INOM
EXAMENSARBETE SAMHÄLLSBYGGNAD, AVANCERAD NIVÅ, 30 HP
STOCKHOLM SVERIGE 2021,
Reuse in Demolition Projects
A Systematic Multicriteria Approach to Rank and Optimize the Reuse of Building Components in Demolition Projects
MATILDA FERLANDER ELLINOR WEDIN
KTH
SKOLAN FÖR ARKITEKTUR OCH SAMHÄLLSBYGGNAD
Master of Science thesis
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Title Author(s) Department TRITA number Supervisor Keywords
Reuse in demolition projects Matilda Ferlander & Ellinor Wedin
Real Estate and Construction Management TRITA-ABE-MBT-21408
Agnieszka Zalejska Jonsson
Reuse, Recycling, Demolition projects, Sustainability, Waste treatment, CDW, CBA, MCA, LCA, Building components.
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Abstract
The waste framework directive from the European Commission states that 70 percent of all construction- and demolition waste (CDW) should be reused or recycled. In Sweden during the year of 2018, 52,1 percent of the generated CDW was reused or recycled, but a report from Avfall Sverige showed that reuse only accounted for small fractions of this. According to the EU's waste hierarchy, waste reduction followed by reuse are the most desirable ways to handle waste. Research for how to reuse CDW is therefore considered an interesting and relevant topic for research to help achieve the goal of the waste framework directive.
The purpose of this master thesis was to further develop a Multi Criteria Analysis (MCA) model which was applied on different building components to evaluate how well suited they were for reuse considering; (1) financial return, (2) environmental impact, (3) energy consumption and (4) external aspects. The study was performed as a case study and the applied methods within the case study were interviews, a survey as well as the MCA model. To estimate aspects one to three of the MCA model, the theoretical framework consisted of a Cost Benefit Analysis (CBA) and a Life Cycle Analysis (LCA) in accordance with the European standard EN15978. The fourth aspect was evaluated with help of a survey to assess qualitative dimensions of reuse.
The study concluded that there are many challenges related to reuse in demolition projects.
Some major challenges identified were the limited time frames, absence of competence and experience among actors as well as logistical challenges. According to the results from the MCA model, there is a difference in how well suited the studied components were for reuse.
The two most beneficial components to reuse out of the investigated ones in the case study were crushed concrete and aluminum doors. It was also concluded that the MCA model is suitable to apply in this component specific context.
Examensarbete för masterexamen
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Titel Författare Institution TRITA nummer Handledare Nyckelord
Återbruk i rivningsprojekt
Matilda Ferlander & Ellinor Wedin Institutionen för fastigheter och byggande TRITA-ABE-MBT-21408
Agnieszka Zalejska Jonsson
Återbruk, Återanvändning, Återvinning, Rivningsprojekt, Hållbarhet, Recycling, Avfallshantering, CDW, CBA, MCA, LCA, Byggkomponenter
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Sammanfattning
Avfallsdirektivet från Europeiska kommissionen säger att 70 procent av allt bygg- och rivningsavfall (CDW) ska återanvändas eller återvinnas. I Sverige under året 2018 återanvändes eller återvanns 52,1 procent av den totala mängden genererad CDW. En rapport från Avfall Sverige visade dock att återanvändning endast stod för små andelar av dessa 52,1 procent. Enligt EU:s avfallshierarki är avfallsminimering följt av återanvändning de mest önskvärda metoderna för hantering av avfall. För att uppnå målet i avfallsdirektivet är studier kring återbruk av CDW ett intressant och relevant ämne.
Syftet med detta examensarbete var att vidareutveckla en MCA-modell (Multi Criteria Analysis) som tillämpades på olika byggkomponenter för att utvärdera hur lämpliga de var för återanvändning. Fyra aspekter togs i beaktning i modellen, nämligen (1) finansiell avkastning, (2) miljöpåverkan, (3) energiförbrukning och (4) externa aspekter. Studien utfördes som en fallstudie och de tillämpade metoderna inom fallstudien var intervjuer, en enkät samt utförandet av MCA-modellen. Det teoretiska ramverket för att uppskatta aspekterna ett till tre i MCA- modellen var en kostnadsnyttoanalys (CBA) och en livscykelanalys (LCA) som utfördes i enlighet med den europeiska standarden EN15978. Den fjärde aspekten utvärderades med hjälp av en enkät för att bedöma de kvalitativa dimensionerna av återanvändning.
Slutsatsen av studien var att det finns många utmaningar relaterade till återanvändning i rivningsprojekt. Några stora utmaningar som identifierats var begränsade tidsramar, avsaknad av kompetens och erfarenhet bland aktörer samt logistiska utmaningar. Enligt resultaten från MCA-modellen finns det en skillnad i hur väl lämpade de studerade komponenterna var för återanvändning. De två mest fördelaktiga komponenterna att återanvända av de undersökta i fallstudien var krossad betong och aluminiumdörrar. Vidare drogs slutsatsen att MCA- modellen är lämplig att använda i detta komponentspecifika sammanhang.
Acknowledgement
This Master Thesis of 30 credits has been conducted at the Department of Real Estate and Construction Management during spring 2021 and is the final step of the education at The Royal Institute of Technology KTH, in Stockholm.
First and foremost, we would like to thank our supervisor from The Royal Institute of Technology, Agnieszka Zalejska Jonsson, for her help and guidance. We would also like to thank our supervisor at NCC Sverige AB, Henrik Löwfenborg, who helped us to discuss key issues related to the study.
We would also like to thank all interview respondents and those who participated in the survey for taking time to participate in the development of this project. This study would not have been possible without the input and knowledge you shared.
