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Environmental assessment of external wall cladding

constructionBuket Metin

a& Aslihan Tavil

a

aDepartment of Architecture, Faculty of Architecture, Istanbul Technical University,

Taskisla, Taksim, 34437 Istanbul, Turkey

Published online: 07 Feb 2014.

To cite this article:Buket Metin & Aslihan Tavil (2014) Environmental assessment of external wall cladding construction,

Architectural Science Review, 57:3, 215-226, DOI: 10.1080/00038628.2013.862610

To link to this article: http://dx.doi.org/10.1080/00038628.2013.862610

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Architectural Science Review, 2014

Vol. 57, No. 3, 215226, http://dx.doi.org/10.1080/00038628.2013.862610

Environmental assessment of external wall cladding construction

Buket Metin

and Aslihan TavilDepartment of Architecture, Faculty of Architecture, Istanbul Technical University, Taskisla, Taksim, 34437 Istanbul, Turkey

(Received 8 February 2013; final version received 20 October 2013 )

Decisions made during design, construction and operation phases have effects on the environmental impacts of buildingsthroughout their life cycles. However, environmental impacts of construction process are often ignored. Construction tech-niques affect the overall environmental impacts of construction process by determining the materials, the equipment and thelabour to be utilized for the constructability, which in return affects the amount of energy use and emissions and constructionwastes generated during the construction process. This study proposes a model (environmental assessment of external wallcladding construction, EACC) to assess the effectof external wall cladding construction techniques on environmental impactsduring their construction process. In this context, first- and second-level indicators, environmental impact benchmarks andcontributing factors were defined and scores of the contributing factors were calculated. The pilot study of the EACC sug-gests that construction techniques affect not only resource and energy usage, labour health and safety during the constructionprocess, but also reuse, remanufacturing and recycling possibilities of the materials at the end of their useful life.

Keywords: external wall cladding; construction technique; construction process; environmental impact; environmentalassessment

1. Introduction

The construction industry causes environmental problems

due to its high consumption of the global resources and

its contribution to the environmental pollution through the

building construction and operation activities. According to

Edwards (1999), in the EuropeanUnioncountries, buildings

use 50% of total energy and 40% of raw material, release

50% of chemicalsharmful to the ozone layer, consume 50%

of water and cause 80% of land loss to agriculture fields.

In the Organization for Economic Co-operation and Devel-opment (OECD) area, the building sectors share of total

energy consumption is between 25% and 40% (Ryghaug

and Srensen 2009). Negative effects of buildings on the

natural environment mainly occur during their construc-

tion, as well as their operation and demolition phases.

There are many studies that have explored the relation-

ships between building operation and demolition phases,

and their impacts on the natural environment. However,

there is still a gap in the current body of knowledge about

managing the environmental impacts of construction activ-

ities prior to the construction, and more importantly during

the design phase of a building. This leads to a gap in under-

standing the whole spectrum of the built environment andits potential environmental effects. The interaction between

the building construction process and the environment is

discussed by some studies in certain aspects. Pollo and

Rivotti (2004) focuson buildingsiteand maintenance works

while developing their approach for the optimization of

Corresponding author. Email:[email protected]

design choices from the sustainability evaluation point of

view in the context of the construction process.Shen et al.

(2005)present a computer-based scoring method for the

environmental performance of the contractors during the

construction process. Rivotti (2005) develops a method

that evaluates the eco-compatibility of the technical ele-

ments used for construction activities on-site.Li, Zhu, and

Zhang (2010)develop an integrated life cycle environmen-

tal impact assessment model for construction process to

examine the twoaspects, in terms of the construction equip-ment and the ancillary materials. Gangolells et al. (2011)

propose a method to determine and rank the significance of

defined environmental impacts in a particular construction

project on the basis of their severity and the concerns of

various interested parties.Chen, Okudan, and Riley (2010)

focus on prefabrication and on-site construction methods

in the concrete buildings and investigate the awareness and

environmental concerns of the stakeholders on construction

method selection.

The construction process comprises the initial construc-

tion activities as well as the activities during maintenance,

rehabilitation and renewal processes. Pollo and Rivotti

(2004) indicate that the building process has four mainstages as off-site production, on-site production, use

and maintenance, and demolition and recycling. They

define construction and maintenance stages under on-site

production stage and estimate a buildings impact on the

natural environment during its life cycle approximately as

2014 Taylor & Francis
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216 B. Metin and A. Tavil

being 15% during the construction stage, 15% during the

maintenance stage and 10% during the demolition stage.

Furthermore, assessing the environmental impacts of the

construction process is difficult due to the fact that the

construction process consists of many sub-processes and

there is no recorded data of the comprehensive amounts of

energy use, emissionsand construction wastes (Bilec 2007).

Therefore, assessing the construction process by analysing

different construction techniques at a building element level

would provide opportunities to assess the construction pro-

cess in the context of environmental sustainability within

the life cycle of buildings.

Previous studies approach the construction process in a

holistic view by considering the environmental impacts in

general, but only a few of them investigate the problems

arising from the effect of construction techniques on the

environment. The construction technique itself has several

impacts on the environment by pointing out the inputs of

the construction process as material, equipment and labour,

which increase energy use, emissions and constructionwastes. Consequently, analysing the environmental impact

of the construction process with regard to the construc-

tion technique of a particular building component is also

important from holistic point of view.

External wall and roof systems are the two main ele-

ments of the building envelope. External wall cladding

system design and selection is one of the complicated

stages of the building envelope design, since innovation in

the building material industry and technological develop-

ments has led to a broader range and number of options

for the cladding materials as well as the construction

techniques.

This study introduces a model to be used during thedesign process, which is developed to analyse the external

wall cladding construction techniques, in order to assess

the environmental impacts of the construction processes.

The model aims to assist decision-makers, including but

not limited to the architects, contractors and owners, who

play an important role on many decisions during the design

phase regarding the construction processes. As an initial

step in this study, external wall cladding construction tech-

niques were classified by reviewing the catalogues of the

companies which are external cladding materials and sys-

tem producers in the Turkish construction sector (Metin

2010). Following the initial step, interviews with the exter-

nal wall cladding contractors were carried out in order todefine the environmental sustainability indicators, bench-

marks and contributing factors of the particularconstruction

techniques (Metin 2010). In addition, the score of each con-

tributingfactor of the construction technique was calculated

by using Benefit-Value Analysis (Tapan 1980, 2004), which

usessubjective assessmentand calculates the relative values

of the parameters developed through the assessors experi-

ence. In the end, a pilot study is conducted to demonstrate

the application of the model and to evaluate the results

accordingly.

