinistry for the Environment, Physical Planning and PublicWorks, 2001). The law laid emphasis on the establishment oflimits for energy consumption of various building types and alsoon the environmental standardisation of new buildings. It wasaccompanied by an action plan that foresaw incentives forcitizens and companies willing to invest in bioclimatic architec-ture. In that sense, the construction of a bioclimatic buildingwould receive tax exemptions as well as low-interest loans for thepurchase and installation of specific green technologies andmaterials. In addition, there was a series of actions likearchitectural competitions and awards, publication of an energyconservation guide for citizens, information brochures, etc.

The action plan, however, faced a number of obstacles, mainlydue to bureaucratic constraints, which effectively annulated itsimplementation (Staikouras, 2004; Liaropoulos et al., 2008;Spanou, 2008). It was eventually surpassed by the EPBD, whichhad to be incorporated in the national legislation by 2006.Eventually Law 3661/08was published in 2008, which foreseesmeasures to lower the energy consumption in buildings, reconcil-ing with the EU Directive 2002/91/EC. The law includes allrequirements of the 2002/91/EC as well as the adaptation of thenew regulation on energy performance of buildings.

One can therefore deduct that the Hellenic authorities havenever paid close attention on this policy area and that the limitedpropagation of this type of architecture has so far progressedmainly on the basis of individual initiatives. Yet, a few examplesof sustainable building can be found in Hellas. The single mostimportant project was the Solar Village 3, which was built in thelate 1980s in Pefki, a suburb of Athens, as a joint Greek–Germanresearch and demonstration project. All 33 buildings and 420apartments of the Solar Village Project are heavily insulated anduse solar collectors to cover their needs for electricity, spaceheating, cooling, and domestic hot water preparation. Severalstudies have shown that a high thermal comfort in the buildingsduring winter and summer days has been generally achieved. Acharacteristic that keeps the thermal comfort in high level is thehomogenous temperature levels in different rooms and flats allover the buildings. In addition, it was proven that these buildings,due to their high thermal capacity, proper insulation, and cross-sided natural ventilation, did not need air-conditioning systems(Papadopoulos et al., 2008; Tsilingiridis and Sotiropoulos, 1998).

The Solar Sports Hall in Thessaloniki, constructed in 1990, was afurther interesting project, as heating, hot water, and cooling wereprovided without any use of conventional energy, due to the use ofpassive and active solar systems (Papadopoulos et al., 1991).

Then, there is a series of office buildings and private dwellingsdesigned be internationally acclaimed architects like AlexandrosTombazis (Helios 1 and 3, The Wave, AEGEK building, S&Bbuilding, Agrotiki Bank building), Harry Bougadellis (DunantHospital, Panteion University Building, Office Complex Maroussi),Nikos Fintikakis (Thessaloniki Archaeological Museum), YannisKalligeris, and others. Unfortunately, there are almost nopublications in architectural or engineering journals on thesebuildings. Furthermore, most of the aforementioned examples aresingle cases, which resulted from individual initiatives, as a ruleby the wish of the building owner and were supported by actionslike the Green Building Program of the EU or the 3rd CommunitySupport Framework (Karavassili, 2000; Papadopoulos et al., 2008).

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There has been no follow-up to the Solar Village 3 project, norany major initiative by the government or any other public bodyto promote the use of bioclimatic architecture on a broader scale,leading to the necessity to determine the causes for this unsteadyevolution.

4. Methodological approach of the survey

The present analysis is based on a survey that was carried outin spring 2008 in Hellas. The form of the survey was aquestionnaire that consisted of six open–closed questions. TheLaboratory of Heat Transfer and Environmental Engineering hadcarried out a DELPHI study on energy conservation in the builtenvironment in 2007, with 210 persons participating in it. Out ofthose, 82 persons who work on the concept of sustainablebuilding were initially contacted as suitable candidates to narrowthe research in the field of bioclimatic architecture. After a firstround of short interviews, 20 interviewees were selected as themost suitable for the extended interview, which was carried inspring 2008 based on the aforementioned questionnaire. Even-tually, 17 interviews were carried out.

The determination of the sample size was based among otherson the ‘theoretical saturation’ approach (Glaser and Strauss, 1967,Strauss and Corbin, 1998). According to this approach theresearcher continues conducting interviews until data collectionreveals no new data (Douglas, 2003, Goulding, 2002, Locke, 2001).In that sense, the sample size is considered as appropriate andsatisfactory when the data gathered from the interviews becomerepetitive. In this research, the collected data started becomingrepetitive after 15 interviews.

In addition, the determination of the sample’s size dependedon the knowledge on the studied subject gathered through theliterature review. According to Morse (2000), knowledge affectssample size and more specifically the more knowledge exists on asubject area the less sample will have to be adopted. In this case,the extended literature review provided the researcherswith insight and as a result allowed them to guide the interviewsmore efficiently.

Furthermore, the selected interviewees are considered asexperts in the field of bioclimatic design in buildings. Therefore,the expertise in the research area helped in selecting a smallersample size as well as in achieving usable results (Jette et al.,2003). Following this perception, Sandelowski (1995) statesthat ‘numbers are unimportant in ensuring the adequacy of asampling strategy’.

Among the interviewees five were building contractors, sixwere university staff members and researchers, and six weresenior civil servants from related public bodies and organisa-tions. The interviewees were asked to evaluate a number ofcharacteristics related to the diffusion and adoption of biocli-matic architecture (barriers, incentives) and they relied on ascale of 1–5. The scale referred to the importance and dynamicof each of the characteristics. A characteristic evaluated with1 is weak while that evaluated with 5 is very strong. In addition,the interviewees were free, and actually encouraged, toexpress their opinion and make their own comments on theanswers.

The intention of the research was to focus on multiple views ofpeople from different scientific and market areas so as to gatherinformation from several sectors of Hellenic society and toformulate an integrated understanding of bioclimatic architecturein the country. Therefore, the interviewees were divided intothree categories: building contractors, university researchers, andmembers of public organisations.

Building contractors were chosen in order to investigate theproblems faced by these market players in real life, whenattempting to promote this alternative type of architecture. Ascontractors are those directly in contact with prospective buyers,they are ultimately responsible for the implementation ofsuch projects.

The second category, namely university researchers, waschosen in order to identify all the aspects of sustainable buildingand find out what can be done to make this notion widelyaccepted within the engineers, the constructors, the society and,eventually, the state. University researchers can ideally be theones who are able to provide specific examples of effectivepromotion and successful implementation of bioclimaticarchitecture from all over the world and hence enhance itssocietal visibility.

Finally, public organisations could provide information on howthe Hellenic state could help, by providing incentives to thecontractors and the public in order to invest in sustainablebuilding. In addition, public organisations were chosen so as toidentify the level at which they could assist in promotingthis concept.

5. Results and analysis

The survey’s questions were related to the concept ofsustainable design in buildings and the existing barriers to itspromotion in the Hellenic building sector. The goal was to identifythe perception of how the Hellenic state has embodied in itsnational legal framework the recent European directives, as wellas of the knowledge on measures taken by the government andthe local authorities to support and enhance bioclimatic archi-tecture. Furthermore, interviewees were asked about the attitudethe market has to adopt in order to promote this mode of design.They were also asked to review the provision of economicincentives and to assess the future of bioclimatic architecture inHellas.

5.1. Barriers for promoting sustainable building

The answers to this question varied depending on theinterviewees’ categories. With regard to the barriers for promot-ing and implementing bioclimatic design in Hellenic buildings,both building contractors focused on economic factors and theshortage of information. On the other hand, the universityresearchers and the civil servants agreed by large that eventhough economic factors are very serious barriers, other factors,such as the absence of environmental awareness and the lack oftechnical knowledge, are also very important (Fig. 1).

The general attitude of contractors is that the main barrier foradopting bioclimatic architecture is the higher total cost of thebuilding due to the use of more expensive building materials andthe installation of passive energy systems. The prevailingconsideration was that, the higher the construction cost thesmaller the selling profit; therefore their attitude was negative. Asone of the university researchers stated, the economic advantagefor the contractors is that the profit from designing andconstructing a conventional building is more quickly achievableand reaches up to 160% of the construction cost, while the profitfrom bioclimatic buildings is much smaller. In this way, theproportion of customers who want to invest in such buildings issmaller than those choosing to buy conventional ones. As can beseen in Fig. 1, 10 interviewees believe that high construction costis an important (or very important) obstacle for adoptingbioclimatic design in buildings, while 14 among them indicatethe absence of economic incentives as the main barrier.

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Fig. 1. Barriers in promoting bioclimatic architecture.

The rest of the interviewees believe that, apart from economicproblems, there are other major barriers for the adoption ofsustainable building. One of them has been the absence of urbanand land planning during the last 30 years in Hellas. As a result,the vast majority of new buildings have been constructed in avery dense and clustered urban space. This configuration does notfavour the implementation of bioclimatic architecture, as there isa lack of wide streets, big sites, and exposed facades, limitingtherefore the utilization of the sun. The 1960s and 1970s werecharacterised by the domination of tall buildings, with very fewfeatures of traditional Hellenic architecture. These verticalbuildings with narrow vents along the floors and without anythermal insulation in their walls and roofs generated seriousoperational problems such as insufficient lighting and poorventilation, besides their very high energy consumption and theresulting operational expenses (Papadopoulos et al., 2002;Sardianou, 2007; Seyfang, 2009).

The deficiency in technical expertise of this ‘new’ way ofbuilding by civil engineers, as well as the absence of architectsfrom the construction process, has been and remains anotherbarrier. Even in certain cases where engineers and architects triedto apply bioclimatic design, they did so in a rather unsuccessfulway. Some of the interviewees stated that there was little or nointegrated cooperation among architects, civil engineers, andmechanical engineers, a situation that has inhibited the wholedesign and construction process.

The vast majority of the interviewees consider one of the mainbarriers to be the lack of an environmental consciousness,awareness, and culture in Hellas. The Hellenic society is notappropriately aware of issues related to the environment ingeneral and thus to the specific issue of sustainable building. Asmost of them stated, more than two thirds of the population doesnot believe that their buildings are responsible for environmentaldegradation. Moreover, governments have not focused on provid-ing people with information about this significant issue. Inaddition, they have not given incentives to the public to investin sustainable buildings. The fact that a separate Ministry ofEnvironment did not exist in Hellas until October 2009, under-lines the absence of focused and dedicated environmentalplanning by the state.

5.2. National regulations

The second matter subject to discussion was the extent towhich the Hellenic state has embodied relevant Europeandirectives in national regulations aiming at the energy efficiencyof buildings. All interviewees answered that national regulationhas embodied all the aspects of the European directives, thoughhalf of them argued that while the Hellenic state has madesignificant progress, a number of changes have to be made for thenational regulation to be fully reconciled with what takesplace in practice.

University researchers and civil servants reacted positively tothe enforcement of national regulation by the national govern-ment, in terms of Law 3661/2008. However, they all argued thatthe real issue determining the legislative measures’ efficacy willbe the adoption and implementation of standards, guidelines, andcalculations’ procedures, as the European directive leaves to eachMember States the initiative to elaborate and apply those, withregard to local conditions.

A further point raised was the necessity for the Hellenic stateto persist and overview the implementation of the standards inpractice and not rely solely on the contractors’ consciousness and/or good intentions to do so. Furthermore, the notion of bioclimaticdesign in buildings must be clarified by details and characteristicsof the minimum energy and environmental performance that abuilding has to achieve, in order to be classified as bioclimatic.

More particularly, the Hellenic state must establish a mechan-ism to audit and verify certain levels of performance both in thedesign and in the construction phase. According to manyinterviewees, it will be necessary to check if a building thatreceives certification for its energy performance fulfils all relevantrequirements after the construction has been accomplished, aprocess not carried out until now. In order to do that, pubicauthorities must be reorganised so that they can carry out theinspections needed, or assign the audits to private auditors andverify the overall process. The latter is not a preferable solutionamong the interviewees, as can be seen at Fig. 2, despite the factthat it is the solution foreseen by the EPBD and Law 3661/2008.This attitude indicates the lack of confidence in the function ofauditors who are not civil servants. Almost all the participants

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Fig. 2. Measures for national regulation to reconcile with the European Directive.

agreed that a targeted plan by the state to invest in the vocationaltraining of engineers as auditors could be a very effective measurein this direction.