Stockholm, June 2021
Matilda Ferlander & Ellinor Wedin
Table of Content
1 Introduction 1
1.1 Background 1
1.2 Purpose 2
1.3 Limitations 2
2 Literature review 4
2.1 Waste Hierarchy 4
2.1.1 Buildings as Material Resources 5
2.2 Waste Treatment 5
2.3 Barriers for Reuse 6
2.4 Opportunities for Reuse 7
2.5 Focus Areas in Reuse Literature 8
2.5.1 Environment focus 9
2.5.2 Management focus 9
2.5.3 Sustainability focus 10
3 Theoretical Framework 12
3.1 Cost Benefit Analysis 12
3.2 Life Cycle Assessment 12
3.2.1 The European Standard EN15978 13
3.3 Multi Criteria Analysis 17
3.3.1 Financial Return 18
3.3.2 Environmental Impact 18
3.3.3 Energy Consumption 19
3.3.4 External Benefits 20
4 Method 22
4.1 Case Study 22
4.1.1 The Studied Demolition Project 23
4.2 Interviews 24
4.2.1 Semi-structured interviews 24
4.2.2 Conducted Interviews 26
4.3 Questionnaire 27
4.3.1 Implementation of the Survey 28
4.4 Multi Criteria Analysis 28
4.4.1 Financial Return 29
4.4.2 Environmental Impact 31
4.4.3 Energy Consumption 31
4.4.4 External Aspects 34
4.4.5 Analysis of Results 36
5 Results 40
5.1 Key Takeaways from Interviews and Project Documentation 40
5.2 Multi Criteria Analysis 42
5.1.1 Financial return 42
5.1.2 Environmental Impact 44
5.1.3 Energy Consumption 45
5.1.4 External Aspects 46
6 Analysis 49
6.1 Approach 1: Pricing Emissions and Energy Usage 49
6.2 Approach 2: Ranking the Results 52
6.3 Final Rankings and Comparisons 53
7 Discussion 54
7.1 Discussion of Results 54
7.2 Discussion of MCA Model 57
8 Conclusion 63
8.1 Future studies 64
References 65
Appendix 1 68
Appendix 2 105
Appendix 3 108
List of Figures
Figure name Description Page
Figure 1 The EU’s waste hierarchy. Source: (European Commission, 2010) 4 Figure 2 Material flows of CDW and its related waste treatment methods. Source:
(Palm et al., 2015)
6 Figure 3 ISO 14040 Life Cycle Assessment framework. Source: (Curran, 2015) 13 Figure 4 The modules in EN 15978 and how they are connected to each other.
Source: (Gerhardsson et al., 2020)
14 Figure 5 The modules in EN 15978 and the different activities in each module.
Source: (Gerhardsson et al., 2020)
14 Figure 6 Ding’s model for the sustainability index. Source: (Ding, 2007) 18 Figure 7 Units for the different aspects of the MCA model in the analytical
Approach 1 and how they are derived.
37 Figure 8 The principle of the analytical Approach 1a, where the monetary values of
the three first scores compiled into one value generates the final monetary score for each material in the MCA model.
38
Figure 9 The principle of the analytical Approach 1b, where the monetary values of the three first scores are weighted together with the fourth aspect of the MCA model to generate the final weighted score for each material.
38
Figure 10 The principle of the analytical Approach 2, where all the aspects of the MCA are ranked between 1 to 7 to generate the final weighted score for each material.
39
List of Tables
Table name Description Page
Table 1 Savings in money, waste and CO2 for different materials according to the case study from IVL. Source: (IVL Svenska Miljöinstitutet, 2018)
8 Table 2 Eight important aspects for sustainable development in project appraisal. Source:
(Ding, 2007) 20
Table 3 List of all performed semi-structured interviews in this master thesis. 27 Table 4 Aspects considered with regards to the aspect financial return in the MCA model
regarding the reuse scenario.
29 Table 5 Aspects considered with regards to the aspect financial return in the MCA model
regarding the linear scenario.
29 Table 6 Embodied energy in raw materials used relevant for the studied materials in this
master thesis. Source: (Australian Government, 2013)
33
Table 7 Topics that were brought up in the survey. 35
Table 8 Results for the aspect financial return of the MCA model for each individual material in the case study.
43 Table 9 Results for the aspect environmental impact of the MCA model for each individual
material.
44
Table 10 Results for the aspect energy consumption of the MCA model for each individual material.
46 Table 11 Results from the survey for the aspect external aspects of the MCA model.
Answers are first categorized after theme and aggregated into a final result of the total outcome for the material.
47
Table 12 The results of each component in the four aspects of the MCA model. 49 Table 13 The analytical Approach 1a in which the aspects financial return, environmental
impact and energy consumption are given monetary estimations to provide the result as a monetary score and then rank it.
50
Table 14 The analytical Approach 1b in which the monetary scores and external aspects are ranked and compiled into a final weighted score which in turn is ranked to provide the preferred order of the materials for reuse.
51
Table 15 The analytical Approach 2 applied to the results of each aspect of the MCA model which generates a ranking order of the building components.
52 Table 16 A comparison of the different analytical approaches and the different ranking
orders that they generated.
53
1
1 Introduction
1.1 Background
The construction- and real estate sector currently accounts for 19 percent of the total emissions in Sweden (Boverket, 2021a). Furthermore, it is responsible for 31 percent of all waste generated within the country (Boverket, 2021b). As of the year 2018, there were 13 million tons of waste generated from construction and demolition, 6 percent of this waste were also classified as hazardous. According to the waste framework directive from the European Commission, 70 percent of the construction- and demolition waste should be reused, or material recycled (Naturvårdsverket, 2020). In 2018, the level of recycled and reused materials in Sweden within this sector was 52,1 percent and the share is increasing, but the country is still far from achieving the set goal of 70 percent. This could be explained by large amounts of material still going to landfills, energy recycling of wood as well as by shaft masses and other heavy waste types being handled by non-licensed recycling plants which are not included in the statistics (Naturvårdsverket, 2020).
According to the waste hierarchy, waste reduction followed by reuse are the most desirable ways to handle waste (European Commission, 2010). Reuse is defined by Avfall Sverige as
“an action that means that a product or component that is not classified as waste can be used again to fulfill the same function as it was originally intended for” (Avfall Sverige, 2019). The rate of reuse for building materials in Sweden today is low and a yearly report from Avfall Sverige showed that only small fractions are reused but that an exact amount is difficult to estimate (IVL Svenska Miljöinstitutet, 2020). Another study published by IVL also shows that there is in fact a high potential for reuse of components in construction projects (Almasi et al., 2018).
There are several reasons for the large amount of waste generated in the construction industry, among others these reasons are of a technical, environmental, economic, and regulatory origin (te Dorsthorst and Kowalczyk, 2001). A management focus on reuse is also common in earlier studies, such as in the study by Butrs and Fasih (2020). Solutions and opportunities for improvement of reuse are complex combinations of several aspects. To make sense of this complexity, it might be useful to have different focus areas within different studies which means that the issue of reuse within the construction sector must be tackled from several points of views. There is a limited number of existing studies that focus on decision making tools on how to value and prioritize reuse of materials in construction projects from different perspectives. Therefore, this study will focus on how reuse of building components can be improved by presenting a model to rank components suitable for reuse in an effective and efficient way mainly from an environmental and financial perspective. The applied model will be a further development of a Multi Criteria Analysis (MCA) model originally presented by Ding (2007). This study will apply the model into a new, component specific context instead of applying it on the outcome from a whole project. The model is applying a holistic approach for assessment of how reuse of building components could be implemented to generate the
2 highest total benefit considering environmental, financial, and external aspects. This model is tested by using a case study on a recently performed demolition project.
1.2 Purpose
The aim of this master thesis is to further develop a Multi Criteria Analysis (MCA) model found in previous research by Ding (2007) to a new component specific context. This application of the model can be used for assessing and ranking different building components relevant for reuse in demolition projects. Decision makers and managers can use this model as a tool to evaluate what materials to focus on if applying reuse in a demolition project. The MCA model will evaluate the building components based on four aspects, namely (1) financial return, (2) environmental impact, (3) energy consumption and (4) external aspects. A further explanation of the MCA model can be found in the methodological chapter.