2. Classification of the external wall cladding

construction techniques

Buildings faces have been changing due to the advances

in building technology and external wall cladding mate-

rials. Every new wall cladding material brings its own

construction technique and each technique may be different

depending on the materials properties such as dimensions,unit weight, connection type and detail design. The term

cladding is often used as a general reference to a wide

variety of naturally occurring and synthetic, or man-made,

building envelope materials, components and systems. In

building terminology, cladding is a non-structural material,

a protective layer or covering that is fixed on the outer

surface of a building or a structure to protect the build-

ing envelope against moisture and foreign elements, and to

provide aesthetic purposes. Often in building construction,

cladding or application of one material over another is done

to complete the cladding as a system. Typically, these ele-

ments are quarried, manufactured or otherwise developed

and/or altered to render them suitable for use on the exter-nal of a building or structure. The essential processes of

wall construction are cutting and assembling, plus form-

casting the cladding material by using ancillary materials

whenever necessary. Those applications have different envi-

ronmental impacts during construction process depending

on the cladding system and its construction technique in

particular.

External wall cladding materials can be assembled on

the building surface/shell by using different construction

techniques. Construction techniques differ according to

dimension, form and unit weight of the cladding material,

type and dimensions of the sub-construction and installa-

tionmaterials, building height, layers of the cladding systemsuch as thermal insulation, waterproofing, sealing, etc. In

the context of this study, cladding construction techniques

are classified according to their installation types as follows

(Table1):

Installing to a sub-construction (metal/wooden

frame etc.)

(1) with screw (Sa)

(2) with special anchorages (Sb)

(3) with standard anchorages (Sc)

(4) by welding (Sd)

(5) with adhesive (Se)

Installing to a wall core (masonry etc.),

(1) with special anchorages (Wa)

(2) with adhesive (Wb)

External wall cladding materials can be assembled on

a metal/wooden frame or metal angle/sheet, which can

be installed to the components of building structural sys-

tem (floors/columns etc.) with screws, special anchorages,

standard anchorages, by welding or with adhesive. These

construction techniques require a wooden/metal frame,

metal angle/sheet for the installation of the cladding and


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Architectural Science Review 217

Table 1. Classification of cladding construction techniques.

Construction technique details

Construction technique Plan Section Elevation

Sa Installing to a sub-construction with screw

Sb Installing to a sub-construction with special anchorages

Sc Installing to a sub-construction with anchorages

Sd Installing to a sub-construction by welding

Se Installing to a sub-construction with adhesive

Wa Installing to a wall core with special anchorages

Wb Installing to a wall core with adhesives

cannot be installed directly on the structural system or core

such as a direct installation on masonry.

Claddings can be assembled on a metal/wooden frame

with screws (Sa) by using three different ways such as con-

cealed screwing, visible screwing or embedded screwing

according to the vision that screws generate on the cladding

surface. Metal and wooden panels, cement-bonded par-

ticleboards and polyvinyl chloride (PVC) panels are the

common types of cladding systems that are assembled by

using this technique.

Claddings can also be mounted on vertical and/or hori-

zontal components by using special anchorages (Sb), which


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are designed and produced by the cladding companies for

the specific cladding component. Sb is applied by using two

different ways. Claddings can be installed with the anchor-

ages fixed on sub-construction. In addition, the anchorages

can be fixed on the sub-construction as well as reverse

side of the cladding and then they are tightened together.

Metal panels, clinker/terracotta tiles, ceramic tiles/panels,

porcelain tiles, marble, granite and PVC panels are

assembled by Sb.

Installing claddings with standard anchorages (Sc) is

especially used for glass fibre-reinforced concrete (GFRC)

panels. Metal angles are fixed on the floors or columns

and GFRC panels are assembled on these angles by using

standard anchorages. GFRC panels produced with special

metal skeleton system can also be mounted to a metal sheet

installed on the floors or columns by welding (Sd).

Claddings can also be installed to a frame with adhe-

sives (Se). A polyurethane-based adhesive is applied to the

reverse side of the cladding and assembled to the frame. Se

is generally used with a metal sub-construction. Woodenpanels and porcelain cladding tiles are generally installed

using this technique.

Wall cladding materials can also be mounted on the

wall core by using special anchorages (Wa) or adhesive

(Wb) without including a sub-construction. The cladding

materials such as granite and marble panels are prepared

with riffles on the upper and lower surfaces for providing

their assembly to the anchorages (Wa). Cement-based adhe-

sives are used for joining the small-sized cladding materials

such as brick veneers on brown-coated masonry (Wb).

Clinker/terracotta tiles, brick veneers, ceramic tiles/panels

and porcelain tiles are assembled by using Wb, while Wa

and Wb can be options for installing marble and granitepanels.

3. Methodology

Environmental assessment of external wall cladding con-

struction (EACC) aims to analyse different cladding con-

struction techniques in design phase to assess and compare

their environmental impacts during construction process.

The model focuses on the construction activities, which

can be realized during construction, use and end-of-life

phases, in order to analyse different construction tech-

niques of external wall claddings. Construction techniques

are analysed regarding their role on resource consump-tion (RC), energy consumption (EC), labour health (LH)

and waste generation (WG) during the construction activ-

ities considering their on-site application features, based

on material/equipment usage, supplementary application

requirements, installation method, labour type/safety and

waste management patterns.

The development of EACC consists of two basic stages:

first the environmental assessment parameters and second

their scores were determined. During the first stage, the

interviews with cladding contractors were conducted and

the data on the construction technique inputs, basically

material, equipment and labour were obtained. Afterwards,

on-site application features of the cladding construction

techniques were defined according to the interviews. Sub-

sequently, the assessment parameters were attributed as

the first- (In) and the second- (Inn) level indicators, envi-

ronmental assessment benchmarks (Bn) and contributing

factors (CFn) in a hierarchical order. Finally, the scores

which are the weights of the contributing factors were

determined to develop EACC, to provide the assessment

and comparison of the cladding construction techniques in

environmental sustainability point of view.