5.3. Measures to promote bioclimatic design in buildings

The role of the state and the provision of economic incentivesto promote bioclimatic architecture constitute the two subareasof the third question. The answers to this issue diverged. Morethan half of the interviewees argued that authorities, either thegovernment or local authorities, should provide economicincentives to citizens and contractors, while the rest of themeither disagree with this policy or suggest that economicincentives have to be indirect.

In terms of the role of the state, a big part of the intervieweesargue that it should let the market operate freely and make onlydiscreet interferences. In contrast, university researchers believethat the government should introduce a general plan for themarket’s operation and carry out regular inspections to controlthe application of the legislation.

According to the building contractors, interference by thegovernment to date has created problems and malfunctions in themarket. The enforcement of a national regulation would be a veryeffective step in this direction only if the government let themarket act freely, without any interference by the state and on itsown initiative. Building contractors also expressed the opinionthat the state should assist them by providing economicincentives and particularly by taking over a proportion ofthe additional cost arising due to the incorporation ofbioclimatic features.

On the other hand, some of the interviewees did not believethat a provision of economic incentives by the state to theconsumers so that they can invest in sustainable building isfeasible. According to them, what is needed is for the governmentto act in two directions, in order to achieve a tangible result.Firstly, the General Building Regulation has to be modified toprovide architects with more flexibility to act, since they are theexperts in building design and the assignment of projects to civilengineers has delayed the propagation of bioclimatic architecture.Secondly, the procedure of issuing building permits must besimplified, as it is actually a time-consuming process, which also

raises construction costs significantly. The state should provideeconomic incentives only in the case of renovation of existingbuildings, particularly in areas where socioeconomically weakparts of the population live. The role of the state could, andshould, be expanded in other areas, such as supporting continualvocational training of architects and engineers, and also of thecraftsmen and technicians who are involved in the constructionprocess.

A part of the interviewees agree with the provision of indirecteconomic incentives. As they stated, funding a percentage of theadditional cost is not the priority, as the prospective buyer canappreciate that this amount will on the long run be paid back bythe lower operational cost of the bioclimatic building. What theHellenic state should do is to lower the fiscal value of property, i.e.the state-defined value according to which the building is taxed asa property. Further lowering the taxation and VAT rates formaterials, systems, and equipment used for bioclimatic applica-tions should be considered. Finally the need for the authorities tofocus on the cultivation of environmental consciousness in Hellasand on the provision of information to citizens was approved bythe vast majority of the interviewees (Fig. 3).

In terms of the provision of just or fair economic incentives,answers varied. Almost half of the interviewees believe that theadoption of this measure is sufficient in order to make this type ofarchitecture attractive to investors. Yet, the rest of the partici-pants either argue that this measure is not the main priority forthe government, or that other additional measures are moresuitable for this action (Fig. 4). In this sense, the governmentshould provide technical information to investors so that they canbe aware of the advantages of bioclimatic design in buildings. Thisapproach is based on the perception that the only way in whichconsumers can be attracted and convinced to invest in suchtechnologies is to be informed and persuaded of the benefits ofhighly energy efficient buildings, with much lower energyconsumption than in the conventional ones and, consequently,reduced annual operational costs.

5.4. Perspectives for bioclimatic buildings in Hellas

The last subject of discussion was the foreseeable future ofbioclimatic design in the Hellenic building market. Considering

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Fig. 3. Measures for promoting bioclimatic architectures.

Fig. 4. Direct economic incentives.

Fig. 5. Perspectives of sustainable building in Hellas.

the current conditions and initiatives only one out of fourinterviewees answered that this type of architecture will play amajor role in the building sector in the future. Yet, even so, thereare several preconditions to be met, and therefore a series of

measures to be implemented, if this approach has to besuccessful. On the other hand, the majority of the intervieweesare not optimistic about the adoption of bioclimatic design inbuildings in the future (Fig. 5). The latter result underlines the

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existence of several obstacles and difficulties in overcomingthem, when moving towards the application of bioclimaticarchitecture in practice. It is believed that the absence of strictlyenforced environmental policies, as well as of environmentalculture on the level of the local society, is and will remain animpediment against the spread of this notion in Hellas in theforeseeable future.

6. Conclusions

The development of bioclimatic architecture in Greece hasbeen rather disappointing so far, being limited to some veryinteresting public pilot projects and to some very interesting, butnot representative, private buildings. Typical, average residentialor mixed use buildings are still lagging far behind the energyperformance standards met in other European countries. Theresearch carried out showed that all factors of the market agree atleast in the determination of the main reasons for this unhappystate of affairs.

The analysis of the interviews reveals a relative unanimitybetween university researchers and senior civil servants inseveral of the discussion areas dealt in the questionnaire. Incontrast, in most areas the representatives of the buildingcontractors group articulated a different approach to several ofthe issues. The interviewees of the first two groups seemed tobe aware of most, if not all, of the aspects defining the conceptand the implementation of bioclimatic design in buildings. Thework carried out by university researchers and the experienceof the senior members of public bodies and organisations hasgiven them a more comprehensive view of the problems relatedto bioclimatic architecture in Hellas. It has to be noted thatmost of their answers were linked to two specific problems, i.e.the lack of information and knowledge, and the lack ofeconomic incentives.

In terms of barriers for the promotion of sustainable buildingin Hellas, beyond the shortage of economic incentives andtechnical expertise, there are other important ones such as lackof urban and spatial planning during the last 30 years, lack oftechnical knowledge by investors, and lack of environmentalculture and consciousness, as well as absence of adequateenvironmental policy by the state, both the central governmentand local authorities.

Considering the government’s initiatives, all of the intervie-wees agreed that the Hellenic state has finally incorporated therelevant European directive in the national regulation. Yet, thereare several more steps to be made, before the regulation can besuccessfully implemented and these include the elaboration ofguidelines and standards, as well as the establishment of amechanism of audits and inspections.

The provision of economic incentives and the role of the statewere the topics with the most divergent answers. Less than half ofthe interviewees believe that the state should provide economicincentives to investors, while the rest did not endorse this policy,indicating the need for other indirect incentives. Finally, in termsof the future propagation of bioclimatic design in buildings inHellas the majority of the interviewees were not optimistic. Asmost of them indicated, there are several major obstacles to beovercome, which prevent a faster and more effective propagationof bioclimatic architecture in the Hellenic building sector.However, as could also be seen, there were signs of a change ofattitude and perception, both by the state and the public, and thisis probably the most important single reason for a carefullycontained optimism.

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Waste Management & Research

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DOI: 10.1177/0734242X10375867

published online 14 July 2010Waste Manag ResSN Boemi, AM Papadopoulos, A Karagiannidis and S Kontogianni

practices in GreeceBarriers on the propagation of renewable energy sources and sustainable solid waste management

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Research Paper

Barriers on the propagation ofrenewable energy sources andsustainable solid waste managementpractices in Greece

SN Boemi, AM Papadopoulos, A Karagiannidis and S Kontogianni

AbstractRenewable energy sources (RES), excluding large hydroelectric plants, currently produce 4.21% of total electricity production

in Greece. Even when considering the additional production from large hydroelectric plants, which accounts for some 7.8%,

the distance to be covered towards the objective of 20% electricity produced from RES by 2010 and respectively towards 20%

of total energy production by 2020 is discouraging. The potential, however, does exist; unfortunately so do serious barriers.

On the other hand, solid waste management (SWM) is an issue that generates continuously increasing interest due to the extra

amounts of solid waste generated; the lack of existing disposal facilities with adequate infrastructure and integrated man-

agement plans, also often accompanied by legislative and institutional gaps. However, socio-economic and public awareness

problems are still met in the planning and implementation of RES and SWM projects, together with the lack of a complete

national cadastre and a spatial development master plan, specifying areas eligible for RES and SWM development. Specific

barriers occur for individual RES and the on-going inclusion of waste-derived renewable energy in the examined palette

further increases the complexity of the entire issue. The consolidated study of this broad set of barriers was a main task of the

present study which was carried out within the frame of a Hellenic–Canadian research project; the main results will be

discussed herein.

KeywordsBarriers, energy policies, legislation, renewable energy sources, waste management

Date received: 4 January 2010; accepted: 23 May 2010

Introduction

Since the 1990s the demand for a change in energy policies

has become a major issue globally, driven by a complex set of

economic, environmental, security and social concerns.

Political and legislative changes that have occurred have

had a profound influence on the development of renewable

energy systems (RES) either directly or indirectly. On a

European level, changes have been expressed in a series of

Directives dealing with renewable energy matters, including

the Directive on the promotion of electricity from RES

(EC, 2001b) and the Directive on the promotion of biofuels

(EC, 2003b) which aimed at the elimination of existing bar-

riers. Within this process, new policies are being elaborated

after the adoption of the climate change and energy package

proposed by the Commission in January 2008. In this line of

approach Directive 2009/28/EC of the European Parliament

and of the Council of the 23rd April 2009 repeals Directives

2001/77/EC (EC, 2001a) and 2003/30/EC (EC, 2003a).

That is a far-reaching package of proposals that falls

within the line of the EU’s ambitious commitment to fight

climate change and promote renewable energy up to 2020

and beyond. The recently proposed EU policy on the pro-

motion of renewable energy, therefore, leaves it to up to the

Laboratory of Heat Transfer and Environmental Engineering,Department of Mechanical Engineering, School of Engineering,Aristotle University of Thessaloniki, Thessaloniki, Greece.

Corresponding author: S. N. Boemi, Laboratory of Heat Transfer andEnvironmental Engineering, Department of Mechanical Engineering,School of Engineering, Aristotle University of Thessaloniki, 54124Thessaloniki, Greece.Email: boemi@aix.meng.auth.gr

Waste Management & Research

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Waste Manag Res OnlineFirst, published on July 14, 2010 as doi:10.1177/0734242X10375867

member states to decide how to split their national target

between the heat and the electricity sector (Klessmann 2009).

The share of RES in primary energy consumption in the

27 EU member countries increased from 4.4% in 1990 to

6.7% in 2005; this development led to a respective reduction

in CO2 emissions (Eurostat 2006). However, increasing over-

all energy consumption in absolute terms has counteracted

some of the environmental benefits from the increased use of

RES (Toke 2008). The strongest increase came from wind

and solar energy, with biomass playing a significant role

more recently. Despite the progress made, significant

growth is needed if the indicative target of 12% for the

EU, referring to primary energy consumption, is to be met

by the end of 2010 (Figure 1) (Skoulaxinou et al., 2006).

In order to reach this target an increase in the share

of RES-based electricity from 13 to 21% is needed.

On the other hand, solid waste management (SWM) is

another important issue. EU directives and national legisla-

tion are forcing governmental and private organizations to

undertake measures in order to improve the current state of

affairs in the SWM field. The legislation aims at sustainable

SWM, according to valid international standards and calls

for a direct application of national laws and their continuous

update in order to include all waste categories. Similarly, an

important step towards the achievement of sustainability is

the operational optimization of existing projects and the

implementation of those already scheduled. This implies

the necessity for planning all the required installations and

ensuring their cost-efficient and cost-effective operation.

In Greece, until the late 1980s, solid waste was buried in

sanitary landfills but also, and frequently so, in open

dumps. That was partly due to the absence of organized

facilities and authorized landfill sites, as well as the often

poorly drafted administrative procedures. Greek national

targets, as set by legislation and environmental planning,

include the implementation of internal SWM systems in all

prefectures throughout the country, the progressive minimi-

zation of biodegradable municipal waste which are currently

leading to landfilling, the progressive increase of recycling/

reuse of packing and other products waste, the existence of

sanitary landfills in all prefectures and the operational con-

trol of open dumps and their progressive closure as soon as

all the currently planned SWM projects have been imple-

mented (Xirogiannopoulou 2007; Boemi et al., 2009).