The MCA model will be applied on a case study of one of NCC’s construction projects in which a demolition that included reuse was performed. Relevant building components for reuse will be based on what was reused in this specific case. Calculations performed within the MCA model together with interviews as well as a survey is intended to provide enough information to be able to answer the following research questions:
● In the studied demolition, what were the biggest challenges related to reuse?
● How do different building components perform if evaluated with the MCA model?
● How well-suited is the MCA model for evaluating and ranking building components that could be reused in demolitions?
1.3 Limitations
The study will focus on one recently performed demolition project in Stockholm which applied reuse. Swedish laws as well as EU regulations and directives regarding reuse is seen as a basis for the work. The study will be limited to solely focus on project specific components that were reused in the project of the case study as well as project specific circumstances and conditions for reuse.
Another limitation for this study is that the focus is on the demolition stage regarding reuse.
Thus, financial and environmental aspects are estimated from the perspective of the contractor which in the performed case study was NCC Building Sverige AB.
Reuse might lead to an increased need for maintenance for some components once installed in a new building after being dismantled from a demolition project. In this study, aspects of maintenance are excluded.
3 In calculations made in this study, costs related to hours worked by NCC’s white-collar workers and office workers are excluded. The reason for this limitation is that it is difficult to estimate as several people were involved, and no one worked full time solely with reuse in the demolition project but had other demanding tasks simultaneously.
4
2 Literature review
In this section of the study, a comprehensive literature review of reuse in the construction sector is presented. The literature review provides concepts related to construction waste and presents a current situation analysis. It includes what earlier research has identified as the origin of waste and different treatment methods along with barriers and opportunities for reuse.
2.1 Waste Hierarchy
In a directive from the EU, a waste hierarchy is presented which visualizes a structure for the most desirable ways of handling waste (European Commission, 2010). The directive presents five steps for waste management, these are (1) prevent, (2) reuse, (3) recycling, (4) other recovery and (5) disposal, see Figure 1.
Figure 1. The EU’s waste hierarchy. Source: (European Commission, 2010)
The first step in the waste hierarchy is the most desirable, this is to prevent waste generation by for instance using eco-friendly products and eco-design as well as avoiding hazardous substances. Waste prevention can also be linked to efficient manufacturing processes as well as affecting consumers' behavior towards choosing products with lower waste generation. If prevention is not possible, the second step in the hierarchy is reuse which concerns repeated use of the same materials and products. The third step in the hierarchy is recycling which can reduce the amount of material that goes to landfill. Where recycling is not possible, other recovery is relevant. Other recovery could be energy recovery by incineration. Poorly conducted incineration due to inefficient incineration plants or not destroying the material completely could cause release of hazardous substances to the air which can have complications to human health as well as the environment. The last step in the waste hierarchy, which is the least desirable one, is disposal through landfill. A negative impact from this type of waste management is the release of methane into the air, furthermore, it can risk contaminating the groundwater, surface water and soil (European Commission, 2010).
A literature review conducted by Joensuu et al. (2010) on 282 journal articles in the field of circular economy, built environment and urban development suggests several strategies and solutions towards a development with a smaller environmental impact than today. Among the
5 suggested strategies, a shared vision of the waste hierarchy is pointed out as a key factor. The conclusion made regarding the waste hierarchy is that focus should be on reducing the emergence of waste by promoting product-service systems in which the growth pace of the building stock is limited, and the service time of the buildings are longer. It is further concluded that several sustainability problems could be solved if a circular economy concept were applied in which more efficient and smarter solutions were introduced regarding the usage of products and buildings. The journal also concludes that more research, discussions, and empirical proof of the outcomes of a circular economy is needed in the field of the built environment (Joensuu et al., 2020).
2.1.1 Buildings as Material Resources
Since reuse is the second step in the waste hierarchy, it can be concluded that reuse is highly prioritized and that actions for increasing reuse are desirable. Furthermore, reuse would result in prevention as it will lead to less new material being needed in new construction projects. An increased share of reused materials will result in a smaller need to extract natural resources at the same time as reuse requires less of other resources such as processing, energy consumption and business resources in comparison to recycling (Kralj and Markic, 2008). Existing buildings could be looked upon as resources of material that can be utilized to minimize material consumption in future construction projects (Carvalho Machado et al., 2018). This underlines the importance for more studies on reuse to reach the goal from the European Commission that 70 percent of all construction- and demolition material should be reused, or material recycled.
2.2 Waste Treatment
In demolition projects, two types of waste can be distinguished: primary and secondary waste.
Primary waste is waste that is generated directly at a project site and secondary waste is waste generated after further waste treatment (Svenska MiljöEmissionsData, 2018). It is estimated that the total amount of construction and demolition waste is approximately 1 312 kton annually of which 1 167,2 kton is generated from the construction sector and 144,8 kton from other sectors (Palm et al., 2015).
Figure 2 visualizes a flowchart for all material flows of construction and demolition waste (CDW) that was generated in Sweden in the year 2012 and provides information about different materials’ waste treatment methods. In the figure, recycling is divided into conventional recycling and material used for construction, landfill coverage and refill. By a summation of these two categories in Figure 2 below it can be distinguished that, in total, 654,7 kton of all CDW went to recycling of some sort which corresponds to 49,9 percent of all waste. According to Palm et al. (2015), conventional recycling is usually the most beneficial form of recycling.
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Figure 2. Material flows of CDW and its related waste treatment methods. Source: (Palm et al., 2015)
According to Figure 2 above, common materials for conventional recycling are metal, glass and polymers. It can also be read out that common material to recycle as landfill coverage are mineral waste which could be for instance crushed concrete. It is also possible to conclude that the most common waste treatment method for wood is incineration. Although the statistical data is not entirely new it was still considered useful since it provides information about different materials specific waste treatment methods.
2.3 Barriers for Reuse
Reuse within demolition within the construction industry faces many challenges of different characters (Hobs and Adams, 2017). A big difficulty related to reusing products is the gap between the demand and supply of these types of products, which holds true both regarding the quality and quantity of the products. An old product or material is not likely to fulfill the same demands on functionality as a newly produced alternative that is up to date with standards and current certifications. There might also be insecurities regarding the lifespan of the reused products and its durability as little is known about these aspects. Hence, the risk of using a reused material is higher which must be taken into consideration. Another barrier of reused materials is the fact that the dismantling of demolition projects tends to have a limited time frame, complicating the issue further as extra costs for a longer demolition period is not desirable due to revenue losses. Other challenges include the extra costs related to a third part being involved in temporary storage of materials as well as transportation costs, when the demand for reused material and supply are not situated in proximity these types of barriers are high. Not having access to facilities used for recycling purposes could also be a barrier for
7 reuse. Another challenge is the rapid changes in building technologies as well as low or negative market value of the reused material (Hobs and Adams, 2017).