3.1. Identification of environmental assessment

indicators

Gangolells et al. (2011),Chen, Okudan, and Riley (2010),

Bilec (2007)andKim and Rigdon (1998)defined the fac-

tors affecting the environment on the basis of energy, water

and material conservation, emissions to air and wastes.

Construction techniques designate material, equipment and

labour inputs that affect the amount of energy, water and

material used, emissions and wastes created during the

construction process. Thus, previous studies ofPollo and

Rivotti (2004),Shen et al. (2005),Rivotti (2005),Li, Zhu,

and Zhang (2010),Gangolells et al. (2011),Chen, Okudan,

and Riley (2010), Bilec (2007),Kim and Rigdon (1998),

Sev (2008), Peterson and Dorsey (2000), Kibert, Sendzimir,

and Guy (2000, 2002) and Kibert (2007) were reviewed

and the environmental assessment indicators were set in

two levels as first- and second-level indicators in the con-

text of the model according to the data about material,

equipment and labour inputs related to various construc-tion techniques. First-level indicators (In) are designated as

RC,EC,LHandWG. Material,water,electricity and oil use,

site conditions, emission, noise and dust generation, land,

water and air pollution and recovery options are attributed

as second-level indicators (Inn) and they identify in what

waythe first-levelindicators affectthe environment. The on-

site application feature of cladding construction techniques

are designated as the contributing factors (CFn) since each

technique affects the environmental sustainability depend-

ing on its process. Second-level indicators are designated

for each benchmark by considering the contributing fac-

tors. The scores of the contributing factors with regard

to the environmental sustainability benchmarks are allo-cated according to the second-level indicators on which the

calculations are based (Table2).

RC and EC during the construction process should

be controlled in order to reduce environmental impacts.

According to Edwards and Hyett (as cited in Sev 2008),

approximately 50% of all global resources are consumed

by the construction industry. All building activities involve

use, redistribution and concentration of some components

of the earths resources, such as water, energy and materi-

als(Sev 2008). LH is also important during construction


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Table 2. Environmental assessment indicators.

First-level Second-level Environmentalindicator indicator assessment(In) (Inn) benchmark (Bn)

I1 RC I11 material use B1 construction typeI12 water use B2 installation method

B3 supplementaryapplications

B4 labour

I2 EC I21 electricity use B3 supplementaryapplications

I22 oil use B4 labourB5 equipment

I3 LH I31 safety precautions B5 equipmentI32 site conditions B6 installation materialI33 emission generation B7 safety managementI34 noise generationI35 dust generation

I4 WG I41 land pollution B6 installation materialI42 water pollution B8 waste management

I43 air pollution B9 reuse possibilityI44 recovery B10 recycling possibilityB11 remanufacturing

possibility

process. Volatile organic compounds (VOCs), dust and

other pollutants produced during the construction process

may be hazardous for labour and public health (Ko and

Alberico, n.d.). Dust generation, which originates from the

construction activities and vehicle emissions, threatens the

health of the laborers. Noise and vibration impacts associ-

ated with the construction activities are also hazardous for

labourers (Ko and Alberico, n.d.).WGduring the construc-

tion process is another environmental problem. Although

quantity and quality of waste generated from any specific

construction project would vary depending on the projects

circumstances and types of materials used, handling of the

wastes should be taken into account carefully (El-Haggar

2007).

3.2. Identification of environmental assessment

benchmarks and contributing factors

Environmental assessment benchmarks (Bn) defines on-site

application features and end-of-life patterns of construc-

tion techniques. During the construction process of externalwall claddings, RC, EC, LH and WG are directly related

to the construction type, installation method and mate-

rials, supplementary applications, labour type and train-

ing, equipment, safety precaution, waste management, and

reuse, recycling and remanufacturing opportunities that are

all benchmarks affecting environmental sustainability. The

contributing factors (CFn) are the options of benchmarks

according to on-site application features and end-of-life

patterns of different construction techniques. The contribut-

ing factors define the environmental impact of construction

techniques according to their relation with second-level

indicators (Table3).

Definition of the benchmarks associated with the con-

tributing factors and their relations with the second-level

indicators are explained as:

Construction type (B1) is related with the com-ponents (building structure/core/sub-construction)

where the cladding is mounted. Claddings can be

mounted on load-bearing building structural ele-

ments such as columns/beams/floors directly or on

a cast-in/masonry/frame wall core without using

any sub-construction or by using a sub-construction

consists of the metal/wooden frame system. The dif-

ference between the components where the cladding

is mounted affects the amount of the material used.

Installation method (B2) is related to the technique,

which is used for assembling the cladding on build-

ing structure, core or sub-construction. Mounting the

cladding with screws/anchorages allows ready-madematerial usage, while bonding agents such as mortar

requires on-site preparation. Therefore, installation

type affects the resource used for the preparation pro-

cess. Screws/anchorages can be used without the

necessity of any extra preparation process; however,

water and energy have to be used for preparing the

binding agents.

Supplementary applications (B3) affect the material

consumption and in case of the necessity of any

extra application such as painting, sealing, etc., the

amountof thematerialused forassembling increases.

Supplementary applications may require energy for

preparation of some components on-site to be usedin bonding and installation.

Labour (B4) is also related to the labour type and

training. Trained labour for a specific construction

technique not only affects the RC, EC and LH, but it

also affects the installation time and the quality of the

entire system. The trained and experienced workers

can provide proper use of resource and energy. More-

over, the same job can be accomplished at a qualified

level in a shorter time compared with an unskilled

labour.

Equipment (B5) used for the assemblage and mate-

rial handling at construction site affects RC and EC

during construction. For instance, certain mechanical

equipments may cause more environmental damages

and emissions due to fuel-oil consumption. Equip-

ment also affects LH due to the high noise levels they

may create.

Installation material (B6) affects the LH directly.

Bonding agents can consist of dust, VOCs and other

chemical components, which might cause hazardous

emissions.

Safety management (B7) is related to the site con-

ditions, which can be hazardous and dangerous for


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Table 3. Environmental assessment of EACC.