The Greek situation

Even though a major part of the Greek mainland and also

many Greek islands have a high RES potential and despite

the significant technological advances of the last decade,

which in theory allows even up to 100%RES supply in isolated

areas, the actual use of RES is still rather limited. Between 2004

and 2008, electricity generation from RES increased by 21.1%,

whereas electricity consumption as such grew by 4.21% (RAE

2008). In line with earlier estimates, Greece predicts that elec-

tricity generation from RES will increase, but with less than

10%of the effort made towards the target, it is unlikely that the

initial target for 2010 will be achieved (Figure 2).

RES-E 2006 breakdown

Biogas Solid biomass

Biowaste Geothermal electricity

Photovoltaics

Wind on-shore Wind off-shore

Hydro small-scale Hydro large-scale

AT BE CY CZ DE DK EE ES FI FR GR HU IE IT LT LU LV MT NL PL PT RO SE SI SK UK

Figure 1. Renewable electricity generation in European Union in 2006. Source: Eurostat/Fraunhofer ISI: Electricity fromrenewable energy sources 2006 breakdown of normalized renewable electricity in 2006.

2 Waste Management & Research 0(0)

A series of European Directives were integrated into the

national legislation, in order to create a framework that will

guarantee rapid progress in the development of RES. These

include (a) Directive 2009/28/EC, which establishes a

common framework for the promotion of RES-based

energy; sets mandatory national targets for the overall

share in gross final consumption of energy as well as the

share of energy from RES in transport; and lays down

rules relating to statistical transfers between member states,

joint projects between member states and with third coun-

tries, guarantees of origin, administrative procedures, infor-

mation and training, and access to the electricity grid for

energy from renewable sources; and finally, establishes sus-

tainability criteria for biofuels and bioliquids; (b) the

Directive 2001/77/EC (EC, 2001a), which requires that elec-

tricity from RES has guaranteed access to the grid and

requires member states to set rules for sharing and bearing

the cost of various grid investments necessary to integrate it;

(c) COM (2006)848 [Communication from the Commission

to the Council and the European Parliament: renewable

energy roadmap: renewable energies in the 21st century:

building a more sustainable future. http://eur-lex.europa.eu/

LexUriServ/site/en/com/2006/com2006_0848en01.pdf] which

noted that grid connections and extensions needed to be sim-

plified and stated; and (d) SEC(2008)57 [Commission Staff

Working Document: the support of electricity from renewable

energy sources. Accompanying document to the proposal for

a Directive to the European Parliament and to the Council on

the promotion of the use of electricity from renewable energy

sources (COM (2008) 19) http://ec.europa.eu/energy/clima-

te_actions/doc/2008_res_working_document_en.pdf], which

noted that despite the requirements of Directive 2001/77/EC,

project developers still faced different grid-related barriers

that were mainly related to insufficient grid capacity,

non-transparent procedures for grid connection, high

connection costs and long lead times to obtain authorization

for grid connection. The communication noted that high pri-

ority should be given to removing administrative barriers and

improving grid connection for RES.

Greek legislation incorporated the aforementioned direc-

tives in a series of successive laws, the last one being Law 3468/

2006 on ‘Production of Electrical Energy from RES and com-

bined heat and power in the gross electricity production and

other’. The law simplifies licensing procedures, and it provides

a feed-in tariff guarantee for 10 years, which can be extended

by 10 years following a producer’s unilateral declaration

towards the transmission system operator. That was made

in order to expand the electrical power market and to provide

long-term stability. This 20-year period is one element of best

practice for national support schemes, because it provides the

stability and support of long-term mechanisms.

Furthermore, a series of supplementary laws and minis-

terial decisions were passed into law to create the framework

for an efficient implementation of the system. In some

instances they have been used in conjunction with green cer-

tificate/obligations support schemes. In most cases they are

used by electricity suppliers to show their consumers that

they have purchased ‘green electricity’ but many of the

barriers in promoting RES still remain.

Still, and despite considerable effort, one of the major

barriers is the overall authorization procedure and grid con-

nection. As depicted in Figure 3, Greece ranks in the last

third of the average lead time for overall licensing procedures

in Europe.

The main problem associated with SWM until 2000 was

the disposal of waste at illegal dumps, which in some cases is

still performed now. The number of illegal dumps has been

reduced from 5500 in the early 1990s to 500 at the present

day. For its municipal solid wastes, Greece today (i.e. end of

2009) has over 50 sanitary landfills in existence (with roughly

Lignite

2006 2007 2008

Natural gas

Hydroelectric

Natural gas

Imports

Lignite

Figure 2. Greek Electric Energy Balance for Continental and non- interconnected islands [The energy produced in the non-interconnected islands accounts for some 9% of the total annual production (3.9 TMh oil and 447 GWh RES). The total power ofPV is around 23.278.] Source: Data by RAE, 30/09/08, processed by the authors.

Boemi et al. 3

50 others in various planning, permitting and construction

stages), five mechanical–biological treatment facilities

(with roughly 15 others planned), as well as numerous trans-

fer stations, 23 material recovery facilities for packaging

waste, three facilities for waste from electric and electronic

equipment (WEEE) and other facilities for specific fractions.

Still greater effort is urgently needed on waste prevention,

management of the biodegradable fraction and hazardous

waste, as well as proper operation of existing facilities.

Until the late 1990s all generated waste were landfilled

(cf. Figure 4); however, this picture has actually changed in

the last decade as recycling rates have risen due to the con-

struction of several alternative treatment sites and the

promotion of source separation.

In working towards the achievement of the recycling and

reusing goals set by the EU, the Hellenic authorities have

instituted certain measures and actions for the promotion

of a national strategy (Theochari et al., 2006); eventual over-

all minimization of waste by the year 2010 at a level of 20%

lower than the waste generation of 2000. From 2010 and

until 2050 the goal is set at minimization of 50%, regarding

the waste which is disposed of in landfills, and additional

priority is given to the minimization of hazardous waste.

For the assistance of regional agencies and competent

SWM authorities in the future planning of SWM, the devel-

opment of supporting studies was organized within the frame

of the Operational Program ‘Environment’ of the 3rd

Community Frame of Support (CFS), whereas after 2008,

SWM (as well as waste-water management) projects are to

be financed from 4th CFS funding resources.

Barriers to the propagation of RES and SWMprojects in Greece

Considering Greek morphology, climate and economic

development, it becomes evident that it is a clustered coun-

try, which incorporates mountainous areas and islands, high-

income tourist regions and low-income rural areas, as well as

highly urbanized cities and sparsely populated remote areas.

Despite this fact, a series of studies have proved that there are

several drivers and barriers that are common for the whole

country. Administrative and procedural decoupling of con-

flicting interests characterizes most of the identified barriers.

In particular, Eurostat (2007) used socio-economic indicators

in order to categorize the RES barriers in Greece.

Table 1 summarizes the drivers and barriers for RES and

SWM projects in Greece; barriers that apply at the national

level will be mentioned in the following subsections herein.

Technological barriers

Different needs emerge for the use of RES in the interconnected

mainland and for their use in the islands, with their non-inter-

connected electrical system. As can be easily deducted, when it

comes to the needs of themainland, the transmission network is

muchmore suitable to absorb the electrical energy produced by

RES in areas with increased potential and enable its transmis-

sion to the urban areas where most of the demand is located

(Tsoutsos et al., 2004). The insular electrical grid connections

are rather weak and unsuited to absorb the power produced by

wind farms (Oikonomou et al., 2009).

Austri

Belgium

Bulgar

Irelan

Poland

Slovak

Sweden UK

Lead time for overall procedure

Lead time for grid connection

Biogas

Biomas

Tide &

Figure 3. Average lead time for overall authorisation procedure and grid connection. Source: ‘Promotion and growth ofrenewable energy sources and systems’ COM 2009.

Concerning the exploitation of wind energy,

Papadopoulos et al. (2007) have presented the currently lim-

ited capabilities of absorbing RES-generated power.

The need of upgrading existing grids is a time-consuming

and expensive procedure, especially in the case of high-vol-

tage nets. These problems occur mainly in the regions

of Thrace, Evoia and Lakonia, where there is a high invest-

ment interest due to the very favourable wind potential.

The seasonal fluctuation of the energy demand, especially

on Greek islands, underlines the weakness of the network’s

infrastructure. There is an absence of balance between the

demand and the offer of energy. In particular, when referring

to the use of RES, usually photovoltaic (PV), at a site

the lack of knowledge not only to the know-how but also

experience in installing such kind of systems is often

observed.

20071995

Slovak

iaSlov

Poland

Irelan

United

Estonia

Finlan

lyEU-2

Austri

iumSwed

Figure 4. Percentage of municipal waste that is landfilled in the EU-27, 1995 and 2007. Source: Eurostat (2009).

Table 1. Barriers for RES projects in Greece

Barriers Renewable Energy Systemsa Solid Waste Managementb

Technological Lack of trained human resources. Immature Technology.

EnvironmentalIncorporation costs for RES. Small capacity – Lack of sufficient

waste quantities.High cost of grid connection.

Social and political There is no maturity to the recognitionand realistic assessment of the RES potentialand performance.

Lack of trained human resources.

EconomicLack of funds. Luck of funds – grants.

Participation in EU funding projects inpublic-private partnerships.

Cost barrier (in terms of fee gate).

Legislative and administrative

Delays to overall procedure. Unstable legislation framework.

Lack of special spatial design for RES. Luck of strategic plan.

Ineffective control mechanisms andadministrative structures.

Source: aDEPOIR (2007) and bpartly based on Skoulaxinou et al. (2006).

Boemi et al. 5

Technological barriers exist in the SWM field in terms of

which technology should be chosen and who should apply it

since there is alack of experience in this technology. SWM

technology is not yet mature in Greece and copying solutions

from other European countries is not the ideal solution.

Decisions should instead be based on understanding the tech-

nical and physical resources in order to deal with the SWM

problem. An important issue is the need for technology

transaction and not technology transfer. For this reason

careful consideration of certain requirements concerning

the location where the project will be implemented is

required.

Environmental barriers

Amajor problem with the Greek energy market, at least in its

current shape, is that environmental costs are not adequately

internalized. While the production of fossil energy is com-

bined with the greenhouse gas emissions, and consequently

with global warming, the costs of these external factors are

poorly reflected in the energy market price. Fortunately the

external environmental costs are only reflected in the eco-

system to a small extent (Stangeland, 2007).

According to Oikonomou et al. (2009), the effects on

environmental barriers can be recognized on the ecosystems,

on the landscape and on the change of land use. More ana-

lytically, fauna and flora can change until a RES project is

completed. In particular, minimal interventions should be

made in order for the site to be restored to its original

environmental state as soon as possible upon completion of

the work.

SWM effectiveness and sustainability depends on devel-

oping the capacity of the local authorities to manage natural

resources and using appropriate means to prevent and con-

trol any environmental concern. There are cases in which a

SWM facility proved environmentally unfriendly since the

treatment residues were disposed of either onto land or

water. Therefore a strategic plan which will include proper

solutions for all kind of solid waste as well as treatment res-

idues is more than necessary in Greece.

Social and political barriers

Social and political barriers usually interact with each other;

when governmental and/or local authorities are reluctant to

make decisions and, through lack of knowledge, they fail to

properly inform citizens on the necessity (or not necessity) of

planned projects. The later leads to inaccurate opinions

expressed by others, which are usually then adopted by

citizens.

Social barrier is often the most important and critical

factor because it refers to the public acceptance of the

RES. An important number of complaints end up published

in the local press and on the internet. Insufficient sources of

information are used in order to inform and guide the public.

There is a failure in the market to estimate the impact of

RES, especially wind farms, considering the financial and

social benefits at the local community level, such as the cre-

ation of new jobs, whereas in some cases, as in the islands,

wind farms can also be used as tourist attractions, destina-

tions for educational excursions, etc. (Tsoutsos, 2001;

Papadopoulos et al., 2007).

Construction and design standards do not include PV

installations or use of geothermal energy which will help to

the expansion of RES systems to the local market and to the

conscience of the consumer. Around the world and in

Greece, there are a variety of construction- and operation-

related standards that include RES applications. These do

not work properly and are not focused on ensuring that con-

tractors will have the necessary experience and knowledge

regarding RES.

