Surveying the environmental life-cycle performance assessments: Practice and context at early building design stages

Surveying the environmental life-cycle performance assessments: Practice and context at early building design stages

Sustainable Cities and Society 52 (2020) 101879 Contents lists available at ScienceDirect Sustainable Cities and Society journal homepage: www.elsev...

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Sustainable Cities and Society 52 (2020) 101879

Contents lists available at ScienceDirect

Sustainable Cities and Society journal homepage:

Surveying the environmental life-cycle performance assessments: Practice and context at early building design stages


Thomas Jusselmea,c,⁎, Emmanuel Reyb, Marilyne Andersena,c a

Building 2050 Research Group, Ecole Polytechnique Fédérale de Lausanne (EPFL), Fribourg, Switzerland Laboratory of Architecture and Sustainable Technologies (LAST), School of Architecture, Civil and Environmental Engineering (ENAC), Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland c Laboratory of Integrated Performance in Design (LIPID), School of Architecture, Civil and Environmental Engineering (ENAC), Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland b



Keywords: Life-Cycle Assessment Context of use Early design stage User-Centred Design Obstacles

The international greenhouse gas agreements call for mitigations in the building industry. Thus, the number of scientific publications about life-cycle performance assessment (LCPA) follows an exponential trend since the 2000s. However, previous surveys highlighted that the use of these methods is still not a common practice. Hence, it is of primary importance to understand the gap between the research intensity, and its low-benefits on the practice. To that end, a set of questions has been compiled and spread as an online survey targeting architects and engineers at the European scale. Thanks to 500 answers, three major obstacles have been highlighted. First, there is a clear lack of demand from real estate developers in a context where there is no lifecycle performance regulation yet. Second, the high cost of the use of LCPA methods disqualifies their use at early design, where the financial risk is at its highest level. Last, there are collaboration issues between architects and engineers, decreasing the LCPA benefits. In addition to previous surveys focusing on the scientific issues of the LCA methodology only, these results provide a unique user-centred knowledge for LCPA software and method developers.

1. Introduction The Architecture, Engineering, and Construction (AEC) industry is fully impacted by the successive international agreements on climate change mitigation. Indeed, the built environment represents 33% of the world’s emissions (UNEP, 2009a, 2009b). On the European scale, all new buildings starting from 2020 will have to be nearly zero energy (EU - EPBD, 2010), and countries like France have begun to implement Life-Cycle targets (DHUP, 2016) to consider the embodied environmental impacts which are becoming as predominant as the operational impacts (Hoxha et al., 2016). In this context, the complexity of the design process will dramatically increase, as every building component and system will be considered in the performance assessment. Many researchers are already actively involved in the development of new Building Performance Simulation (BPS) tools at early design stages (Østergård, Jensen, & Maagaard, 2016), where the implementation of environmental assessments remains a challenge so far (Azzouz,

Borchers, Moreira, & Mavrogianni, 2017; Hamedani & Smith, 2015), but should have the largest benefits on the design (Häkkinen, Kuittinen, Ruuska, & Jung, 2015; Jusselme, Rey, & Andersen, 2017). The development of new methods should carefully integrate a full understanding of user context. This is specifically the purpose of the User-Centred Design (UCD), developed in the 1980s by Donald Norman’s research laboratory at the University of California San Diego (Abras, MaloneyKrichmar, & Preece, 2004). Although UCD and the concept of usability are widely used and developed within the Human-Computer Interaction research field, BPS tools are rarely developed based on such an approach to the best knowledge of the authors. As a consequence, existing early design tools are not really used by architects, and did not meet their specific requirements (Attia & De Herde, 2011; Attia, Hensen, Beltrán, & Herde, 2012; Weytjens, Attia, Verbeeck, & Herde, 2011). Bleil De Souza and co-workers summarized the situation very clearly:

• “Current research in the field tends to be quite unilateral and seems to be

Abbreviations: AEC, Architecture, Engineering, and Construction; BIM, Building Information Modelling field; BPS, Building Performance Simulation; EU, European Union; HCI, Human–Computer Interaction; LCA, Life-Cycle Assessments; LCP, life-cycle performance; LCPA, life-cycle performance assessment; UCD, User-Centred Design ⁎ Corresponding author at: Building 2050 – EPFL, smart living lab, Passage du Cardinal 13B, Case postale 487, CH-1700 Fribourg, Switzerland. E-mail address: [email protected] (T. Jusselme). Received 23 January 2019; Received in revised form 17 September 2019; Accepted 6 October 2019 Available online 14 October 2019 2210-6707/ © 2019 Elsevier Ltd. All rights reserved.