First-level Second-level Environmental assessmentindicator (In) indicator (Inn) benchmark (Bn) Contributing factor (CFn) Score

I1 I11,I12 B1 construction type CF1 assembling cladding on building structure 0.51CF2 assembling cladding on a core (cast-

in/masonry/frame)0.26

CF3 assembling cladding on a core usingsub-construction (vertical or horizontal)

0.14

CF4 assembling cladding on a core usingsub-construction (vertical and horizontal)

0.09

I1 I11,I12 B2 installation method CF5 assembling claddings with anchorages 0.52CF6 assembling claddings with bonding agents 0.27CF7 assembling claddings with anchorages and

bonding agents0.21

I1,I2 I11,I12,I21,I22 B3 supplementaryapplications

CF8applying the system without any extraapplication(joint sealant, painting, etc.)

0.83

CF9 applying the system with extra application (jointsealant, painting, etc.)

0.17

I1, I2 I11,I12,I21,I22 B4 labour CF10 assembling claddings by trained labour 0.83CF11 assembling claddings by unskilled labour 0.17

I2,I3 I21,I22,I34 B5 equipment CF12 assembling claddings using hand tools 0.52CF13 assembling claddings using hand tools and

electrical hand tools0.27

CF14 assembling claddings using hand tools,electrical hand tools and heavy equipment

0.21

I3,I4 I33,I35,I41,I42,I43 B6 installation material CF15 causing no emissions and contamination duringapplication (VOC, dust, etc.)

0.83

CF16 causing emissions and contamination duringapplication (VOC, dust, etc.)

0.17

I3 I31,I32 B7 safety management CF17 taking workplace safety precautions 0.83CF18 disregarding workplace safety precautions 0.17

I4 I41,I42,I43,I44 B8 waste management CF19 providing waste management plan 0.83CF20 disregarding waste management plan 0.17

I4 I41,I42,I43,I44 B9 reuse possibility CF21 construction technique is appropriate for

reusability

0.83

CF22 construction technique is inappropriate forreusability

0.17

I4 I41,I42,I43,I44 B10 recyclingpossibility

CF23 construction technique is appropriate forrecycling

0.83

CF24 construction technique is inappropriate forrecycling

0.17

I4 I41,I42,I43,I44 B11 remanufacturingpossibility

CF25 construction technique is appropriate forremanufacturing

0.83

CF26 construction technique is inappropriate forremanufacturing

0.17

labour. Conditions of the construction site affect

the labours health and their performance on-site.Workplace safety precautions have to be taken into

account, planned and controlled carefully.

Waste management (B8) is oneof thesignificant prob-

lems of the construction industry. The construction

industry is facing a challenging problem of look-

ing for landfill sites for construction and demolition

waste (Peng, Scorpio, and Kibert 1997). Therefore,

in the context of the management of the construction

wastes generated during the construction process,

providing a waste management plan should be the

major concern of the decision-makers to decrease the

amount of waste generated on-site. The basic issuesof waste management are developing a site-specific

waste management plan and include it in the contract

documents (Peng, Scorpio, and Kibert 1997). Man-

agement of the construction wastes is related with

managing the works of recycling, remanufacturing

and reusing.

Reuse possibility (B9) is associated with the

reusability capacity of the materials. It is affected

by the construction technique of the external wall

cladding system. As the construction techniques


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cause less damage during the construction and demo-

lition phases, the possibility of reusing the materials

and the installation components for another wall

cladding system would increase.

Recycling possibility (B10)isalsoaffectedbythecon-

struction technique and the components of the exter-

nal wallsystem. Thisfactor is directlyassociated with

the recyclability of materials, construction frames

and connectors of lesser quality for either the same

or different purposes by the end of their useful life.

Remanufacturing possibility (B11) is also directly

related to the construction technique. It has the same

purpose with recycling. However, it differs from

recycling, since it means remanufacturing of better

or equal quality and only to be used for the same

function.

3.3. Formulating scores of the contributing factors

The model consists of environmental assessment parame-

ters, which are set up in a hierarchical order. Thus, organi-

zation of the parameters provides using the Benefit-Value

Analysis method for the assessment of the alternatives

(Tapan 1980,2004). The Benefit-Value Analysis is a tool

for preparing decisions systematically, which takes into

account non-quantitative criteria. It uses a multidimen-

sional method to integrate quantitative criteria of many

different perspectives to measure effectiveness and becomes

more distinctive by using various criteria. (Schulze n.d.).

It uses subjective assessment and calculates the relative

values of the parameters developed through the experience

of assessors. Relative values of parameters are calculated

by weighting them according to their relative importance(Tapan 1980). According to Benefit-Value Analysis, rel-

ative values of the alternatives can be calculated by using

different methods such as Von Neumann and Morgenstern

method and Churchman and Ackoff method (Tapan 1980,

2004).

Von Neumann and Morgenstern method is used when

an alternative is preferred to another and the alternatives

can be ranked by the decision-maker (Ackoff, Gupta, and

Minas 1962). This method assumes that the true probabili-

ties are known by the decision-makers and they can identify

their preferences for the possibilities of different combi-

nations(Ackoff, Gupta, and Minas 1962; Fishburn 1964;

Tapan 2004).Churchman and Ackoff method is used for weighting

the sub-goals which have a hierarchical order (Churchman,

Ackoff, and Arnoff 1957; Tapan 1980, 2004). According

to this method, the parameters can be ranked due to their

importance and the numbers are assigned with respect to

their relative evaluation. The method makesno assumptions

about subjective probability or maximization of expected

value. It only resembles a procedure for estimating values

of set of objects where only comparative evaluations are

possible(Ackoff, Gupta, and Minas 1962).

In this study, Churchman and Ackoff method, which

is recommended for determining the weight of sub-goals

and for comparative assessment, is used since the assess-

ment parameters are in a hierarchical order and the

necessity of comparative assessment (Churchman, Ackoff,

and Arnoff 1957;Tapan 1980,2004). Subjective values are

used in developing a quantitative method for the compar-

ison of the construction techniques of the external wall

claddings. Relative values were given to the contributing

factors by taking account of the effect of the second-level

indicators on the particular construction technique. Subse-

quently, scores of the contributing factors, which are the

sub-goals for reaching the minimum environmental impact

during the construction process, are calculated.

The EACC consists of the environmental sustainability

benchmarks having two, three or four contributing factors

(Table 3). Two contributing factors determine a bench-

marks effect on the environment at an extreme level, which

can be either positive or negative. Therefore, they are

regarded as the extreme values. The other contributing fac-tors, which are more than two, affect the environment at

different levels from positive to negative. Consequently, the

calculation of the scores can be derived from two different

modelsas calculation of theextreme values(1) andthe other

values (2).