For a long period, the Hellenic government was reluctant

to make decisions on the construction of SWM facilities. The

main reason was the high financial and political cost, as well

as the pertinent lack of any kind of related motivation or

awareness. Furthermore, Greece lost the opportunity to uti-

lize substantial funds for integrated SWM interventions

during the 3rd Community Support Framework, as with

only one exception (that of the Chania Mechanical

Biological Treatment plant), only new landfills and transfer

stations were built, whereas more than 300millionE were

spent between 2000 and 2006 in order to create a total landfill

capacityof around 2.5million t year�1.

During past years SWM was the exclusive domain of local

authorities, which eventually grouped into larger SWM

authorities but recently government have moved to put in

place the existing spectrum of environmental law and regu-

lations. As a result, there is a growing dynamic and a pressing

need for effective co-ordination among all levels of govern-

ment as well as between public, private and social actors, in

order to resolve political conflict over allocation of the

increased cost of SWM (Macdonald and Vopni, 1994). The

lack of appropriate know-how and flexibility in local author-

ities often leads to unavoidable delays. When combined with

bureaucratic procedures this leads to huge project delays and

sometimes into stopping the operation of the facility.

Furthermore, the lack of environmental education in the

community leads to unfavourable reaction to the construc-

tion of an SWM plant and when the latter is combined with

contradictory political interests the procedure may present

serious delays.

There is an imperative need for the modernization of

SWM authorities’ legal status and improvement of their

human resources in order to be able to (Karagiannidis

et al., 2008):

. apply cost-efficient gate fees

. develop long and medium term business plans

. participate successfully in EU-funded projects

. collaborate with other local authorities

. participate in public-private partnerships.

Economic barriers

There is an absence of economic advantages and motivations

for implementing RES systems in buildings. Moreover the

initial cost is still high both for commercial and domestic

use. Only a small effort has been made over the last term

from the Greek market to reduce the price of PV but the

overall investment still remains expensive and with a 7-year

amortization period.

The currently valid Law 3468/06, which was introduced in

June 2006, aimed at simplifying and speeding up the whole

procedure but without result as yet. Even though quite a

large number of investors have expressed interest in RES

projects, the results have remained meagre (DEPOIR,

2007). Even in situations in which feed-in tariffs were

almost too attractive, as in the case of photovoltaics, prog-

ress has been slow and tedious (Papadopoulos and Karteris,

2009).

Most of the citizens and SWM authorities in Greece are

still ‘used’ in very low gate fees for the provided SWM ser-

vices, in the range of 8–35E tonne�1 of waste. This fee range

does not even cover the typical minimum needs for a good

landfill operation, monitoring and aftercare. With the excep-

tion of the region of Attica and Thessaloniki, solid waste

generation rates in the rest of the country require the instal-

lation of small-capacity waste treatment units which raise the

total specific cost of construction and operation (and thus the

gate fee) by discouraging scale economics. As a result, there

is need for cooperation between local authorities and prefec-

tures for the planning, construction and operation of decen-

tralized SWM plants, in addition to the two major

metropolitan areas of Athens and Thessaloniki in which

large-size facilities are built as well as planned.

Legislative and administrative and barriers

Some governmental procurement policies have been devel-

oped, aiming at the promotion of sustainable commercial

development of renewable energy but the still prevailing inef-

ficient bureaucracy continues to create major obstacles

(Tsoutsos, 2001).

There is a rather complicated licensing procedure for RES.

For example, ten (10) essential documents are needed in order

to start the installation of a PV system on a building andmuch

more in the field (Figure 5). Concerning the construction of a

wind farm, the duration of the entire procedure is more exten-

sive (Figure 6). The whole duration for a PV park is about 2

years, whereas for a wind farm it can reach 4 years.

The lack of a national spatial master plan for RES is

another barrier. In 2007, the RES-specific spatial plan was

published, but its implementation has shown that there are

many questions to be answered, before it can actually help to

speed up the whole procedure.

Finally, a problem that cannot be left unaddressed

concerns the fact that the same projects are simultaneously

monitored concerning their operation and performance by

different authorities. The turn-key cost of wind farms is mon-

itored by the Ministry of Development, which grants the

production licences and is also responsible for managing

the European Union funds in the energy sector. The monthly

and annual energy output is monitored by the Hellenic

Transmission System Operator (HTSO), which is responsible

for the payment of energy producers. The Regulatory

Authority of Energy monitors the producers’ compliance

with the terms of the production licences, as well as the

evolution of the electricity market as a whole. Although

both HTSO and RAE are supervised by the Ministry of

Development, this fragmentation does not enable a rundown

of the data needed for the evaluation of the energy perfor-

mance and economic efficiency of wind farms (Papadopoulos

et al., 2007). Finally, the Ministry for Finance is monitoring

the cash flows from national funding sources.

Maximum time

Minimum time20

0Stage 1 Stage 2 Stage 3

Figure 5. Stages of development and operation of a PV park.Source: DEPOIR, (2007).

50 Maximum time

Minimum time

0Stage 1 Stage 2 Stage 3

Figure 6. Stages of development and operation of a windfarm. Source: DEPOIR (2007).

Boemi et al. 7

The necessity of a strategic plan is more pressing now

than ever in the field of SWM project implementation,

while the establishment and application of rules and meth-

odologies for control and monitoring is a strict requirement

to secure proper operations and funding as well; the organi-

zation, consolidation and reliable concretization of consis-

tent SWM policies is hence the only way to go (Ministry of

Economy and Finance, 2006). All aforementioned positions

have to be part of, but also result from, legislation and a

management structure which should at last ensure that all

procedures in the life-cycle of SWM projects run in an effi-

cient and transparent way. A serious problem is that in

Greece there is still a lack of compliance control mechanisms

as well as major capacity and institutional gaps. This situa-

tion has resulted partly from a past but still partly prevailing

attitude of regarding SWM legislation more as a wish and

less as an obligation. To change this there is a need to both

modify administrative structures and to put in place effective

control mechanisms among all levels of government, as well

as raise awareness and build capacities at all levels and in a

continuous way.

RES potentials in Greece by improved/changed waste management according toEU directives

Although Greece will meet its climate change targets under

the Kyoto protocol, progress is slow in the areas of nature

and biodiversity protection and in waste management.

Greece will need to make further efforts to complete its

planned programmes on sewage waste treatment and on clos-

ing and restoring illegal landfills.

According to Stachowitz (2003) electricity may be gener-

ated from landfill gas (LFG) of 35% methane content per

volume and above. SCS engineers prefer a more practical

approach suggesting that small landfills (less than 0.5mil-

lion tons) and old landfills generally cannot support

LFG-to-energy projects. Medium-sized landfills (0.5–3.0mil-

lion t) are capable of supporting projects only in the 500 to

2000 kW range (Tsatsarelis et al., 2006). On the other hand,

energy LFG projects will assist to the achievement of the

Kyoto protocol targets but also to raise the percentage of

RES use.

From a technical point of view, the utilization of landfill

gas can be achieved for even small landfills; for example, for

a Hellenic city of 30 000–40 000 people, which produces

around 10 000 tMSWyear�1. If this amount of waste is land-

filled for more than 8 years, it will eventually produce

140m3LFGh�1, and this would satisfy the lower limit of

feed for a 250 kW internal combustion engine. However, it

was calculated that such an investment would not lead to

a profit, as the equivalent cost for construction and operation

of this facility was only marginally lower than the profit from

selling the produced electricity. On the other hand, for a

larger sanitary landfill which received for example, more

than 100 000 tMSWyear�1, a LFG-to-energy facility of

1MW could be sustained. It has been estimated that such a

facility would be profitable after about 10 years of operation

and this is obviously among the main reasons and drivers for

the existing facilities at Ano Liossia (13.9MWe) and

Tagarades (5MWe).

The methane contained in the LFG which is to be gener-

ated from new Hellenic landfills is generally able to sustain

LFG-to-energy systems, even if the objectives of the landfill

directive (setting limits to the amount of biodegradable and

packaging materials to be deposited in landfills) are strictly

achieved within the allotted timescale. This result is mainly

justified by the fact that landfills are still the prevailing option

in Hellenic solid waste management in the majority of its

prefectures and it appears that this situation will not radically

change in the following years.

The assumed recycling of landfilled paper and composting

of food waste in the landfill directive scenario has led to

a foreseen reduction of degradable deposited waste and,

therefore, maximum methane production was nearly 60%

lower than that in the do-nothing scenario according to

EC/1999/31 (Tsatsarelis et al., 2009). Figure 7 illustrates

the calculated overall production of methane for the period

1960–2028 from Hellenic landfills. Official national estimates

for the period 1990–2005 are also included (Tsatsarelis et al.,

2006).

It can be observed that current calculations and official

estimates are similar for the period 2000–2005, but there is a

difference of 12–16% for the years 1990–1999. This difference

may be justified by the fact that the older official calculations

were made using a zero-order model, which is considered to

produce less reliable results. Although the landfill directive

scenario is considered to be the closest to the foreseen future

reality, deviations may occur from the prescribed goals.

Currently in Greece, 18.9MWe are generated from

LFG-to-energy systems. Recently landfill operators in

Greece seem to be generally in favour of LFG-to-energy

projects, as currently (2008), the price of electricity produced

by LFG is set at 75.82EMWhe�1 and regulated as an alter-

native energy source. Many sanitary landfill operators in

Greece who were interviewed concerning the options of

biogas recovery indicated that they were unwilling to go

into early gas collection and treatment from the first

months of landfill operation, which although partly

understandable from a financial standpoint is surely not

acceptable environmentally or even under certain health

and safety considerations (Tsatsarelis and Karagiannidis

2009). The early installation of the growing internal combus-

tion engine (ICE)-electricity pair is not necessary (especially

since it is coupled with high investment costs, in the range of

3 to 4MEMWe�1) but the early installation and operation

of the capture network may be combined with other

aforementioned techniques for poor LFG-treatment at the

early landfill stages; in this context, horizontal collection

pipelines, which have already been installed in various new

Hellenic sanitary landfills, show some advantages over the

traditional vertical wells in terms of early installation poten-

tial, since vertical wells can only be operated after the final

landfill height has been reached.

Additionally Hellenic landfills have a key role in the

future which includes LFG upgrading for injection into the

natural gas network, as well as ‘weak’ gas management by a

variety of techniques including aeration, biofiltering, flaring

and fluidized bed combustion.

Conclusions

Price-setting policies in order to reduce cost and pricing-

related barriers will give a boost to the development of

RES. Furthermore, proper education of the local communi-

ties will help in overcoming the social reaction.

Government should facilitate RES’ purchasing in early

market stages with a view to overcoming the institutional

barriers to commercialization, to encourage the development

of appropriate infrastructure and to provide the local mar-

kets with paths for technologies that require integrated tech-

nical, infrastructure and regulatory changes.

Even though public support for renewable energy and

sustainable SWM practices has expanded rapidly in the

past decade, a wide variety of policies have still to be

designed and implemented in order to promote further devel-

opment in these two side-by-side fields. With regard to RES,

a clear increase in the amount of Megawatts produced from

RES is needed via more effective measures in order for

Greece to achieve the 20–20–20 target by the year 2020.

A new legislative framework on RES launched in Greece

on December 2009 during the preparation of the present

paper clearly points to this direction.

Concerning SWM, landfilling, problems and space limita-

tions are also drivers towards waste-to-energy, because the

reduction of waste going to landfill may become the major

issue after some years when all newly constructed landfills

reach their designated capacities. However, waste-to-energy

should be seen as a competitor to landfilling and in the con-

text of integrated SWM by first promoting prevention and

recycling under a life-cycle approach. On a local level, it

seems that the cost barrier is the biggest problem, as well

as a lack of grant funding. Small capacity is also a problem

in most of the regions of the country, requiring tailored and

customized solutions.