In general, materials that consist solely of one substance tend to be easier to reuse and recycle (Kralj and Markic, 2008). Such materials include wood, earthen materials, steel, aluminum, copper, iron, bricks, and drywall. Materials consisting of several substances such as wooden chipboards or vinyl tend not to be reusable or recyclable. Steel and wood are the two materials that tend to be the easiest to reuse, concrete can be a bit more complex (Fivet and Brütting, 2020).
The demand for different materials is dependent on the season, which could be a potential barrier for reuse (IVL Svenska Miljöinstitutet, 2020). The demand for tiles is for instance higher during spring for intended usage in greenhouses, glass, and windows while there is a higher demand for roof tiles during autumn.
2.4 Opportunities for Reuse
Reuse has many opportunities for improvement in all the project stages and there are many strategies to increase reuse. In the early phase of a new construction project, one strategy is to design for deconstruction (DfD) and adaptability, meaning that planning and design takes place in a way that facilitates the possibility to renovate and demolish the building in an environmentally friendly way in the future. Planning in early stages to incorporate reused materials and products in new buildings is key, this holds true both in the planning phase as well as in the construction phase. During the construction phase, reuse of offcuts and surplus materials within the construction project or in nearby projects and on-site sorting are two opportunities to increase reuse. At this stage, another thing to consider is the implementation of standards and testing of products. After a building's usage phase is over, pre-demolition audits with promotion of reuse are claimed to be a useful tool. Recommended strategies to increase reuse consist of for example managing supply and demand through mechanisms to match supply with demand on other sites when components cannot be used on-site.
Recommendations also include innovation in technologies regarding reuse, support of the reclamation sector and construction product declaration and recertification. Data management tools such as BIM can be modified and used to contribute to get a better understanding of reuse potential in planned projects and make the end of life outcome of the building better through more future reuse (Hobs and Adams, 2017).
Another opportunity for reuse is to shift focus to a life cycle perspective, which might be helpful to decide on what type materials and components to reuse and not. A life cycle assessment (LCA) can be made to assess the different environmental impacts from building materials during their whole lifetime and not solely in specific life cycle stages (Cai and Waldmann, 2019).
It can be discussed whether reuse of building materials and components is economically feasible. The process of reuse can be expensive as transportation, logistics, reconstruction, and
8 legal registrations can make it complex (Kartam et al., 2004). For reuse to become an attractive alternative in comparison to purchasing new products, the price point is an important aspect.
For a reused material to become an attractive option, it must be able to measure up to the quality and cost of newly produced materials (Lauritzen, 1998). Furthermore, it has been argued that not only does these aspects have to measure up, but there must also be a developed market for recycled and reused materials present (Kibert and Chini, 2000; Klang et al., 2003).
According to a guide provided by IVL regarding reuse in office spaces, there is a high circulation in office interiors. They have conducted a project where they investigated the potential for reuse in Sweden's stock of office buildings. In this project, they have based the calculations on a 2000 square meter sample office where eight common products were identified to be included in the reuse study. These products included wooden chairs, glass elements, height-adjustable desks, inner doors in wood, desk chairs, planting vessels, roof absorbers of mineral wool and textile flooring in the form of plates. The results from the study showed that the reuse of these components would save 2 million SEK, 40 tons of waste and 60 tons of carbon dioxide compared to if new components were bought. Furthermore, it concluded that the components that were the most profitable, considering all three saving aspects, to reuse were glass elements, height adjustable desks and desk chairs. The components this study investigated that are included in the case of this study are glass elements, inner doors in wood and textile carpets. The savings from these components in the sample project is presented in Table 1 below (IVL Svenska Miljöinstitutet, 2018):
Table 1. Savings in money, waste and CO2 for different materials according to the case study from IVL. Source:
(IVL Svenska Miljöinstitutet, 2018) Component Amount Monetary saving
[SEK]
Waste saved [ton]
CO2 saved [ton]
Glass elements 540 sqm 250 000 14 13
Inner doors in wood
85 pieces 150 000 4 11
Textile plates 1500 sqm 350 000 6 4
A study by Almasi et al. (2018) identifies that the reuse potential among building components is high. Glass sections, bricks, doors, windows, roof tiles, stoves, and refrigerators as well as mirrors and bathtubs have the highest potential according to the study.
2.5 Focus Areas in Reuse Literature
In the search for literature, it has been found that there are many studies related to the subject of reuse and recycling in construction projects. The topic has been tackled from several angles which all contribute to the bigger picture and understanding of the subject. It has been found that common focus areas regarding reuse are an (1) environmental, (2) management oriented or (3) sustainability oriented perspective. Below, earlier studies with these different focus areas are presented for the reader to get a broader understanding on what has been studied previously.
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2.5.1 Environment focus
Several studies have focused solely on the environmental aspects of reuse. A common way to assess reuse and recycling is to analyze the material from a life cycle perspective. This can be done through life cycle assessment (LCA) which was found in several studies. In one such study made by Thormark, the recycling potential in buildings were assessed by analyzing the total environmental impact of a material during its whole lifecycle and thereafter calculating the recycling potential of the material in question (Thormark, 2001). In a journal by Eckelman et al, a life cycle assessment of a flooring system that followed the DfD principle was made.
The study concluded that the DfD flooring made of precast concrete planks had a higher initial environmental impact and energy use but had a lower impact over its whole life cycle (Eckelman et al., 2018). A study on a similar topic was made by Densley Tingley and Davidson, in which they developed a LCA methodology that aimed at accounting for the environmental benefits of DfD. In this study, the LCA framework was applied and the end product of the study was a web-based application, Sakura, which could be used for designers and decision makers when taking decisions regarding DfD in their construction projects (Densley Tingley and Davison, 2012). In a dissertation by Roth, the environmental performance of reusing construction materials was assessed. The goal of the study was to examine when reuse and recycling might be beneficial in a context of the Swedish construction and transportation sectors. The dissertation concluded that it is not always obvious that reuse is beneficial to the environment. Whether it is beneficial or not depends on what auxiliary materials are needed in the process, the primary energy use of the process as well as the embodied energy in the material. Aspects such as transportation distance also affect the outcome. The general conclusion of the dissertation was that reuse can be beneficial from an environmental perspective under certain conditions (Roth, 2005). In another study by Palm et al, the benefits of recycling and reuse for different materials were assessed. It was concluded that for the fractions concrete and tile, the environmental benefit of recycling is low or non-existent but when reused the benefits are high (Palm et al., 2015).