Extreme values(1):

nCF = 2,

Vmax >Vmin ,

Vmax = 1.00,

Vmin = 0.20.

Other values(2):

2< nCF n,

nCFmax = 4,

V1 > (V2 2) + + (Vn (2n 2)),

Vsn =Vn

V.

The calculation of the scores of the contributing fac-

tors (CFn) for the extreme values requires a definition of

a maximum value (Vmax) and a minimum value (Vmin)

depending on the number of the contributing factors ( nCF

)

(1). According to the Churchman and Ackoff method, Vmax,

which has the most positive effect, has to be maximum 1.00

(Churchman, Ackoff, and Arnoff 1957;Tapan 1980,2004).

The value ofVmin is defined associated with the other val-

ues. The difference between the values (V) of contributing

factors andthe total value of them shouldbe equal in order to

provide the consistency of the benchmarks for the assess-

ment. For this reason, the difference is regarded as 2 and

Vmin is defined as 0.20 in order to point out the extremity

(1). The other values are calculated by comparing thevalues

with each other and the value of CFs are adjusted after each


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comparison (2). Finally, adjusted values are normalized by

dividing with sum of the values (V) and the standardized

values of CFs(Vsn )are calculated (Churchman, Ackoff, and

Arnoff 1957;Tapan 1980,2004).

4. Application of the EACCIn the context of the study, an application is performed to

show the usability of the model. For this purpose, a spe-

cific external wall cladding material was chosen for each of

the construction technique considering the probability of the

installation varietiesof the wallcladdingmaterial during the

construction process. Widely used cladding materials for

the commercial and residential building facades in the Turk-

ish construction sector were selected for the application.

Interviews were conducted with the relevant companies to

collect data forthe assessment of theconstruction process in

particular. Environmental impact of the construction tech-

niques of cladding materials was assessed by using EACC

and results were interpreted according to the features of

each technique. Finally, results were interpreted according

to the first-level indicators, which determine the environ-

mental sustainability of construction techniques during the

construction process.

4.1. Results

The collected data from the interviews were used for EACC

and appropriate contributing factors for each of the bench-

mark were selected from the assessment table for each of

the construction technique. Then the total score of each

first-level indicator was calculated according to the relatedbenchmarks. For example, for a construction technique,

appropriate contributing factors ofB1,B2,B3andB4bench-

marks were selected and sum up to get the RC (I1) EACC

result. Finally, the results are interpreted (Figure 1). The

results of each construction technique are explained below.

Installing to a sub-construction with screw (Sa): Cement-

bonded particleboards are assembled to a vertical metal

sub-construction with screws (Sa) followed by joint sealant

application and painting. Both electrical and hand tools

are used during the process. The cladding company pro-

vides security requirements, but waste management pre-

cautions are not taken into consideration on-site. The Sa

technique for cement-bonded particleboard needs supple-mentary applications which make the recovery options

impossible, since the degrading process during reuse,

remanufacturing and recycling processes is inconvenient.

Therefore, Sa application for cement-bonded particleboard

has a higherscoreof 1.66for RC. ECandLH havethe same

score of 1.27, while the lowest score for WG is calculated

as 0.85 (Figure1).

Installing to a sub-construction with special anchorages

(Sb): Porcelain tiles are mounted to a vertical and horizon-

tal metal sub-construction (Sb), with a special anchorage

type. Both electrical and hand tools are used for the applica-

tion. The cladding company provides security requirements

but waste management precautions are not taken into con-

sideration on-site. Sb does not require any supplementary

application, which makes the recovery options possible and

provides an easier recovery process. According to these

properties, Sb application for porcelain tiles received higher

score of 3.49 for WG. EC and LH yield the same lowest

score of 1.93 and RC has the score of 2.27 (Figure1).

Installing to a sub-construction with standard anchor-

ages (Sc) and installing to a sub-construction by welding

(Sd): GFRC panels can be mounted on the metal sheet,

which is fixed to the columns and floors by using standard

anchorages(Sc) or by welding (Sd).During the construction

process, besides electrical and hand tools, heavy equip-

ments are used for lifting the panels depending on the

size and weight of the panels. The cladding company pro-

vides security requirements but does not take into account

the waste management precautions on-site. Sc technique

requires only joint sealant application, which does not affectthe recovery process directly. Although a different installing

method is needed for installing using standard anchorages

or welding, Sc and Sd techniques for GFRC panels have the

same EACC results because of the similarities in the princi-

ples of the application process. Hence, EC and LH yield the

same and the lowest score of 1.21, while RC has the score

of 2.03 and WG has the highest score of 2.83 (Figure1).

Installing to a sub-construction with adhesive (Se): Lami-

nated wooden panels are assembled to a vertical metal sub-

construction by using polyurethane-based adhesive (Se).

Electrical and basic hand tools are used for this technique.

The cladding company provides security requirements but

waste managementprecautions are not takeninto considera-tion on-site. The Se technique for laminated wooden panels

does not require any supplementary applications, which

make the recovery options possible. Consequently, EC and

LH have the lowest score of 1.93, while RC has the score

of 2.01. WG yields the highest score of 2.83 (Figure 1).

Installing to a wall core with special anchorages (Wa):

Granite panels aremounted to the wall core by using special

anchorages (Wa). The anchorages installed on the wall core

and the granite panels, which are prepared with riffles on

the upper and lower surfaces, are assembled to the anchor-

ages. Electrical and hand tools are used for the technique.

The cladding company provides security requirements, but

waste management precautions are not taken into consid-eration on-site. Wa does not require any supplementary

application, which makes the recovery options possible.

Therefore, EC and LH receive the lowest score of 1.93,

while WG has the highest score of 3.49 and RC has the

score of 2.44 (Figure1).