The common factor influencing both RES and SWM is

that a significant effort has to be made in order to achieve

durable success in the field of investments. This applies to

the measures that have to be taken and implemented by the

Hellenic government in order to reach the aforementioned

targets that have been set, and to those that apply to the

administrative level, which lies within the responsibility of

regional and local authorities, in order to streamline the

procedures. The experiences of countries that are more

advanced in the specific fields have shown that a mature

technology and an appealing programme of subsidies are

prerequisites, but are not necessarily enough to advance

the market by themselves. In that sense, and despite the

difficulties discussed herein, the growing environmental

awareness of citizens and the ambitious political aims may

lead to the desired positive results faster than has been

expected.

r–1)

01960 1970 1980 1990 2000 2010 2020 2030

Official estimations

Do nothing scenario

Landfill directive scenario

2040 2050 2060 2070 2080 2090 2100

Figure 7. Calculated annual methane generation from Hellenic sanitary landfills and the semi-controlled landfills of Shisto,Ano Liossia and Tagarades. Source: Tsatsarelis et al. (2009).

Boemi et al. 9

Acknowledgements

The authors wish to acknowledge the General Secretariat forResearch and Technology and also the Hellenic Ministry of

National Education and Religious Affairs for partly fundingthis research within the frame of a nationally funded bilateralresearch project between Greece and Canada identified by the

acronym DEPOIR (contract No.9387/05).

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International Journal of Ventilation ISSN 1473-3315 Volume 10 No2 September 2011 ________________________________________________________________________________________________________________________

________________________________________________________________________________________________________________________

A Statistical Approach to the Prediction of the

Energy Performance of Hotel Stock

S.N. Boemi1, Τ. Slini2, A.M. Papadopoulos2 and Y. Mihalakakou1

1Department of Environment and Natural Resources Management, University of Ioannina, 30100 Agrinion, Greece

2Laboratory of Heat Transfer and Environmental Engineering, Department of Mechanical Engineering, School of Engineering, Aristotle University Thessaloniki, 54124 Thessaloniki, Greece

Abstract The issue of evaluating possible strategies for improving the building stock’s energy and environmental performance is crucial. This applies to all buildings including residential and non-residential. In particular, hotels represent a group of both economic importance and public interest. Within the frame of a field study, and in a bottom-up approach, data related to the energy and environmental performance of Hellenic hotels were gathered, along with information related to occupancy levels, indoor environmental quality matters and management procedures. At the same time, and in a top-down approach, data were obtained from the Hellenic Tourism Organization and the national and regional Hotel Chambers. These data provide a reliable background in order to elaborate statistical indices, such as the mean, mode and median for the energy performance of various hotel groups. The idea of a “typical” hotel, as well as its respective performance, remains, however, vague and has to be linked to the aforementioned bottom-up approach. The present analysis is an attempt to group the main features via descriptive statistics and identify possible associations and correlations between energy figure factors. Key words: hotels, top-down approach, bottom-up approach, energy performance, Greece. 1. Introduction Ever since the oil crisis in 1973, it has been realized that a large percentage of energy consumed in buildings for their ventilation, heating, cooling, and lighting is related directly to the way in which the buildings are designed (Maciel et al., 2007; Isaac and Van Vuuren, 2009; Karkanias et al., 2010). At the same time, it was also realized that the densely built urban environment creates a microclimate on its own, affecting energy balance. An architectural approach improves both energy efficiency and indoor environmental quality, and consequently the quality of life of the inhabitants, by exploiting the building’s design and structure (Karkanias et al., 2010). In an evolutionary process, since the early 1970s, a series of technologies, which are collectively known as “green” technologies, have been embodied in building design. This utilizes solar energy, the natural building’s shell and the ground, in order to achieve lighting, heating, and cooling with minimum conventional energy consumption (Papadopoulos, 2007). In this sense, it is of interest

to notice the way in which European legislation defines the concept of bioclimatic architecture. Despite these efforts existing experience shows that, in order to support energy saving in the tourism sector, isolated promotional activities are not sufficient (Karagiorgas e al., 2007). Hence, the whole tourism industry’s features should be studied. In this paper a combination of bottom-up and top-down modelling approaches is presented in order to describe the above features and to determine Hellenic hotel types, with a view to producing a viable strategic plan for improving the energy and environmental performance of hotels. 2. European Union and Hellenic Legislative Framework In order to promote and support energy conservation in the building sector, the European Union (EU) has issued Directives to enforce more environmentally friendly building policies to be adopted by its Member States. The most relevant Directive for sustainable building is the 2002/91/EC directive of

SN Boemi, Τ Slini, AM Papadopoulos and Y Mihalakakou ________________________________________________________________________________________________________________________

________________________________________________________________________________________________________________________

the European Parliament and of the Council of 16 December 2002 on the Energy Performance of Buildings (EPBD) and its follow up, the 2010/31/EC (EPBD recast), which was adopted on 19 May 2010. A further step related to sustainable building was the Directive 2006/32/EC on energy-use efficiency and energy services. The main aim is to make the end-use of energy more economic and efficient, by establishing incentives and legal frameworks that encourage efficient end-use of energy, and create conditions for the development and promotion of a market for energy services. The general target for the EU is to adopt and achieve an energy saving target of 9% by 2016. Moreover, according to Directive 2002/91/EC, Member States were forced to develop and implement energy auditing systems applying to the building stock and ensuring transparency in the energy performance of buildings for the final consumers, in order to promote energy end-use. The most recent action of the EU towards sustainability in the building sector is the Directive COM/2008/0780 final – COD 2008/0223. This revision of the EPBD clarifies certain provisions particularly relating to: minimum energy performance requirements, certification and inspections. It also develops a framework for higher market uptake of low- or zero-energy and carbon buildings. Member States should apply a methodology, at national or regional level, of building energy performance calculations on the basis of the general framework (Article 3). On this legal base, the EPBD Directive has been harmonized in the Hellenic legislation, with the Law 3661 “Measures for the reduction of energy consumption in buildings” (Official Journal of the Government of the Hellenic Republic, FEK 89/19 May 2008) and the Regulation of Buildings Energy Performance (KENAK). This framework forms the basis for regular audits, the determination of requirements for heating, cooling, air conditioning and lighting and building performance in general. However, there is still a gap of expertise considering the implementation of the regulation, particularly in complex, public use buildings, such as hotels. 3. The Hellenic Hotel Sector Tourism is among the most dynamic branches within the services sector of the Hellenic economy. According to the most recent statistical survey, the Hellenic hotel industry follows a steady trend,

presenting a rise in annual turnover of about 5.8% for 2006, which corresponded to a rise from 2.54 bn € in 2005 to 2.69 bn € (Hellastat, 2009). This figure represents 15% of the Hellenic Gross Domestic Product (GDP), underlining the role of the branch as an essential development tool for the national economy. During the following years, despite the worldwide economic crisis, tourism in Greece is expected to develop with an annual growth rate of 6-7% (ITEP, 2009). The fact that there are more than 9,000 hotels in the country, with 693,252 rooms in operation, demonstrates the importance of the branch also for the regional development of the country (NTO, 2009). As Greece is on the way to transform itself to an upmarket tourism destination, the need for an increase in high quality, resort accommodation becomes apparent. On a national policy level this high quality tourism infrastructure development has been identified as a priority target and the creation of integrated resorts, which offer a wide variety of touristic services is encouraged. In the last decade, this led to an overconcentration in four main areas. Therefore, a strategic plan for spatial development has been in consultation in order to achieve a balanced touristic growth. Furthermore, and aiming at the improvement of the existing infrastructure, the lengthening of the operational season (Figure 1) and the improvement of alternative forms of tourism, combined with a series of structural, financial and administrative measures were adopted by the State. With respect to the sustainability, the measures are based on the EU’s encouragement towards improving the environmental performance of services and products. Also, in order to improve the energy performance of the tourism sector, one cannot fail to underline the role of voluntary environmental quality labelling schemes such as Eco-label and ISO 14001. Within the tourism sector, hotel enterprises are the major energy consumer. Surveys conducted by the Center of Renewable Energy Sources (CRES) have shown that although hotels represent only 0.82% of the building stock, they consume 10% of the total primary energy consumption, with an average specific annual consumption of 407 kWh/m2. If energy demand is analyzed with respect to its time variation, it is obvious that the peak values are recorded in the summer season, due to the use of air-conditioning for space cooling, a fact that is

________________________________________________________________________________________________________________________

reinforced by the seasonal character of Hellenic tourism (Figure 1). An in depth investigation on the current state of energy use in the sector is presented aiming to highlight the potential and the importance of a master plan for the implementation of an energy renovation strategy. The purpose is to lead the hotel industry on a sustainable touristic development road by improving the quality of its facilities and its services. Within the scope of this paper, a comparison of bottom-up building physics stock models is provided in order to analyze the hotel sector energy outputs and inputs. Based on this analysis, conclusions can be drawn about energy use in the hotel sector, by using a top-down analysis. 4. Top-down and Bottom-up Modelling Approaches The methodologies and the underlying techniques available for modelling in the hotel sector and, generally, in the building sector have been a topic of discussion in a plethora of articles (Koopmans et al., 2001; Tuladhar et al., 2009; Vuuren et al., 2009; Kavgic et al., 2010). Two fundamental classes of modelling (outlined below) are usually used to predict and analyze various aspects of the overall building stock energy use performance. 4.1. Bottom-up Approach Bottom-up models have been widely used within energy analysis and planning. Models of this type are fully detailed and describe a number of specific

energy technologies with both technical and economic parameters. Both present and future technologies are often included, which means that these models include a description of the change in parameters e.g. fuel substitution options based on knowledge of the stage of development of new technologies (Kavgic et al., 2010). Models based on the bottom-up approach can be either optimisation or simulation models. Additionally, bottom-up models include energy demand, divided into end use demands (e.g. heating, lighting, ventilation, process) rather than divided into energy sources. The latter reflects the view that developments in energy demand tend to depend more on the different purposes for which energy is used, than on the specific energy source and the characteristics related to this source including the energy price. Bottom-up models of hotel energy demand are typically based on vintage models of a large number of end use technologies (Jacobsen, 1998). 4.2. Top-down Approach The top-down modelling approach works at an aggregated level. Econometric top-down models are primarily based on energy use in relationship to variables such as the existence of air-conditioning systems, restaurants, pool, seasonality etc. A top-down method implies that energy demand is determined by relative prices, income or production and exogenous energy efficiency. This energy efficiency is quantified from bottom-up calculations that are aggregated to the level of the macroeconomic model (Jacobsen, 1998).

Figure 1. Complement of the Hellenic tourist sector (ESYE, 2007).

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4.3. Model Comparison A simple comparison between those models can lead to quite diverse results. The difference between the approaches and the consequences for costs has been treated in depth (Jacobsen, 1998; Kavgic et al., 2010; Tuladhar et al., 2009). As argued by Hourcade and Robinson (1996), both top-down and bottom-up models can be optimistic or pessimistic on costs. Bottom-up models tend to be optimistic on the technical cost, while top-down models are often more negative on this issue. Top-down models can be either optimistic or pessimistic, regarding the existence of double dividends. The effect of double dividend in a top-down model could produce costs that are negative and in this way the top-down model could be more optimistic than some bottom-up models. The relative advantages of the two approaches for analyses in different fields could be summarised at the Table 1. 5. Bottom-up Approach The hotel distribution across Greece is studied by means of 3 independent parameters: the climatic zone, the region (official administrative division) and the geographic area of the country. The data are supplied through the Hellenic Chamber of Hotels, concerning the year 2009 and were processed using MS Excel and SPSS 17 software. By using the data provided by means of the top-down approach to obtain the necessary background on the hotel buildings’ features, the bottom-up approach will be used to provide the necessary insight to the buildings’ energy performance and its impact on the feasibility and viability of energy conservation measures in the branch. The results of the bottom-up analysis showed that almost half of the hotels (49%) are located in

climate zone A, characterized by mild, sunny weather conditions and high temperatures throughout the year. On the other hand only 2% are in zone D. Respectively, the region of South Aegean accommodates 20% of the hotels, followed by Crete (16%) and Central Macedonia (12%). At the same time, 40% of the Hellenic hotels are situated in the Aegean islands and Crete, while the geographic area of Macedonia hosts 16%. Both the region and area of Thrace has the minority of hotel infrastructure. These results are depicted in Figure 2. In an effort to study and quantify the relation between the hotels’ location and the 3 aforementioned division types, the non parametric Spearman correlation coefficient was estimated for the available data. It is proven that the hotel site is strongly correlated to the climatic zone (R2=99%, statistical significance at the 0.01 level), though there is no statistical significant correlation between the site and either the region (R2=13%), or the geographic area (R2=44%). Furthermore, a linear regression model was fitted in order to examine and express the relation of the hotel frequency and the allocation. The hotel distribution may be successfully expressed by the parameter of the climatic zone (coefficient of determination r2=98%), but it is poorly expressed by the geographical area (coefficient of determination r2=19%). The linear regression models fit is depicted in Figure 3. Hence, the evaluation of the results suggest a considerable association between the development of lodging infrastructure and the climate conditions. Meanwhile the impact of division using administrative criteria is proven insignificant to hotel allocation. Moreover, in another effort to identify the relation between hotel rating and variables (such as the hotel size, the number of rooms and beds, the climate zone etc.), the Spearman correlation coefficient was

Table 1. Advantages of bottom-up and top-down modelling approaches (Jacobsen, 1998).