2.5.2 Management focus
Another common focus in studies related to reuse in construction projects is the management oriented focus. This topic is widely spread and contains several different focuses. In a study by Trabulsi and Sofipour (2020), the reuse with a focus on actor cooperation was examined. The study aimed to find the key barriers and incentives for reuse and describe different actors’
perspectives regarding the area. The study develops a framework to describe how real estate developers and other actors can collaborate in the process and the results show that incentives to increase reuse can vary. The text points out the following main barriers; (1) lack of incentives, (2) lack of logistics and recovery facilities in proximity, (3) lack of an established procedure for quality assuring materials as well as warranty issues, and (4) the tenants’
perception of reuse (Trabulsi and Sofipour, 2020). One other study by Butrs and Fasih (2020) addresses the actor collaboration in connection to waste minimization in tenant adaptations and suggests new ways to work with reuse in renovations. According to this study, the main barriers are of an economic and social origin. Negative attitudes, a lack of stakeholders and lack of business ideas are pointed out as key barriers towards the change. The results also show that
10 many believed that increased recycling shares are linked to more expensive project costs.
According to the study, possible solutions consist of introducing measures regarding reuse investments, goals, incentives, and that education are implemented early in the planning phase (Butrs and Fasih, 2020). A study by Udawatta et al. (2015) examines how waste management can be improved in construction projects and suggests approaches towards waste minimization.
It concludes twenty six solutions and points out five of them as the most effective ones. These solutions consist of (1) lifecycle management, (2) strategic guidelines in waste management, (3) innovation in waste management decision, (4) proper design and documentation and lastly (5) team building and supervision. Furthermore, it mentions the importance of working in a way that minimizes waste as early as possible in the project (Udawatta et al., 2015).
According to a study by Shen et al. (2010), a performance checklist used in all stages of the project can be a useful and comprehensive tool to assess reuse in a holistic way. One other tool suggested in a study by Cai and Waldmann (2019) is to create a material and component bank that is linked with current methods such as life cycle assessment or environmental impact. This new circular economy system would, according to the results of their study, streamline the process of recycling and reuse. BIM is a proposed tool to simplify reuse in deconstruction according to a study by Akbarnezhad et al. (2014). This study looks at different aspects such as costs, energy use and carbon emission and develops a framework that developers can use to evaluate deconstruction strategies in different stages of the building's life cycle. Furthermore, the study concludes that reuse of materials reduces the cost and energy use of a project (Akbarnezhad et al., 2014). In a study by IVL, it is concluded that the biggest financial reuse potential can be found in bricks, timber, toilet seats and similar sanitary ware and furniture (IVL Svenska Miljöinstitutet, 2020).
2.5.3 Sustainability focus
The third focus area that could be identified was the sustainability oriented focus. Articles with a general sustainability focus tended to have a broader view on the topic and combine several aspects, mainly the three main pillars in the sustainability concept: social, environmental, and economic aspects. The texts belonging to this category had a clear focus on all three pillars. A study by Hobbs and Hurley (2001) had a focus on legislative, fiscal and policy issues related to construction and demolition. They describe specific materials and the categorization of materials in a useful way. Another article on the subject of sustainability related to reuse is written by Dorsthorst and Kowalczyk (2001). In their work, they make a case study over reuse of apartment buildings in the Netherlands. The study touched upon several subjects relating to financial, technical, and environmental aspects and concluded that the implementation of reuse is dependent on a combination of technical, environmental, economic, and regulatory aspects.
Furthermore, the study concluded that reinforced concrete elements can be reused at different levels; object renovation, element reuse, material reuse and material reuse in a useful application (te Dorsthorst and Kowalczyk, 2001). Another work on reuse related to sustainability is made by Ding (2007) which presents a sustainability index based on a multi criteria analysis (MCA) model that uses financial return, environmental impact, embodied energy, and external benefit as criterions. Ding concluded that the developed model could rank
11 options and decide on the best option for further development. In this specific case, the sustainability index was applied on different development options in Australia but it was said that the model could be applied on other related subjects, such as reuse and recycling to decide on the best way to treat different components at demolition projects as well as identifying suitable components for reuse (Ding, 2007).
After performing the literature review it can be concluded that there is a research gap consisting of the absence of studies that investigates reuse from different perspectives within one study.
Many studies solely focus on either management, environmental or financial aspects without combining them. There is also a gap identified by Ding to apply the MCA model in a component specific context to identify components suitable for reuse in demolition projects.
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3 Theoretical Framework
Within this chapter, different theoretical frameworks of relevance for this master thesis are presented.
3.1 Cost Benefit Analysis
In the search for a proper theoretical framework for the study, the first conceptual framework that was considered was a cost benefit analysis (CBA). It is a common method used in appraisal of construction projects that usually is considered beneficial and a good tool for decision- making (Belay et al., 2016). CBA can be used to visualize all costs and benefits in a project in an objective way. However, the commonly mentioned critique towards CBA has been that the tool is difficult to apply on non-monetary costs and benefits such as environmental impacts.
Hence, the CBA approach has been complemented by other aspects in attempts to make it more applicable to construction projects. One example of such an attempt is to complement CBA with a holistic, integrated multi-criteria decision-making approach. In a study by Belay et al, the shortcomings of a regular CBA were handled by applying resilience thinking, dynamics, analysis of uncertainties and system thinking. They conclude that the CBA method is inefficient as a stand-alone method and needs to be complemented by several aspects to be applicable on large infrastructural construction projects (Belay et al., 2016).
3.2 Life Cycle Assessment
Life Cycle Assessment (LCA) is described by Curran as “a holistic, cradle-to-grave environmental approach which provides a comprehensive view of the environmental aspects of a product or process throughout its life cycle” (2015). The advantages with this type of assessment is that it can identify and quantify potential environmental impacts of processes and materials as well as eventual shifts in environmental burdens from different forms and stages of a life cycle (Curran, 2015). Hence, for a comparative study between reuse and newly produced alternatives like in this study, the LCA framework is well suited.
The International Standards Organisation (ISO) has developed international standards for performing LCAs, most commonly referred to is the ISO 14040 series (Curran, 2015). Within 14040, the framework and principles for performing a LCA study is presented, the following are the main phases that should be included in such a study; (1) Goal and Scope Definition, (2) Life Cycle Inventory, (3) Life Cycle Impact Assessment, and (4) Interpretation. The conceptual framework of these steps and how they are related to one another is visualized below in Figure 3 (Curran, 2015).
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Figure 3. ISO 14040 Life Cycle Assessment framework. Source: (Curran, 2015)
According to a report by Gerhardsson et al. (Gerhardsson et al., 2020) published by IVL, there are two different ways of performing LCAs. The first one is called accounting LCA and the second one is called consequential LCA. Accounting LCA allocates the distribution of the environmental impact within a system and between the studied system and surrounding systems and is a well-suited approach for sustainability reports and accounting. This method can be used to divide environmental impact between actors, phases, and projects.
Consequential LCA evaluates the consequences of a decision or a change. This analysis uses system expansion to include all relevant environmental effects from the decisions within the system and cannot be used to divide the effects between actors, phases, or projects. In this master thesis, the environmental impacts have been evaluated by applying a consequential LCA since the total impacts of the change is what is interesting for the decision making process.