Installing to a wall core with adhesive (Wb): Granite pan-

els can also be installed on the wall core by using cement-

based adhesive (Wb) and hand tools are used during the

construction process. The cladding company provides secu-

rityrequirements but waste management precautions are not


10/13


Figure 1. Assessment of construction techniques.

taken into consideration on-site. Granite panels mounted

with theWb techniquecannot be recoveredbecauseof adhe-

sive usage for installation and joint sealant application. This

situation makes reuse, remanufacturing and recycling pro-

cesses inconvenient for the Wb technique. Hence, RC has

the highest score of 1.53, while WG has the lowest score of

0.85. EC and LH have the same score of 1.52 (Figure 1).

4.2. Discussion

After the assessment of each construction technique, they

were compared with each other according to the first-level

indicators to explore their impact on environmental sus-

tainability. For this purpose, first-level indicator results of

each construction technique were used as the variables for a

statistical analysis, and then means of the first-level indica-

tors were calculated (Figure2). According to the statistical

analysis, the mean of RC, EC, LH and WG indicators were

calculated as 1.996, 1.571, 1.571 and 2.453, respectively.

The means of each indicator were used as the comparison

level and the construction techniques were compared with

each other (Figure3).

I1 Resource consumption: RC indicator has a mean of

1.996(Figure 2). Installing to a sub-construction with screw

(Sa) and installing to a wall core with adhesive (Wb) are

below the mean with 1.66 and 1.53 scores, respectively.

Installing the cladding material to a sub-construction with

special anchorages (Sb), with standard anchorages (Sc), by

welding (Sd), with adhesive (Se) andto thecore with special

anchorages (Wa) areabovethe mean with thescores of 2.27,

2.03, 2.01 and 2.44, respectively (Figure3).

Construction type (B1), installation method (B2), sup-

plementary applications (B3) and labour (B4) benchmarks

affect the results of RC indicator. Wa, which has the highest

score, uses wall core for assemblage without requiring any

sub-construction thus consuming less material during the

assembly. Since only the anchorages are used without the

necessity of any supplementary materials, water and mate-rial consumption is reduced. On the other hand, in spite of

using wall core for the assembly, Wb has the lowest score

for requiringsupplementaryapplications and usingbonding

agents. This causesan increase in itsresource usage. Labour

is directly related to labour training and the trained labourer

usage during the construction process. All the interviewed

companies have labour training programmes which show

positive contributions on the overall results.

I2Energy consumption: EC indicator has a mean of 1.571

(Figure 2). Installing the cladding to a sub-construction

with screw (Sa), with standard anchorages (Sc), by weld-

ing (Sd) and installing to a wall core with adhesive (Wb)

Figure 2. Statistical analysis of results.


11/13


Figure 3. Comparison of construction techniques.

are below the mean with 1.27, 1.21, 1.21 and 1.52 scores,

respectively. Installing to a sub-construction with special

anchorages (Sb), with adhesive (Se) and to wall core with

special anchorages (Wa) are above the mean with a score

of 1.93 (Figure3).

Supplementaryapplications (B3),labour(B4) and equip-

ment (B5) benchmarks affect the results of the EC indicator.

Sc andSd have thelowest scoresfor ECby requiringsupple-

mentary application, such as joint sealant, which causes an

increase in energy use for on-site preparation of installation

materials. During Sc and Sd techniques, heavy equipment

is used because of the GFRC panel dimensions and weight,

which also increases energy use. Sb, Se and Wa have higher

scores for EC by not requiring any supplementary applica-

tion and using hand tools and electrical hand tools which

allow less energy usage during application in comparison

with Sc and Sd techniques. I3 Labour health: LH indicator has a mean of 1.571

(Figure 2). Installing the cladding to a sub-construction

with screw (Sa), with standard anchorages (Sc), by weld-

ing (Sd) and installing to a wall core with adhesive (Wb)

are below the mean with the scores of 1.27, 1.21, 1.21 and

1.52, respectively. Installing to a sub-construction with spe-

cial anchorages (Sb), with adhesive (Se) and installing to a

wall core with special anchorages (Wa) are above the mean

with the score of 1.93 (Figure3).

Equipment (B5), installation material (B6) and safety

management (B7) benchmarks affect results of LH indica-

tor. Sc and Sd techniques have the lowest scores for LH

by requiring heavy equipment usage, which causes higherlevels of noise than any conventional equipment. Sc and

Sd also require joint sealant as supplementary application

that causes dust generation during bonding agent prepara-

tion. Therefore, during Sc and Sd techniques, LH is affected

negatively. Sb, Se and Wa have higher scores for LH by

using hand tools and electrical hand tools for the process,

causing less noise than heavy equipment. Moreover, Se

requires ready-made polyurethane adhesive for the applica-

tionwhichprevents on-site preparation and dust generation.

All the interviewed companies provide safety management

and take workplace safety precautions during the construc-

tion process, which contributes positively to the overall

scores of LH.

I4 Waste generation: WG indicator has a mean of 2.453

(Figure2). Installing to a sub-construction with screw (Sa)

and to wall core with adhesive (Wb) is below the mean

with the score of 0.85. Installing to a sub-construction with

standard anchorages (Sc) by welding (Sd) and with adhe-

sive (Se) are above the mean with the score of 2.83 while

installing to a sub-construction withspecial anchorages(Sb)

and installing to a wall core with special anchorages (Wa)

are above the mean with the score of 3.49 (Figure 3).

Installation material (B6), waste management (B8), reuse

(B9), recycling (B10) and remanufacturing possibilities (B11)

benchmarks affect the results of WG indicator. Sa and Wb

have the lowest scores for WG by requiring supplemen-

tary applications as joint sealant and painting and Wb also

requires a bonding agent for the assemblage. Therefore,

supplementary applications and bonding agent usage make

the degradation process difficult for the future recoveryoptions. Moreover, bonding agent usage causes dust gener-

ation, which can cause land, air and water pollution. Sb and

Wa yield the higher scores for WG by requiring only special

anchorages for the assemblage that prevents bonding agent

usage andmakesrecoveryoptions possible without theneed

for any degradation process. Furthermore, the amount of

dust and emission creation is less in Sb and Wa when they

are compared with Sa and Wb. None of the interviewed

companies provide any waste management plan on-site,

which contributes negatively to the overall results for WG.

5. Conclusions

This research is conducted to investigate the effect of the

construction techniques on environmental sustainability

during the construction process, and the cladding systems

are selected as the focus of this study due to a variety of

construction techniques available for cladding installations.