Bottom-up Top-down regulation and detailed energy planning; restructuring of energy supply sector; using standards for housing insulation or electric

appliances; and project the technological development in order to

quantify the aggregated development in energy efficiency.

energy taxes; effect of different economic scenarios on energy and

environment; macroeconomic consequences of changes in the

energy system; and general equilibrium effects.

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Peloponnisos Epirus

Northern Aegean

CreteCentral Greece

Ionian Islands

South Aegean

ThessaliaWestern Greece

Western Macedonia

Central Macedonia

East Macedonia & ThraceAttiki

Peloponnisos Epirus

Northern Aegean

CreteCentral Greece

Ionian Islands

South Aegean

ThessaliaWestern Greece

Western Macedonia

Central Macedonia

East Macedonia & ThraceAttiki

Ionian Islands

Central Greece

Peloponnisos

Dodekanese & Cyclades

Epirus Thessalia

Thrace

Macedonia

Ionian Islands

Central Greece

Peloponnisos

Dodekanese & Cyclades

Epirus Thessalia

Thrace

Macedonia

Figure 2. The hotel distribution according to (a) climatic zone, (b) region and (c) geographic area.

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calculated. At the same time, a linear regression was implemented in order to express the rating as a function of the aforementioned dependent variables. The results showed weak linear correlation between the hotel rating and the other variables under study (ranging between -0.27% and 45%), while the linear regression resulted in a poor model (coefficient of determination r2 ~ 30%). Considering the above outcomes, there was an attempt to use the hotel size instead of hotel rating. The Hellenic hotel law, as expressed by the presidential decree 43/2002, divides hotels into small, medium and large according to the number of beds: 1-100 beds are small hotels, 101-300 beds are medium hotels and 301 upwards are large hotels. According to the Spearman correlation coefficient the hotel size seems highly correlated to the same set of variables (correlation coefficient ranging between 0.87% - 85%) and can be satisfactorily expressed as a function of the number of beds, the hotel rate, the existence of the following facilities: restaurant, playroom and pool (coefficient of determination r2 ~ 70%).

So as to identify the characteristic Hellenic hotel, a frequency analysis has been made. According to the results, the majority (70.7%) represent a classical hotel, located by the sea (74.7%), rated as a 2-star hotel (69.7%) that operates annually (43.6%). In terms of energy features, most of them use air-conditioning (71.5%) for cooling purposes, do not have a pool (74.1%), neither a restaurant (69.9%) or conference centre (96.6%) or meeting (92.5%) or play rooms (91.2%). However, when the hotel database is clustered according to size, the results are totally different (Table 2). According to the latter analysis the general features of each category of hotels differ from the general features. Only the characteristics of the small hotels approach the features of the total, which is quite normal considering they represent 83.03% of the total. The data presented to the above table were used to compare and determine the representative hotels of the total hotel stock.

Figure 3. Linear regression models of the hotel distribution in relation to: (a) climatic zone and (b) geographical area.

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6. The Energy Performance of Hotel Buildings A further set of data used for this paper was derived from a survey carried out by the Laboratory of Heat Transfer and Environmental Engineering, based on the energy use in 50 Hellenic hotels. The study focused on the energy and environmental performance of the hotels. Within this line of approach, information was gathered on the conditions of the hotel buildings’ envelopes and HVAC installations, as well as on the hotels’ operational patterns. The former included energy and water consumption, while the latter included the average monthly occupancy levels, operational conditions and parameters of indoor environmental quality including thermal comfort, indoor air quality and lighting. The data were collected by means of a questionnaire according to standard procedures foreseen by energy management practices for hotels and public buildings (Papadopoulos et al., 2005; Boemi et al., 2009). The questionnaire was completed within the frame of a series of in-situ visits over the last five years. The resultant database was used as a tool to support (a) the study of constructional and operational features of existing lodgings services and hotels and (b) the elaboration of interventions and improvement measures, leading to the reduction of consumption and the rational use of energy and also to the use of new and innovative technologies in this sector. Some of the most important findings of the

survey are presented briefly in the following paragraphs. 6.1 Results of the Survey The hotels audited are located in urban areas or close to major cities. Most of them are placed in the Region of Central Macedonia (58% in the prefecture of Thessaloniki and 26% in Chalkidiki) and are: 8% 1-star, 18% 2-star, 26% 3-star, 24% 4-star and 24% 5-star hotels. That allocation indicates a balance between hotel classes. Moreover, 40% are small hotels, 38% medium and finally 22% large hotels. Among the hotels audited, 55% were built before 1980, 30% were constructed between 1980 and 2000 and 15% were built after 2000 (Figure 4). Therefore, due to age alone, there should be a reasonable necessity for the majority of the buildings to adopt energy conservation measures. According to the survey’s findings, most hotel units, operating both seasonally and annually, were renovated to some extent between 2000 and 2004. This fact is quite encouraging for the attitude of the hotel sector, as it shows that hoteliers are trying to reduce their energy consumption. The results, however, do not always live up to the expectations. Electricity consumption in most hotel units varies around 300 kWh/m2 per year. This value is in accordance with results published in the literature.

Table 2. Features of the Hellenic hotel stock.

Features

small (1-100 beds

Medium (101-300 beds)

Large (301 and up beds)

Classic hotel 70.7% 92.2% 95.1% Seaside hotel 74.7% 77.5% 83.7% Class 2-star (50.1%) 3-star (39.3%) 4-star (59.6%) Operational pattern annual Seasonal seasonal Air-conditioning 71.5% 84.7% 94.9% Pool 25.9% 64.4% 83.2% Restaurant 30.1% 72.4% 95.9% Conference centre 3.4% 16.1% 35.8% Meeting room 7.5% 30.2% 53.7% Playroom 8.8% 35.7% 67.5% Mean beds 41 160 528 Mean rooms 22 84 269 Total 83.03% 13.19% 3.78%

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By comparing the results produced by the audit with the statistical values provided by other studies (Santamouris et al., 1995; Daskalaki et al., 2004; Gaglia et al., 2007) they can be regarded as fairly typical for the climatic zone, the administrative and the geographic region considered. In that sense, they can be used as an input for the top-down analysis of the hotel sector as such. Considering the lack of validated and verified data on the energy behaviour and performance of hotels, statistical analysis must be used. In that view, the following description of the real hotels can be defined as typical and representative hotels of the total building stock. 6.1.1 Small Hotel This is a 2-star, seasonal, seaside hotel, located at Ouranoupoli Chalkidiki. It is a three-storey, uninsulated building constructed in 1987. Due to the steeply sloping ground, from the front side of the building only two storeys are visible. The hotel has 24 rooms and 49 beds, with a heated area of 1,000 m2. For cooling purposes split-type room air conditioners are used, whilst hot water is provided by means of a central oil heating system with a 175 kW boiler. In 2001, the room air-conditioners were replaced by new, high energy efficiency units, rated at 2.6 kW. The windows and balcony doors are wooden with single glazing. Figure 5 depicts the variation in the electricity consumption throughout the year. It is a religious tourism hotel that operates mostly with people who travel individually or in groups for pilgrimage to Mt. Athos, mostly in the summer. That explains its seasonal character, as well as the high fluctuation of electrical consumption during the year. Average consumption is 203 kWh/m2.

6.1.2 Medium Hotel The medium hotel is an annually operating 4-star hotel, constructed in 1972, located in a sea-side suburb of the city of Thessaloniki. It is a 6-storey building oriented to the north, with a heated area of 6,053 m2. It has 87 rooms and 159 beds. Insulation exists only in the roof. For heating and hot water purposes, the hotel uses a quite new oil-fired central heating system, which was installed in 2003, with two boilers giving a total power of 1,045 kW. For cooling, 140 split units are used having a total power rating of 385 kW. The hotel’s energy demand is also determined by the existence and operation of a pool, a restaurant and meeting rooms. Even though the hotel does have a conference centre, it is separate from the main buildings and has a different electrical power provision as it was constructed 20 years later than the main buildings. Its average energy demand is about 132 kWh/m2 per year whilst the yearly fluctuation of the absolute consumption is depicted in Figure 6. 6.1.3 Large Hotel As an example of a large hotel, a 4-star hotel located near the sea was chosen. Even though the number of rooms is not so close to the statistical mean value of beds, it is still within the limits allowed by the standard deviation. Moreover, all other features of the hotel follow the descriptive statistics values of the typical hotel. The selected hotel is a seasonal hotel that operates from April until October. The hotel consists of seven buildings with 311 rooms

Figure 4. Distribution according to year of construction and operational time.

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and 652 beds. The main building is the oldest one. It was constructed in 1991 and is a 4-storey building of 6,514 m2. The other six buildings form two complexes, constructed in 2001, covering 2,946 m2 and 3,762 m2 respectively. Furthermore, there is a conference center, a 1,000 m3 volume swimming pool, a spa centre and play rooms. The major problem with the hotel is that it is an uninsulated building using, for heating and cooling purposes, only split-type room air-conditioners in each complex. The total electrical load of the hotel is 1,046 kW with an average consumption of 222 kWh/m2 per year. 7. Conclusions The lack of validated and verified data on the energy behaviour and performance of significant building groups leads to the necessity to approximate these figures by means of statistical processes. However, no statistical approximation can be safe, when it is

not based on a verified top-down analysis of the sample considered and on a bottom-up configuration of the boundary conditions, based on real data. The hotel sector is of vital importance for the Hellenic economy, so is its energy performance for the building sector. By using the data provided by means of the top-down approach, in order to obtain the necessary background on the hotel buildings’ features, the bottom-up approach has been used to provide the necessary insight to the buildings’ energy performance and to its impact on the feasibility and viability of energy conservation measures in this branch. Finally, the combination of top-down and bottom-up approach was used in order to determine the energy consumption of “typical” Hellenic hotels, with a view to producing a viable strategic plan for the improvement of the hotels’ energy and environmental performance. The first results validate this approach, which is currently being applied on a larger sample of hotel buildings.

Figure 5. Energy consumption of a small seasonal hotel (KWh).

Figure 6. Energy consumption of a medium hotel (KWh).