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b Environmental LCA Tools for Buildings (e.g. Elodie (CSTB, 2019), eTooL (eTool, 2019), etc.); c Environmental Assessment Frameworks and Rating Systems (e.g. BREEAM, LEED, etc.); d Environmental Guidelines or Checklists; e Environmental Product Declarations, Catalogues, Certifications and Labels.

based on interpretations of what the building physics/simulationists community assumes the building designer needs. As this community lacks a comprehensive understanding on the paradigms of knowledge and praxis of the building designer, it tends to be quite limited in terms of their propositions.” (Bleil de Souza, 2012) “There is a lack of knowledge in BPS on user profiling, and on understanding user experience, user goals and associated task analysis.”(Tucker & de Souza, 2016)

Among them, one can distinguish active tools with software that allow the user to calculate and evaluate different scenarios (a and b), and that delivers a quantitative assessment. On the other hand, there are passive tools (c, d and e) who do not interact with the user but support the design with straightforward and qualitative recommendations. In research and engineering activities, it is commonly accepted that LCA tools (b) are the most comprehensive and helpful to support the design (Saunders et al., 2013; Sibiude et al., 2014). Thus, among these 5 categories, LCA tools (b) is generally the one that is meant when discussing about LCA. That is why LCPA is the term that will be used in the frame of this research, to enlarge the survey to all tools and methods (a–e) used in the AEC industry, and not only LCA.

This is even truer when focusing on life-cycle performance assessment (LCPA) tools where no usability context analysis has been conducted to the author’s knowledge. Thus, as it will be further detailed in section 1.3, there is a clear decorrelation between the increasing research activity on building and Life-Cycle Assessments (LCA), and on the other hand, the limited available studies on the practitioner’s context when it comes to assess the environmental footprint of their project. This research aims to better understand the profile, needs and requirements of potential users of LCPA tools and methods, which is the first step towards a UCD approach, while previous surveys were mostly centred on the scientific issues of the LCA. The work has been conducted in three successive steps. First, a literature review on the current developments in terms of LCPA and usability framed the context and objectives of the present research. Second, the methodology to collect data about the usability context of LCPA was set up. Finally, the collected data were analysed and discussed, highlighting key recommendations for the LCPA usability.

2.1.2. Limitations and new approaches The research activities in building and LCA increase year after year, but many challenges still need to be addressed. Thanks to the literature (Anand & Amor, 2017; Jusselme et al., 2018a), the following limitations can be highlighted in a non-exhaustive list:

2. Literature review The purpose of this first section is to better understand the two main subjects of this research, on the one hand, the LCPA, and on the other hand, the usability concept. In the end, a literature review is performed to identify potential research that already has cross usability and LCPA. 2.1. Life-cycle performance assessment

○ Building life-cycle assessments are time-consuming; ○ They need a high resolution of detail, unavailable at early design stages; ○ Boundaries and scopes are specific; results are non-reproducible; ○ The service life of a building is not reliable; ○ Due to the high number of components, the data collection leads to high uncertainties.

Regarding the two first points, namely the time-consuming and resolution detail issues, recent developments proposed two promising approaches. The first one is the real-time LCPA, developed by Hollberg, Lichtenheld, Klüber, and Ruth (2017) and Basbagill, Flager, and Lepech (2017). It provides quasi-real-time feedback thanks to a parametric approach and simplified assessment algorithms. As a result, you can modify a drawing, and have a direct consequence on the building lifecycle performance. The Building Information Modelling (BIM) process provides the necessary inputs to LCA methods and allows this real-time assessment. The second promising approach is the LCA based datadriven method (Jusselme et al., 2016, 2017). It can use refined calculation algorithms and it allows for an exploration of the design space by assessing thousands of variants of an initial project using high computing power. The success of both techniques strongly depends on interactions with the users and requires a better understanding of the user behaviours and requirements.