The EACC results show that RC indicator yields the scores

varying between 1.53 and 2.44 in which installing to a wall

core with adhesive (Wb) has the lowest and installing to

a sub-construction with special anchorages (Sb) has the

highest scores. EC indicator scores vary between 1.21 and

1.93 in which installing to a sub-construction with stan-

dard anchorages (Sc) and installing to a sub-constructionby welding (Sd) have the lowest and installing to a sub-

construction with special anchorages (Sb), installing to a

sub-construction with adhesive (Se) and installing to wall

core with special anchorages (Wa) have the highest scores.

LH indicator gets scores between 1.21 and 1.93 in which

installing to a sub-construction with anchorages (Sc) and

installing to a sub-construction by welding (Sd) have the

lowest and installing to a sub-construction with special

anchorages (Sb), installing to a sub-construction with adhe-

sive (Se) and installing to wall core with special anchorages


12/13


(Wa) have the highest scores. WG indicator scores are cal-

culated between 0.85 and 3.49 in which installing to a

sub-construction with screw (Sa) and installing to a wall

core with adhesive (Wb) have the lowest and installing

to a sub-construction with special anchorages (Sb) and

installing to a wall core with special anchorages (Wa) have

the highest scores.

Results of this study demonstrate that the RC indica-

tor is mostly defined by the construction type and by the

supplementary application requirement of the construction

techniques, which affect water and material uses as the

second-level indicators. Results of the EC indicator are

mostly determined by the supplementary application and

the equipment requirement of the construction techniques,

which affect electricity and oil uses as the second-level

indicators. Equipment and installation material require-

ments affect the scores of LH indicator basically with their

influence on the second-level indicators that are emission,

noise and dust generation. When construction techniques

are compared, the biggest differences among the scoresare observed on the WG indicator. Supplementary appli-

cations and bonding agent usage make the recovery options

impossible, since degrading process during reuse, reman-

ufacturing and recycling processes becomes inconvenient.

Moreover, all of the companies, which the interviews were

conducted with, declared that they do not provide any

waste management plan for the construction site during the

construction process. Therefore, these properties cause a

big difference between the construction techniques, which

only include anchorage usage or require bonding agent and

supplementary application usage.

This study shows that the effect of the construction pro-

cess on the environmental sustainability can be assessed byweighting the process of various construction techniques

with the help of comprehensive analysis of the particular

technique. Despite the fact that the construction process

comprises a relatively short time period of the building

life cycle, it affects the environment and human, and its

role on the building life cycle cannot be underestimated.

The EACC method provides assessment and comparison

of external wall cladding construction techniques during

the design process and it helps decision-makers in reduc-

ing environmental impacts of the construction process. The

study also shows that the construction process has negative

effects on environment regarding its various aspects, such

as material and equipment inputs and construction tech-niques, which should not be underestimated to achieve a

holistic environmental sustainability in the building sector.

The EACC method considers only the external wall

cladding construction techniques. The development of

external wall cladding materials and their construc-

tion techniques are in progress and their environmen-

tal impacts of the construction process can be assessed

during the design phase with this method. The method

depends on a subjective assessment methodology; there-

fore, a methodology, which relies on quantitative data

obtained from the stakeholders of the construction indus-

try such as material producers, vendors and constructors

can also be developed. Further research is also needed

to provide a holistic assessment of the construction pro-

cess, which considers other construction techniques used

in buildings. Thus, environmental sustainability of the

construction process can be better assessed and con-

trolled prior to the construction process and during the

design phase.

References

Ackoff, R. L., S. K. Gupta, and J. S. Minas. 1962. ScientificMethod: Optimizing Applied Research Decisions. NewYork:John Wiley & Sons.

Bilec, M. M. 2007. A Hybrid Life Cycle Assessment Model forConstruction Processes. PhD diss., University of PittsburgSchool of Engineering, USA.

Chen, Y., G. E. Okudan, and D. R. Riley. 2010. Sustainable

Performance Criteria for Construction Method Selection inConcrete Buildings. Automation in Construction 19 (2):235244.doi:10.1016/j.autcon.2009.10.004.

Churchman, C. W., R. L. Ackoff, and E. L. Arnoff. 1957. Intro-duction to Operations Research. New York: John Wiley &Sons.

Edwards, B. 1999. SustainableArchitecture: European Directivesand Building Design. Oxford: Architectural Press.

El-Haggar, S. 2007. Sustainability of Construction and Demo-lition Waste Management. Chap. 8 in Sustainable Indus-trial Design and Waste Management: Cradle-to-Cradle forSustainable Development. Burlington: Elsevier AcademicPress.

Fishburn, P. C. 1964.Decision and Value Theory.New York: JohnWiley & Sons.

Gangolells, M., M. Casals, S. Gasso, N. Forcada, X. Roca,and A. Fuertes. 2011. Assessing Concerns of InterestedParties when Predicting the Significance of EnvironmentalImpacts Related to the Construction Process of ResidentialBuildings. Building and Environment46 (5): 10231037.doi:10.1016/j.buildenv.2010.11.004.

Kibert, C. J. 2007. Sustainable Construction: Green BuildingDesign and Delivery. Hoboken, NJ: John Wiley & Sons.

Kibert, C. J., J. Sendzimir, and G. B. Guy. 2000. Construc-tion Ecology and Metabolism: Natural System Analoguesfor a Sustainable Built Environment. Construction Man-agement and Economics 18 (8): 903916. doi:10.1080/014461900446867.

Kibert, C. J., J. Sendzimir, and G. B. Guy. 2002. ConstructionEcology: Nature as the Basis for Green Buildings. London:Spon Press.