With this approach applied on reuse of specific materials in demolition projects, the results will represent the climate saving for a reused product in comparison with the impact of using a new product, which is a part of the aim to answer in this thesis (Gerhardsson et al., 2020)
3.2.1 The European Standard EN15978
EN 15978 is a European standard that provides guidelines and quantitative methods that should be applied when calculating the environmental impact of buildings with the help of LCAs (Gerhardsson et al., 2020). The environmental impact can be calculated for several impact categories, among others in greenhouse gases measured in CO2 equivalents, i.e., global warming. In EN 15978, the environmental impact of a building is divided into four information modules: A, B, C and D. The first module A is connected to the construction stage of the building which includes the environmental impact of materials that are used in the construction of the building. The second module B is related to the operational phase of the building. Here, environmental impact connected to operational activities such as maintenance and reparations are included. The third module C is a forecast scenario for how the components and materials included in the building will be handled at the end-of-life for the building. This includes activities related to demolition, waste treatment, transportation, and disposal. The last module D is not as closely related to a specific life stage of the building but is more related to the total environmental impact of decisions made regarding a building on a societal level. These four
14 modules are connected to each other as visualized in Figure 4 below. Furthermore, all activities that are included in the different modules are visualized in Figure 5 (Gerhardsson et al., 2020).
Figure 4. The modules in EN 15978 and how they are connected to each other. Source: (Gerhardsson et al., 2020)
Figure 5. The modules in EN 15978 and the different activities in each module. Source: (Gerhardsson et al., 2020)
The EN 15978 standard can be used to calculate the environmental impact of reuse in buildings (Gerhardsson et al., 2020). If the reuse is evaluated from the perspective of the building in which the reused material is built into, a certain type of calculations will be used. However, since this master thesis studies the case where material is dismantled from the studied building and reused in other buildings, the calculations needed in this case are described below.
The following section will describe the applied methodology in the case where reuse is utilized in another building than the studied object. This approach is applied for instance when material is dismantled in the studied object and reused in another building (Gerhardsson et al., 2020).
Here, the reuse can be seen as the replacement of a linear material flow that would have been the alternative to reuse. Thus, the calculations can be performed in a way so that one can visualize the overall climate saving of utilizing reuse, i.e., the environmental impact of a
15 building on a societal level caused by the decision to reuse or not in accordance with module D in EN 15978. The standard EN 15978 has not developed a specific method for how these calculations should be performed. Gerhardsson et al. (2020) proposed a way for calculating this in the report “Återbrukets klimateffekter vid byggnation” which was published by IVL in collaboration with CC Build. This is the method that will be applied in the calculations of this study. In this report by CC Build and IVL, it is proposed that the linear material flows that are being replaced with reused materials could be said to generate a climate saving. To calculate the climate saving of the reuse, the cases of reuse and linear material flows can be compared (Gerhardsson et al., 2020). Below, a reuse scenario and a linear material flow scenario are described to generate a method for calculating the overall environmental impact of reuse.
Reuse Scenario
In the reuse scenario, the environmental impact can be concluded to come from four processes;
(1) intermediate storage of material, (2) potential reconditioning of materials, (3) build-in of materials to new buildings and (4) transportations between different activities (Gerhardsson et al., 2020). In Formula 1 below, this is visualized.
𝐼𝑀𝑟𝑒𝑢𝑠𝑒 𝑠𝑐𝑒𝑛𝑎𝑟𝑖𝑜 = 𝐼𝑀𝑖𝑛𝑡𝑒𝑟𝑚𝑒𝑑𝑖𝑎𝑡𝑒 𝑠𝑡𝑜𝑟𝑎𝑔𝑒+ 𝐼𝑀𝑟𝑒𝑐𝑜𝑛𝑑𝑖𝑡𝑖𝑜𝑛𝑖𝑛𝑔+ 𝐼𝑀𝑏𝑢𝑖𝑙𝑑−𝑖𝑛+ 𝐼𝑀𝑡𝑟𝑎𝑛𝑠𝑝𝑜𝑟𝑡𝑎𝑡𝑖𝑜𝑛 (1)
In the formula, the environmental impact from intermediate storage is added when the material that will be reused needs to be stored at another site between the dismantling and reinstallation in the new building (Gerhardsson et al., 2020). The environmental impact from intermediate storage is dependent on the temperature and source of heating of the warehouse in which the material is being temporarily stored, how much storage space the material takes up and for how long the material is being stored in the warehouse. In the case study of this master thesis, no intermediate storage was utilized, hence, the environmental impacts from this variable will be zero and it is excluded from the applied reuse scenario formula (Gerhardsson et al., 2020).
The second variable in the formula is reconditioning. This variable is dependent on the added materials and processes that are used to recondition the reused components (Gerhardsson et al., 2020). The environmental impact of producing and transporting the added material is added to the environmental impact of the reused components. In the study by IVL and CC Build, repainting is excluded from this variable with the motivation that the same activity would have been present if choosing a newly produced alternative instead of the reused component.
Furthermore, impacts from washing the components for reuse are negligible. Hence, most of the impact from this variable comes from the replacement of material parts (Gerhardsson et al., 2020). In the case study in this master thesis, some components were resold in their current condition leading to the environmental impact from reconditioning being zero. Other materials had processes related to reconditioning such as depolymerization and in these cases the impact from reconditioning will be included in the calculations.
The third variable of the formula is build-in. In the example in the study by IVL and CC Build, the assumption is that the environmental impact of installing a reused material in a new building is the same as if a newly produced option was to be installed (Gerhardsson et al., 2020). Hence,
16 the impact of this post is assumed to be zero as the same processes would be needed regardless of the choice between reused or newly produced materials. The same assumption has been made in the case of this study.
The fourth variable of the reuse scenario is transportation. The environmental impact of transportation is dependent on what type of vehicle that is used for transportation and what fuel it is driven by as well as its combustion rate (Gerhardsson et al., 2020). Furthermore, the loading efficiency of the vehicles and the transportation distance are important for the calculations. Transportation should be calculated between all processes where transportation occurred. In the performed case study, some materials were transported directly from the demolition site to the end customer, other materials were sent away for reconditioning before being resold to the customer and some were also used on-site. This differs from the example from the report by IVL and CC Build where transportations were needed in three stages before the reused material could be installed in the new building.
The formula for the reuse scenario in the case study of this thesis will be similar to the one from the report by CC Build and IVL. However, as intermediate storage was not used and the build-in does not affect the total environmental impact these two posts will be excluded. The final Formula 2 is visible below.