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Abbrevations EU European Union EPBD Energy Performance of Buildings KENAK Greek Regulation of Buildings

Energy Performance GDP Hellenic Gross Domestic Product CRES Center of Renewable Energy

Sources HVAC installations

Heating, Ventilating, and Air Conditioning installations

References Boemi SN and Papadopoulos AM: (2008). “Energy performance of the Greek hotel sector”, Proc. 40th International Heating, Ventilation Air Conditioning Conference, Belgrade, Serbia, 2-4 December. Daskalaki E and Balaras CA: (2004). “XENIOS – a methodology for assessing refurbishment scenarios and the potential of application of RES and RUE in hotels”. Energy and Buildings, 36, pp1094-1105. Gaglia AG, Balaras CA, Mirasgedis S, Georgopoulou E, Sarafidis Y and Lalas DP : (2007). “Empirical assessment of the Hellenic non-residential building stock, energy consumption, emissions and potential energy savings”. Energy and Buildings, 48, pp1160-1175. General Secretariat of National Statistic Service of Greece (ESYE), (2007); www.esye.gr (last accessed December 2007). Hellastat - Greek Statistical & Economic Data Service: (2009). http://www.hellastat.gr/en/index.html (last accessed December 2009). Hourcade J-C and Robinson J: (1996). “Mitigating factors: assessing the costs of reducing GHG emissions”. Energy Policy, 24, (10/11), pp.863-887. Institute of Touristical Predictions for Greece (ITEP) 2007; www.itep.gr. (last accessed December 2007). Isaak M and Van Vuuren D: (2009). “Modeling global residential sector energy demand for heating and air-conditiong in the context of climate change”. Energy Policy, 37, (2), pp507-521. Jacobsen HK: (1998). “Integrating the bottom-up and top-down approach to energy–economy modeling: the case of Denmark”. Energy Economics, 20, (4), pp443-461.

Karagiorgas M, Tsoutsos Th and Moiá-Pol A: (2007). “A simulation of the energy consumption monitoring in Mediterranean hotels: Application in Greece”. Energy and Buildings, 39, pp416-426. Karkanias C, Boemi SN, Papadopoulos AM, Tsoutsos TD and Karagiannidis A: (2010). “Energy efficiency in the Hellenic building sector: An assessment of the restrictions and perspectives of the market”. Energy and Buildings, 38, (6), pp2776-2784. Kavgic M, Mavrogianni A, Mumovic D, Summerfield A, Stevanovic Z and Djurovic-Petrovic M: (2010).”A review of bottom-up building stock models for energy consumption in the residential sector”. Building and Environment, 45, (7), pp1683-1697. Koopmans CC and Velde DW: (2001). “Bridging the energy efficiency gap: using bottom-up information in a top-down energy demand model”. Energy Economics, 23, pp57-75. Maciel AA, Ford B and Lamberts R: (2007). “Main influences on the design philosophy and knowledge basis to bioclimatic integration into architectural design - The example of best practices”. Building and Environment, 10, (42), pp3762-3773. Ministry of Culture and Tourism. Greek National Tourism Organisation (NTO); www.eot.gr (last accessed December 2007). Papadopoulos AM: (2007). “Energy cost and its impact on regulating the buildings’ energy behaviour”. Advances in Building Energy Research, 1, pp105-121. Papadopoulos AM, Papageorgiou PK and Giama E: (2005). “Energy conservation in the hotel sector”, Proc. 36th Congress on Heating, Refrigeration and Air Conditioning, Belgrade, Serbia, 30 Nov-02 Dec, pp167-177. Santamouris M, Balaras CA, Daskalaki E, Argiriou A and Gaglia A: (1995). “Energy conservation and retrofitting potential in Hellenic hotels”. Energy and Buildings, 24, pp65-75. Tuladhar SD, Yuan M, Berstein P, Montgomery WD and Smith A: (2009). “A top-down bottom-up modeling approach to climate change policy analysis”. Energy Economics, 31, Supplement 2, ppS223-S234. Vuuren, DP, Hoogwijk M, Barker T, Riahi K, Boeters S, Chateau J, Scrieciu S, Vliet J, Masui T, Blok K, Blomen E and Kram T: (2009). “Comparison of top-down and bottom-up estimates of sectoral and regional greenhouse gas emission reduction potentials”. Energy Policy, 37, pp5125-5139.

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Moisture Sorption Properties of Modified Porous Clays for Roof

Evaporative Cooling Applications

E. Vardoulakis1, D. Karamanis1, M.N. Assimakopoulos2, S.N. Boemi1 and G. Mihalakakou1

1Department of Environmental & Natural Resources Management, University of Ioannina,

30100, Agrinio, Greece 2Group Building Environmental Studies, Division of Environmental Physics and Meteorology,

National and Kapodistrian University of Athens, Athens, Greece

Abstract This research concentrates on evaporative cooling, a sustainable and alternative way to cool a roof surface by taking advantage of the properties of porous materials. During periods of rain or high humidity nights, water sorbents store moisture in their small pores inside their particles. During a warm sunny day, the latent heat released due to evaporation of moisture, maintains the surface temperature at low level. Lower roof temperatures contribute to smaller heat flow inside the building while reducing the cooling load. In this work, materials consisting of ordinary soil, montmorillonite and modified clays were used. Prior to moisture sorption experiments, materials were characterized by techniques including X-ray diffraction, X-ray fluorescence, thermogravimetric analysis and porosimetry. In order to determine the sorption isotherms, dry specimens were placed initially in desiccators above four different saturated salts in water solutions (32.8% to 93.6%). The modified clay was found to have the highest equilibrium state (10% after almost 4 days of sorption at high relative humidity). Also the moisture sorption rate of the modified clay was faster than the rest of the materials and equilibrium was attained in less than 12 hours. Moreover, a specific environment chamber was developed and tested for the evaporative cooling properties of the materials. The lower observed surface temperatures under simulating radiation of the modified clays in comparison to ordinary soil, indicated their significant potential for evaporative cooling applications. Key words: porous clays, evaporative cooling, heat island, energy savings. 1. Introduction The economic development and rapid urbanization in many countries during the last century resulted in microclimate changes in cities, mainly due to man-made constructions. It is expected that 70 percent of the world population will live in urban areas by 2050, and that most urban growth will occur in less developed countries (Population Reference Bureau, 2010). In recent years, higher than ambient temperatures have appeared, even in small cities. This forms a problem, especially in the summer. It has been reported that the mean temperature in Tokyo over the last 100 years has risen 3 to 4oC, while there has been an increase in the number of nights in which the temperature in Tokyo is over 25 oC, from 10 to 40 during the last decade (Okada et al., 2008). In Athens, Greece, temperature differences between urban and suburban stations of as much as10 oC have been observed (Santamouris et al., 1999). Even in smaller cities in Greece

(Kolokotsa et al., 2009), the temperature differences between the urban and rural areas seem to be high. Kolokotroni and Giridharan (2008) have recently shown that the intensity of the phenomenon in London reaches 8.9 °C on occasion, while there are time periods, where a cool island is observed. The above phenomenon is called an urban heat island. It can be quantified in terms of the heat island intensity by measuring the maximum temperature difference between urban and adjacent suburban areas. The consequences of this phenomenon include increased energy consumption for air-conditioning, thermal discomfort inside the city environment, growth in peak energy demand and financial loss (Akbari et al., 1997; Nikolaidis et al., 2009). Even heat related deaths can occur in some cases (Johnson and Wilson, 2009). The accumulation of heat inside the urban area is clearly involved with urban design and the structure density of buildings

E Vardoulakis, D Karamani, MN Assimakopoulos, SN Boemi and G. Mihalakakou ________________________________________________________________________________________________________________________

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in cities. The heat island effect is mainly caused by the reduction of wind speed, due to high-rise building development, which results in low convective heat removal. Moreover, the reduction of permeability of the ground and the use of materials that absorb and store solar radiation increases the heat capacity of cities and diminishes the cooling effect of evaporation. Due to the lack of green areas, it was reported that evapotranspiration in Tokyo has been reduced by 38% from 1972 to 1995 (Kondoh et al., 2000). Additionally, an important factor for the heat island appearance is waste heat generated from low energy efficient devices as well as from factories and automobiles. This represents anthropogenic heat. Much research has been carried out to solve the problem and reduce energy consumption in buildings. Proposals to reduce anthropogenic heat combined with proper urban design have been recommended. Constraining this problem requires a combination of countermeasures since proposed techniques so far have advantages and disadvantages. For example, reflective coatings over the roof are available to reduce cooling loads by 18 to 93% (Synnefa et al., 2007) but their reflectivity reduces by 15% during the first year of application and roof washing is necessary (Bretz et al., 1997). Roof surfaces are a key element of the heat exchange in the city environment, since they take up a great percentage of urban area and are exposed to solar radiation for many hours every day. For arid areas, almost 50% of the heat load in the building comes from the roof (Nahar et al., 1997), so it is of great importance to understand the heat movement and storage during a daytime cycle, due to radiation, conduction and convection at the roof surface (Meyn et al., 2009). Evaporative cooling is a well known technique in passive cooling design and many methods have been studied including applying a thin film of water over the roof (Sanjay et al., 2008) or by using phase change materials for heating and cooling the building (Pasupathy et al., 2007). In recent years, especially in Japan and the USA, intensive research on evaporative cooling has been undertaken but this has mainly concentrated on the use of natural porous materials for roof-surface treatment (Okada et al., 2008; Cindrella et al., 2009; Wanphen et al., 2009). According to the evaporative cooling principle, rainwater or humidity adsorbed from porous materials during rainfall or during high humidity nights can be stored inside small pores and channels

in a porous material. Conversely, during a sunny day, humidity stored inside the pores, is released and maintains roof surface temperature at low levels due to latent heat of water evaporation. Lowering the roof surface temperature is important, since heat transfer inside the building reduces as well. Evaporative cooling is considered to be the most effective method for roof surface and indoor temperature reduction (Alvarado et al., 2009) and has been proved to be practically and economically feasible especially under hot and arid climatic conditions for many houses (Chraibi et al., 1995; Tinoco et al., 2001; Liao and Chiu, 2002). Also, there are many indirect benefits including water retention during heavy rainfall, increase of thermal insulation of the building and absorption of many polluting elements. Moreover, roof material degradation due to high roof temperatures is reduced, while relative humidity in winter changes environmental climate to more wet states, resulting in a reduction of diseases spread like influenza (Okada et al., 2008). In order to choose the appropriate material for applications of evaporative cooling, a set of properties must be satisfied: • Ability to absorb water or vapour at different

relative pressure • High water retention • Thermal, hydrothermal and ageing stability • Being locally available and inexpensive • Environmentally non toxic and easily to handle • Easy construction into required shape and size

for roof application • Added ability for CO2 and toxic pollutants

sorption • Easy scale-up production It is easily understood that the evolution of new energy materials in order to exploit evaporative cooling applications in the city environment, is of great importance since this can be applied to reduce the heat island effect. Moreover, the development of porous materials is also needed in similar applications such as heat storage systems, heat pumps or refrigeration, etc. Choosing the appropriate material is critical, since each material has different hydrophilic properties and the cost of a scale-up production may be critical for application for roof materials. Up-to-date research in evaporative cooling application in buildings has been limited to natural porous

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materials (Gunhan et al., 2007; Wanphen et al., 2009; Meng et al., 2005). However, materials such as clays and modified clays seem to be suitable for roof evaporative cooling applications because they present many advantages including: • abundant raw sources (estimation of 1019 tonnes

of clays in the earth), • thermal and chemical stability, • scale-up production capability. To study the suitability of the materials, a special environmental chamber was designed. This was used to study the evaporation rate and water/moisture sorption-desorption of porous materials under controllable airflow and simulated solar radiation. 2. Experimental 2.1. Synthesis and Characterization of the Modified Clays In the present study, aluminium pillared modified clay with restored cation exchange capacity was tested as a hygroscopic material for roof cooling applications and an experimental comparison between natural soil (sieved at 500 µm), montmorillonite and porous stone was undertaken.

The pillared montmorillonite (coded Na-FPM1, Freezed Pillared Montmorillonite) was prepared according to the methods described by Karamanis and Assimakopoulos (Karamanis et al., 2007). The pillared montmorillonite had a basal spacing of 17.3 Å (as deduced from X-ray diffraction patterns), 75% of mesopores, grain size lower than 63 µm and density of 0.5 kg/m3. Photographs of the materials are shown on Figure 1. 2.2. Water Sorption Experiments 2.2.1 Sorption Isotherms In order to determine the moisture sorption isotherms (kinetics for 80 hours), a method similar to the ASTM E96-80 was used (Burch et al., 1995). Samples were initially dried for four hours in an air-circulated oven at 105 °C (MEMMERT Model 100) until the moisture was removed and a constant mass of the material was measured. Then the specimens were rapidly placed in four sealed desiccators with saturated salt solutions under controlled relative humidity and air temperature (25±1 °C). Measured humidities of the saturated salt solutions are shown in Table 1. Air temperature and humidity monitoring inside the desiccator were carried out with a TFA Dostmann/Wertheim humidity/temperature sensor.