Kim, J. J., and B. Rigdon. 1998. Sustainable Architecture Mod-ule:Introduction to SustainableDesign. AnnArbor:NationalPollutionPrevention Center for HigherEducation, Universityof Michigan. http://www.umich.edu/nppcpub/resources/compendia/ARCHpdfs/ARCHdesIntro.pdf

Ko, D., and J. Alberico. n.d. Reducing Environmental ImpactsDue to Construction Activities. Technotes, Issue No. 31.RWDI Consulting Engineers and Scientists. http://www.rwdi.com/cms/publications/50/t31.pdf

Li, X., Y. Zhu, and Z. Zhang. 2010. An LCA Based Envi-ronmental Impact Assessment Model for ConstructionProcesses. Building and Environment 45 (3): 766775.doi:10.1016/j.buildenv.2009.08.010.
http://dx.doi.org/10.1016/j.autcon.2009.10.004http://dx.doi.org/10.1016/j.autcon.2009.10.004http://dx.doi.org/10.1016/j.buildenv.2010.11.004http://dx.doi.org/10.1016/j.buildenv.2010.11.004http://dx.doi.org/10.1080/014461900446867http://dx.doi.org/10.1080/014461900446867http://dx.doi.org/10.1080/014461900446867http://www.umich.edu/~nppcpub/resources/compendia/ARCHpdfs/ARCHdesIntro.pdfhttp://www.umich.edu/~nppcpub/resources/compendia/ARCHpdfs/ARCHdesIntro.pdfhttp://www.umich.edu/~nppcpub/resources/compendia/ARCHpdfs/ARCHdesIntro.pdfhttp://www.umich.edu/~nppcpub/resources/compendia/ARCHpdfs/ARCHdesIntro.pdfhttp://www.rwdi.com/cms/publications/50/t31.pdfhttp://www.rwdi.com/cms/publications/50/t31.pdfhttp://dx.doi.org/10.1016/j.buildenv.2009.08.010http://dx.doi.org/10.1016/j.buildenv.2009.08.010http://dx.doi.org/10.1016/j.buildenv.2009.08.010http://www.rwdi.com/cms/publications/50/t31.pdfhttp://www.rwdi.com/cms/publications/50/t31.pdfhttp://www.umich.edu/~nppcpub/resources/compendia/ARCHpdfs/ARCHdesIntro.pdfhttp://www.umich.edu/~nppcpub/resources/compendia/ARCHpdfs/ARCHdesIntro.pdfhttp://dx.doi.org/10.1080/014461900446867http://dx.doi.org/10.1080/014461900446867http://dx.doi.org/10.1016/j.buildenv.2010.11.004http://dx.doi.org/10.1016/j.autcon.2009.10.004


13/13


Metin, B. 2010. Assessing the Construction Process of theCladding Systems in the Context of Environmental Sus-tainability. Master thesis (in Turkish), Istanbul TechnicalUniversity, Institute of Science and Technology, Istanbul,Turkey.

Peng, C., D. E. Scorpio, and C. J. Kibert. 1997. Strategiesfor Successful Construction and DemolitionWaste Recycling Operations. Construction Management

and Economics15(1):4958. doi:10.1080/014461997373105.Peterson, K. L., and J. A. Dorsey. 2000. Road Map

for Integrating Sustainable Design into Site-level Oper-ations. Report No. PNNL-13183. Pacific NorthwestNational Laboratory Operated By Battelle for the UnitedStates Department of Energy. http://infohouse.p2ric.org/ref/14/13645.pdf

Pollo, R., and A. Rivotti. 2004. Building Sustainability Evalua-tion in the Building Process: The Construction Phase. Paperpresented at the Regional Central and Eastern European Con-ference on Sustainable Building, Building Research Institute,Warsaw, October 2729.

Rivotti, A. 2005. Evaluating the Eco-compatibility of the Tech-nical Elements Used in On-site Construction Works. Paper

presented at the World Sustainable Building Conference,Tokyo, September 2729.

Ryghaug, M., and K. H. Srensen. 2009. How Energy EfficiencyFails In The Building Industry. Energy Policy37 (3): 984991.doi:10.1016/j.enpol.2008.11.001.

Schulze, L. n.d. Value Benefit Analysis. Chap. 6 in Basicsfor Planning of Logistical Systems. Capacity Building Inter-national. Accessed July 4.https://gc21.giz.de/ibt/en/opt/site/

ilt/ibt/regionalportale/sadc/inhalt/logistics/module_03/61_value_benefit_analysis.html

Sev, A. 2008. How Can the Construction Industry Contribute toSustainable Development? A Conceptual Framework. Sus-tainable Development17 (3): 161173.doi:10.1002/sd.373.

Shen, L. Y., W. S. Lu, H. Yao, and D. H. Wu. 2005. A Computer-based Scoring Method for Measuring Environmental Perfor-mance of Construction Activities.Automation in Construc-tion14 (3): 297309.doi:10.1016/j.autcon.2004.08.017.

Tapan, M. 1980.Benefit-value Analysis as an Assessment Tool inArchitecture(A book in Turkish). Istanbul; Istanbul TechnicalUniversity.

Tapan, M. 2004.Assessment in Architecture (A book in Turkish).Istanbul: Istanbul Technical University.
http://dx.doi.org/10.1080/014461997373105http://dx.doi.org/10.1080/014461997373105http://infohouse.p2ric.org/ref/14/13645.pdfhttp://infohouse.p2ric.org/ref/14/13645.pdfhttp://dx.doi.org/10.1016/j.enpol.2008.11.001http://dx.doi.org/10.1016/j.enpol.2008.11.001https://gc21.giz.de/ibt/en/opt/site/ilt/ibt/regionalportale/sadc/inhalt/logistics/module_03/61_value_benefit_analysis.htmlhttps://gc21.giz.de/ibt/en/opt/site/ilt/ibt/regionalportale/sadc/inhalt/logistics/module_03/61_value_benefit_analysis.htmlhttps://gc21.giz.de/ibt/en/opt/site/ilt/ibt/regionalportale/sadc/inhalt/logistics/module_03/61_value_benefit_analysis.htmlhttp://dx.doi.org/10.1002/sd.373http://dx.doi.org/10.1016/j.autcon.2004.08.017http://dx.doi.org/10.1016/j.autcon.2004.08.017http://dx.doi.org/10.1016/j.autcon.2004.08.017http://dx.doi.org/10.1002/sd.373https://gc21.giz.de/ibt/en/opt/site/ilt/ibt/regionalportale/sadc/inhalt/logistics/module_03/61_value_benefit_analysis.htmlhttps://gc21.giz.de/ibt/en/opt/site/ilt/ibt/regionalportale/sadc/inhalt/logistics/module_03/61_value_benefit_analysis.htmlhttps://gc21.giz.de/ibt/en/opt/site/ilt/ibt/regionalportale/sadc/inhalt/logistics/module_03/61_value_benefit_analysis.htmlhttp://dx.doi.org/10.1016/j.enpol.2008.11.001http://infohouse.p2ric.org/ref/14/13645.pdfhttp://infohouse.p2ric.org/ref/14/13645.pdfhttp://dx.doi.org/10.1080/014461997373105

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