𝐼𝑀𝑟𝑒𝑢𝑠𝑒 𝑠𝑐𝑒𝑛𝑎𝑟𝑖𝑜 = 𝐼𝑀𝑟𝑒𝑐𝑜𝑛𝑑𝑖𝑡𝑖𝑜𝑛𝑖𝑛𝑔+ 𝐼𝑀𝑡𝑟𝑎𝑛𝑠𝑝𝑜𝑟𝑡𝑎𝑡𝑖𝑜𝑛 (2)
Linear Scenario
In the linear scenario, the environmental impact comes from (1) waste treatment, (2) new production and (3) transportation (Gerhardsson et al., 2020). Below, the environmental impact of the linear scenario is described by Formula 3.
𝐼𝑀𝑙𝑖𝑛𝑒𝑎𝑟 𝑠𝑐𝑒𝑛𝑎𝑟𝑖𝑜= (𝐼𝑀𝑤𝑎𝑠𝑡𝑒 𝑡𝑟𝑒𝑎𝑡𝑚𝑒𝑛𝑡+ 𝐼𝑀𝑡𝑟𝑎𝑛𝑠𝑝𝑜𝑟𝑡𝑎𝑡𝑖𝑜𝑛)
+ (𝐼𝑀𝑛𝑒𝑤 𝑝𝑟𝑜𝑑𝑢𝑐𝑡𝑖𝑜𝑛+ 𝐼𝑀𝑡𝑟𝑎𝑛𝑠𝑝𝑜𝑟𝑡𝑎𝑡𝑖𝑜𝑛) (3) There are no clear guidelines in the report from CC Build and IVL on whether waste treatment and its related transportation should be included in the linear scenario or not. In the case of this thesis, the posts related to waste treatment will be included since the alternative would have been to send the reused components to waste treatment. The post for waste treatment includes the dismantling or demolition, the handling of residual waste and disposal (Gerhardsson et al., 2020). Calculations for this are similar to the calculations conducted in the accounting-LCA, especially in module C in the stages C1-C4, see Figure 5 above. Transportations related to waste treatment are often relatively local but will be estimated according to the invoices found for the case study. In this study, it has been decided to exclude the environmental impact from deconstruction of building material in step C1 of the EN 15978 standard due to the limited data from the demolition case and the fact that the components would have been demolished in a similar way even if they were not to be reused.
17 The post for new production includes raw material supply and manufacturing (Gerhardsson et al., 2020). Calculations that need to be performed for this post are similar to once in the accounting-LCA, especially in module A in the stages A1-A3, see Figure 5 above.
Transportations related to new production is often extensive and international. Similar to the reuse scenario, environmental impact of transportations depends on the type of vehicle and fuel, transportation distance and loading efficiency in the vehicle.
As the calculations needed for the linear scenario are quite standardized and commonly used in this type of assessments, the method for conducting these will be similar to the method applied in the manual from CC Build and IVL written by Gerhardsson et al. (Gerhardsson et al., 2020).
Total Climate Saving
The total effect of reuse is obtained by calculating the difference between the environmental impact of the reuse scenario and the linear scenario. This will generate a climate saving, which is the total effects of reuse. Formula 4, which can be used for calculating the climate saving when reuse is utilized in another building than the studied object, is visualized below.
𝐶𝑙𝑖𝑚𝑎𝑡𝑒 𝑠𝑎𝑣𝑖𝑛𝑔 = 𝐼𝑀𝑙𝑖𝑛𝑒𝑎𝑟 𝑠𝑐𝑒𝑛𝑎𝑟𝑖𝑜− 𝐼𝑀𝑟𝑒𝑢𝑠𝑒 𝑠𝑐𝑒𝑛𝑎𝑟𝑖𝑜
= ((𝐼𝑀𝑤𝑎𝑠𝑡𝑒 𝑡𝑟𝑒𝑎𝑡𝑚𝑒𝑛𝑡+ 𝐼𝑀𝑡𝑟𝑎𝑛𝑠𝑝𝑜𝑟𝑡𝑎𝑡𝑖𝑜𝑛) +(𝐼𝑀𝑛𝑒𝑤 𝑝𝑟𝑜𝑑𝑢𝑐𝑡𝑖𝑜𝑛+ 𝐼𝑀𝑡𝑟𝑎𝑛𝑠𝑝𝑜𝑟𝑡𝑎𝑡𝑖𝑜𝑛))
−( 𝐼𝑀𝑟𝑒𝑐𝑜𝑛𝑑𝑖𝑡𝑖𝑜𝑛𝑖𝑛𝑔+ 𝐼𝑀𝑡𝑟𝑎𝑛𝑠𝑝𝑜𝑟𝑡𝑎𝑡𝑖𝑜𝑛) (4)
3.3 Multi Criteria Analysis
To make up for the shortcomings of a CBA, a multi criteria analysis (MCA) can be utilized. In an MCA, weighted scores are used to evaluate different aspects within a construction project.
MCA has become a useful tool to apply in environmentally sensitive projects (Ding, 2007). In a study by Ding, an MCA model was used to create a sustainability index that was used to determine which out of three projects was the best option for construction according to the model. The study concludes that the MCA model and sustainability index are suitable tools in the evaluation of different investment decisions in construction projects. It also concludes that the model has potential to be applied in different contexts, such as in demolition projects or in the choice between specific materials (Ding, 2007).
In the MCA model presented by Ding (Ding, 2007), four aspects were used to evaluate different construction options. These four aspects are (1) financial return, (2) environmental impact, (3) energy consumption and (4) external benefits. A conceptual figure of this model is visualized below in Figure 6.
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Figure 6: Ding’s model for the sustainability index. Source: (Ding, 2007)
3.3.1 Financial Return
In the model, financial return is measured by discounting the evaluated total costs and benefits of a project (Ding, 2007). In the study by Ding, the discounted cash flow (DCF) approach is applied to estimate the total monetary value of three different options of a project. Estimations of the net present value (NPV) and benefit-cost ratio (BCR) were used on the proposed development at three different discount rates to estimate which option to choose in the different scenarios. A high NPV and a BCR greater than one indicated that the proposed development option was financially profitable (Ding, 2007).
Ding’s approach for estimating financial return is not considered suitable once applying the model to the component specific context of this study. Thus, a different approach to evaluate the financial return is needed. It was concluded that the most appropriate way to evaluate the aspect of financial return would be to look at the total economic outcome of reusing a material or component in a demolition project and then comparing it to a traditional demolition project's total economic outcome with linear material flows.
3.3.2 Environmental Impact
Within the MCA model of Ding (Ding, 2007), the environmental impact is assessed by analyzing the long-term negative impact on the environment by considering different criteria and sub-criteria. These criteria have been rated by experts in the building sector depending on their impact. A low score indicates a low impact while a higher score implies that the environmental impact is higher. Hence, a material with a low score is the most desirable.
According to Ding's model, the main criteria were divided in manufacture, design, disposal, construction, and site context. These criteria in turn have their own sub-criteria which are tangible measurements such as the amount of virgin materials used and greenhouse gas generation (Ding, 2007).