Figure 1. The tested samples for evaporation experiments (from left to right) Na-FPM1 (white-red), montmorillonite (grey-brown), porous stone (white-grey) and soil (dark brown).

Table 1. Saturated salt solutions and relative humidities.

Salt Relative humidity (%) MgCl2·6H2O 32.8 ± 0.3

NaBr 57.6 ± 0.3 NH4Cl 78.6 ± 0.4 KNO3 93.6 ± 0.5

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To determine the sorption isotherms and kinetics, the specimens were periodically weighed with a high precision balance having a resolution of 0.1 mg (OHAUS Explorer E01140), until equilibrium with the desiccant had been established. The moisture content w was calculated from the difference of mass measurement in time and the initial dry state as:

(1) where: w = the moisture content of the specimen in gram

per gram of dry material; m = the mass of the sample in steady state

conditions; m0 = the mass of the initially dry sample. 2.2.2 Wind Tunnel Experiment The in-house designed and built wind tunnel consisted of 5 main parts comprising the settling chamber, the contraction cone, the test section, the diffuser and the fan housing (Figure 2). The settling chamber is located in the entrance of the wind tunnel and contained a honeycomb and screens to moderate the air. Air should only enter in one direction, parallel to the airflow of the tunnel so that cross-flow velocities will not cause swirling winds in the tunnel. An aramid honeycomb (Coremaster

C2 Hexagonal) was used for this purpose which was purchased from NEOTEX synthetic composites in Athens. Screens were manufactured by a local industry. An extra filter was mounted in front of the settling chamber to avoid the entrance of small particles and dust inside the wind tunnel. The contraction cone is located between the test section and the settling chamber. It was used to increase the mean velocities at the test section when high speed experiments were taking place. The test section is the chamber where experiments took place. Two holes were left open; one at the bottom side of the test section in order to allow the airflow over the porous layer surface and the second on the top side of the test section (covered by glass) for the simulated solar radiation. Irradiation was provided by a metal halide lamp (Radium HRI-BT 400W/D). Porous materials were put in a square box (material holder) surrounded by the essential insulation (Figure 3). The holder used for synthetic materials experiments had a volume of 14 cm3 and surface of 4 cm2. Holes were made on the material holder at 3 different height levels in order to record the temperature on the surface, middle level and the bottom of the porous material. T-type thermocouples (Omega TMQSS-IM075G-300) were used for this purpose. Under the material holder, a digital balance (Adamlab 753i) was used to monitor

Figure 2. Wind tunnel apparatus and main parts.

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the change of material mass over time. An acrylic square box was constructed to insulate the digital balance from any external air currents, giving the balance an accuracy of 1 mg. For airflow monitoring, an insertion mass flow meter (Sierra 620S) was used which was calibrated by Sierra Instruments. The diffuser was located between the fan and the test section and was used to reduce any air turbulence that could lead back into the test section. A relative humidity (RH) and temperature sensor (Rotronic HC2-S3C03) was fixed on the diffuser, close to the test section, for the monitoring of air temperature and RH inside the wind tunnel. At the end of the wind tunnel is the fan housing, where an axial fan (Soler & Palau HXM-350) and a speed regulator were fixed. Maximum air volume extraction capability of the wind tunnel was about 1050 m3/h. Wind flow (m3/h), relative humidity (%), temperature (°C) of air inside the tunnel, weight of sample and temperatures of the 3 thermocouples were recorded by a datalogger (Campbell Scientific CR1000) inside the laboratory. Also, in order to check the solar power over the sample, a digital solar meter with an accuracy of 1 W/m2 (Rotronics Roline TES-1333) was used at the beginning of every experiment. 2.3. Reflectivity Measurements Reflectivity of the materials is also an additional factor in lowering the roof surface temperature. It has been demonstrated that the use of reflective coatings can reduce concrete surface temperature, under hot summer conditions by, 4 °C during the

day and by 5.9 °C during the night (Synnefa et al., 2005). In order to further characterize the studied materials, spectral reflectance measurements of the samples were also performed at the Department of Applied Physics of National and Kapodistrian University of Athens, using a UV/VIS/NIR spectrometer (Varian Carry 5000). 3. Results and Discussion 3.1. Water Sorption Isotherms The kinetics of the sorption isotherms and the maximum moisture sorbed are shown in Figure 4 and Table 2, respectively. The hydrophilicity of the four specimens is quantitatively and qualitatively classified according to IUPAC based on the type of the sorption isotherms. Main properties of the material that determine water sorption include pore radius, pore geometry, surface charge and pore surface temperature (Hall et al., 2009). For montmorillonite, the sorption isotherm was of type II, since moisture uptake maintained at high levels only for relative humidity above 80%. At low relative pressure water molecules were sorbed on the external surface of the clay (R.H. <10%). Then the sorption of water molecules was accomplished on the interlayer exchangeable cations, until a monolayer was formed (10% < R.H. < 50%). Finally, at high relative pressure the multi-hydrated layers were formed after the mesopores were completely filled (Mintova, 2008).

Figure 3. Materials Holder.

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For the Na-FPM1 sample, the sorption of water in the interlayer spacing is controlled by the size and charge of the interlayer cations and the concentration and localization of the negative surface charge. The nature of the exchangeable cation plays an important role in the sorption processes and, by increasing the exchanged cationic

radius, a large surface area and a high total pore volume of clays are reached. Upon calcinations, loss of surface hydroxyls occurs and hydrophobic sites are created. But by treating the calcined sample, first with NH3 for the transformation of the liberated hydronium ions to ammonium cations and then exchanging them with the sodium ions, part of the

Figure 4. Adsorption isotherms of tested materials.

Table 2. Maximum moisture sorbed on porous stone, soil, montmorillonite and Na-FPM1.

Relative Humidity (%)

Maximum moisture sorbed after 100 h (%)

Soil Porous Stone Montmorillonite Na-FPM1 32.8 3.28 0.04 4.36 5.52 57.6 4.59 0.06 7.50 7.00 78.6 6.03 0.07 11.35 7.37 93.6 7.46 0.12 18.49 9.60

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hydrophilic sites were restored, although the available volume for water sorption was reduced due to space occupation from the sodium ions. Therefore, the sorption isotherm of Na-FPM was of type II and compared to montmorillonite, soil and porous stone offered a much more competitive application for evaporative cooling. The reason for this was the faster adsorption rates in the first 12 hours, especially at low relative pressure. It is remarkable that Na-FPM1 attained equilibrium state in less than 12 hours. According to the Hellenic National Meteorological Service, night relative humidity in Greece during summer time is between 60-70%. This indicates that more than 0.1 g of moisture per g of material can be contained on a roof surface during the night. This value seems to be an upgraded result for evaporative cooling applications compared to natural materials tested by Wanphen et al. (2009). For soil and porous stone the sorption isotherm was of type V and VII, respectively. Soil showed the behaviour of a hydrophilic material but only in high relative pressure conditions. In addition, porous stone was a hydrophobic material since even in high relative pressure presented weak sorbent-water interactions. Figure 4 illustrates the moisture kinetics comparison between the samples of montmorillonite, modified montmorillonite (Na-FPM1), porous stone and the typical soil sample. The modified montmorillonite was found to have the highest equilibrium state (10% after almost 4 days of sorption at high R.H. %). Also the moisture sorption rate of the freezed pillared montmorillonite

was faster than the rest of the materials and equilibrium was attained in less than 12 hours. Considering the proposed materials application for night moisture sorption, their sorption rates are comparable with popular materials like silica within the time frame of the night hours. 3.2. Water Sorption and Evaporation Cooling By adding 3 ml of water on the surface of the materials (7.5 mm equivalent of rainwater), the evaporation rate during the night can be observed. In the morning, materials were subjected to simulated solar irradiation for 12 hours and the cycle was repeated for one more day without adding any water mass. The radiation was provided by the metal halide lamp over the top of the wind tunnel (Figure 5) and was measured at 50 W/m2 at the holder position with the portable digital solar meter. Each of the four materials was tested for 48 hours. Air speed in the wind tunnel was set at 1.5 m/s. The weight reduction curves of the studied samples are shown in Figure 6, while the surface temperature of soil and Na-FPM1 are also presented. After the evaporation of the added water, the surface temperature of the soil reached the value of 35.3 °C during the second day. For the Na-FPM1 the surface temperature reached a value of 33.7 °C (4.5% lower). These values refer to the same relative humidity increase during the transitional night between the two cycles. By increasing the relative humidity to 55%, the maximum surface temperature of the pillared clay was even lower, at 31.5 °C.

Figure 5. Test section of wind tunnel, digital balance and T-type thermocouples.

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Porous stone presented the same behaviour as soil and montmorillonite had a slightly lower surface temperature than soil due to its better adsorption properties. The effect was more remarkable in middle temperatures where temperature differences for Na-FPM1 and soil reach 7% and 19%, for 40% and 55% R.H. respectively. Furthermore a maximum temperature reduction of 6.5 °C was achieved in the middle temperature of Na-FPM1 with respect to the soil. The fact can be explained by the greater values of latent heat vaporization and less heat flux in the modified clay compared to the soil. These values proved that the latent heat released in the environment from moisture evaporation on the Na-FPM1 surface compared to soil is much higher, allowing the pillared clay to maintain lower temperatures. An extra advantage for the Na-FPM1 is also the low material density (0.5 g/cm3) compared to soil (2.3 g/cm3), montmorillonite (2 g/cm3) and porous stone (2.7 g/cm3), which resulted in slower heat fluxes inside the material and better air circulation inside the pores (lower thermal conductivity). Further experiments of evaporative cooling under simulated conditions are in progress. By studying the weight reduction curves, among all the studied materials, montmorillonite evaporated at the highest rate for the first 8 hours (lamp off). This may occur due to the swelling taking place on the

montmorillonite surface and allows air to enter deeper in the material and remove added water at a faster rate. Furthermore all materials at the second cycle showed a weight reduction slower than the first cycle. This can be explained since added water evaporation is taking place at the beginning of the first cycle, while at the second cycle moisture sorption during the night and desorption of the remaining water are taking place at the same time. 3.3. Reflectivity Results An additional factor of lower surface temperatures under solar irradiation can be the higher reflectivity of the specific material surface compared to other materials (Synnefa et al., 2005). Therefore, the observed lower temperatures of the Na-FPM1 samples compared to soil, porous stone and montmorillonite may be also partially caused by the higher reflectivity of the material, since the grains were red-white in colour in contrast to the dark brown colour of soil and the grey-brown of the montmorillonite. Preliminary results of reflectance measurements indicate that the Na-FPM1 has much higher reflectance than the other materials in the entire wavelength spectrum (Figure 7). Therefore, further analysis for the separation of the two contributing mechanisms in lowering surface temperature as well as the study of the performance of the modified clays under the more realistic conditions of field experiments are in progress.

Figure 6. Weight reduction and surface temperature of the samples.

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4. Conclusions A key factor in reducing energy consumption in buildings is the materials used in the building sector. In the present research, four materials were tested under suitable experimental methodologies to determine their moisture sorption capability at low and high pressure and the prospect for an evaporative cooling application is examined. Modified clays were found to be an attractive material for roof cooling applications. They presented a type II sorption isotherm and full capacity of their pores was accomplished in less than 12 hours, even at low relative pressure, offering them a great advantage in night humidity adsorption. The effect was observed under simulated environmental conditions in a controlled wind tunnel and a cyclic experiment. Modified clays presented a surface temperature reduction of 3.8 °C and a maximum middle temperature reduction of 6.5 °C compared to soil. Based on the experimental results, aluminium modified clays seem to have a significant potential for evaporative cooling applications. Acknowledgment This work was supported in part by the Greek research program HRAKLEITOS II, which is co-funded by the European Social Fund and National Resources.

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Figure 7. Spectral reflectance of the tested materials.

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