19 For this aspect, the study by Ding does not inform the reader if or how the sub-criterion was calculated. As limited information about Ding’s approach was found, this study will apply approaches on how to assess environmental impacts from more recent research. As mentioned in the literature review, recent research tends to focus on assessing materials environmental impact through LCA. The LCA framework enables a systematic approach for the user to assess a material through different environmental impact categories. For the MCA model it has been decided to focus on assessing material’s environmental impact through LCA with the guidelines provided by the European standard EN 15978 as a basis. The estimated environmental impact will be measured in CO2 equivalents, also known as global warming, as it is a well-known concept among people of all ages and educational backgrounds. Global warming is also a commonly discussed concept within the construction sector and is used for instance in certification systems like BREEAM (Taylor, 2015).
3.3.3 Energy Consumption
For this aspect of the MCA model, the embodied energy and operational energy consumption was calculated over the whole life span of the project in the study by Ding (Ding, 2007). The study measured energy consumption as annualized gigajoules per square meter of gross floor area to make the comparison between the projects. These aspects were measured over a period of 40 years, which was the estimated lifespan for the proposed development (Ding, 2007).
The total energy consumption, 𝐸𝐶, was calculated with the following formulas:
𝐸𝐶 = 𝐸𝑒+ 𝐸𝑜 (5)
𝐸𝑒 = 𝐸𝑚+ 𝐸𝑡+ 𝐸𝑝 (6)
Where 𝐸𝑒 is the embodied energy, 𝐸𝑜is the operational energy, 𝐸𝑚 is the manufacturing energy of building materials, 𝐸𝑡 is the energy for transportation and 𝐸𝑝 is the energy used in various processes.
In the MCA model adapted for this thesis, the energy consumption will be measured as megajoules per unit to be able to evaluate the selected components. The approach in Ding’s model is in many ways applicable to this component specific analysis. However, the energy consumption is centered around the specific material’s energy consumption instead of the whole buildings. Furthermore, solely the differences between the reuse scenario and the linear material flow scenario are considered in accordance with what was discussed in chapter 3.2.1 The European Standard EN15978. This is similar to the approach for evaluating environmental impact with the difference that the unit used for the energy consumption assessment is megajoules instead of kg CO2 equivalents. Results from this aspect will be expressed as an energy saving generated by reuse. The application of the EN15978 standard for estimating the energy saving is described in chapter 4.4.3 Energy Consumption as it is a methodological approach developed by the authors of this study rather than an already developed theoretical framework.
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3.3.4 External Benefits
In addition to the three aspects described above in this chapter, eight other aspects for a sustainable development in project appraisal were identified by Ding (2007). These aspects are listed in Table 2 below and were combined into a fourth category called external benefits.
Table 2. Eight important aspects for sustainable development in project appraisal. Source:(Ding, 2007)
Aspect Performance based / Intangible
1. Aesthetics/visual impact – project image Intangible
2. Functional layout – planning efficiency and flexibility Performance based 3. Heritage preservation – preservation of existing
requirements
Performance based
4. Maintenance/durability – low ongoing maintenance requirements
Performance based
5. Project life span – projects that are long lasting Performance based 6. Recycling/refurbishment potential – reuse of building
materials
Performance based
7. Social benefits – positive externalities, e.g., entertainment, tourism
Intangible
8. User productivity gains – efficiency of project users Performance based
The reason for combining these aspects into one category was that the model would have been too complex if all the remaining eight aspects had been added as separate categories (Ding, 2007). External benefits consist of both performance based as well as intangible aspects which is also visualized in Table 2 above. The category external benefits were used in Ding's MCA model to refer to the positive contribution a project may have on the environment with regards to improved living standard during the usage phase of the building's lifetime. The valuation of such aspects can be complicated as there are no clear guidelines for how to appraise non- monetary aspects, this is also a motivation for the usage of an MCA model where weights can be applied to these types of dimensions. In the study, seven people in the project with different skills and roles were questioned to rate the sub-criteria related to the external benefits on a scale from 1-5. The higher the score, the higher the importance of the external benefit (Ding, 2007).
As the application of the model will be different for this study compared to the one from Ding, so will the fourth aspect of the MCA model. It has been decided to rename this aspect from External Benefit to External Aspects as it was found that not all external aspects necessarily were beneficial. By doing so, it is possible to adjust the fourth aspect to the component specific context. The approach for assessing the external aspects will be similar to Ding’s model using a survey that will be sent out to professionals within the field of construction and reuse. The survey will consist of four questions and under each question the respondents will be asked to
21 rate the selected materials individually between one to five based on their expertise and work experience.
Although the approach is similar to Ding’s model, the asked questions will be different to fit the component specific study. As previous aspects of the MCA model were formulated as the difference between a reused material and a newly produced alternative it seems reasonable to formulate the questions in the survey in a similar manner.
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4 Method
In this chapter, the methods applied to reach the desired purpose of the master’s thesis will be presented. The chosen methods are a case study, interviews, a survey, and the MCA model.
First and foremost, the study used an inductive approach to examine the subject and be able to answer the research question. An inductive approach is suitable when the study consists of first collecting data to then develop a theory based on the collected data (Saunders et al., 2019).
The study used mixed methods in the form of triangulation, meaning mixing qualitative research with quantitative research. In this way, a more comprehensive understanding of the situation can be achieved (Cho and Trent, 2006). Qualitative data was collected through a case study that helped to identify case specific information and retain a deepened knowledge about the case dynamics. Interviews also contributed with qualitative data to the thesis. Data was also collected in a quantitative way through a survey as well as the performed calculations of environmental impact and energy consumption in accordance with the EN15978 standard that were based on a mix of quantitative and qualitative data.
4.1 Case Study
Saunders et al. describes a case study as “An in-depth inquiry into a topic or phenomenon within its real-life setting” (2019). In a case study, the case can refer to for instance a person, group of people, an organization, a process, or an event. The research in a case study is performed to understand dynamics within the subject of the case. It is a real-life setting which is something that separates this method from other research methods. Furthermore, the method is often used when what is happening within a case is not obviously related to its context (Saunders et al., 2019, p. 196-197).
An advantage with case studies is that it can result in rich, empirical descriptions and help to develop new theories (Saunders et al., 2019). It is also seen as the best way to study the interaction between a phenomenon and its context. By performing in-depth studies, the case study could generate insights and learnings from a real-life setting. The case study tends to be based on both qualitative and quantitative data to get the best understanding of a context (Saunders et al., 2019, p. 197).
A criticism of the method indicates that misunderstandings sometimes arise regarding the case study’s ability to provide generalizability as they are tied to a specific context and setting.
Hence, the extent to which results from a case study can be considered reliable and applicable in a theoretical context can be discussed. Case studies are well suited for exploratory research, but also descriptive and explanatory purposes (Saunders et al., 2019, p. 197).