2.1.1. LCPA methods and tools Thanks to the ISO 14040-43 (1997–2000), the methodology of lifecycle assessment has been standardized, allowing the method to be disseminated with four major steps: defining the goal and scope, creating the life-cycle inventory, assessing the impact and interpreting the results. Nowadays, life-cycle performance (LCP) targets integrate most of the green building certification systems (e.g. LEED, BREEAM, HQE) and are about to be mandatory at horizon 2020 in some countries like France. Indeed, the European Union decided in 2010 to target a near Zero Energy Building standard for all its new buildings (EU - EPBD, 2010). With such an energy performance level, life-cycle thinking is more than recommended as most of the energy impact of the building will be shifted from the use phase to the other phases of the building lifecycle. Supported by these trends, the research community develops methodologies and tools to increase the LCPA robustness and usability. Latest research scopes include building refurbishments (Nicolae & George-Vlad, 2015), prefabricated buildings (Bonamente & Cotana, 2015), urban scale assessment (Drouilles et al., 2018), building stocks (Zhang & Wang, 2015), certification systems (Roh, Tae, Suk, Ford, & Shin, 2016), to name a few. Various instruments have been developed to assess the building lifecycle performance. According to Haapio and Viitaniemi and based on the IEA Annex 31 project “Energy-related environmental impact of buildings” (Haapio & Viitaniemi, 2008), assessment tools can be categorized into five categories:

2.2. Usability definition Usability is defined by ISO 9241-11 as the following: “extent to which a system, product or service can be used by specified users to achieve specified goals with effectiveness, efficiency and satisfaction in a specified context of use” (ISO, 2018). This norm enables one to qualify a product by measuring usability through user performance and satisfaction. The User-Centred Design (UCD) approach is specifically focusing on the integration of the usability requirements into the design process. A simple search on the Scopus website (‘Scopus—Document search results’, 2017) with the “human-centred design” keywords demonstrates that this field has an active research community that already

a a Energy Modelling software (e.g. energy plus (EnergyPlus, 2019), Trnsys (TRNSYS, 2019), etc.); 2

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participants, it is also the oldest one (Hofstetter & Mettier, 2003). It focused on the US population, which has downloaded BEES 2.0, an LCA software targeting the US building industry. Another survey with a large population (Pizzol et al., 2016) was also centred on normalization and weighting in the LCA methodology. Sibiude and co-authors concentrated the survey on the interpretation and reporting steps of the LCA methodology, proposing to LCA tool developers some recommendations about the aggregation system that should be implemented (Sibiude et al., 2014). Cooper and Fava investigate the benefits and barriers of LCA methods and software (Cooper & Fava, 2006). Other studies analyse deeply the definition and characteristics of the user. Han and Srebric made the relationship between the respondents’ background and the use of BPS or LCA. According to them, there is a positive correlation to the company size and a negative one to the respondent experience. They also discover that LCA is rarely used by professionals compared to energy simulations (Han & Srebric, 2015). Similarly, Olinzock et al. (2015) found a clear high degree of interest regarding sustainability issues from the AEC industry. However, only 12% of the respondents were using LCA on the majority of their project. In contrast, using LCA seems to be beneficial for the project, contradicting its low practice. For Olinzock et al., the lack of client demand is one of the main barriers of LCA practice. While the first surveys cited previously were quantitative and targeting a large population, two other studies have been found with a qualitative approach. The first one (Saunders et al., 2013) applied the focus group technique, which allows in-depth discussion with qualitative data emphasizing open discussions. This study focuses on the main barriers and benefits of LCA methods. Complexity, time, and accuracy were highlighted for the barriers, and “providing information about environmental impacts” for the main benefits. The authors also noticed the necessity to combine their research with a national survey with a larger sample size. The second study (Schlanbusch et al., 2016) limited their survey to the Nordic countries, focusing mainly on gaps and issues within the LCA methodology. All these publications are listed and qualified in Table 1, according to the context of use description items of the ISO 9241-210, their main geographical scope, and survey participant numbers. As a conclusion of this literature review, one should note that a large majority of previous studies have been performed in the US and only two within the EU boundaries with a limited number of participants. Second, there is not yet a comprehensive survey according to the UCD fundamentals, including all the knowledge needed to start a UCD approach. Moreover, if some of the studies mentioned the software developer guidance as one of the main objectives, the UCD methodology was never applied or cited by the authors. Third, the lack of knowledge is particularly true for the technical, physical and social environment, and more generally for the context of use of LCPA methodology and tools. Indeed, most of the surveys were focusing on methodological issues rather than the design process, or the users’ needs and environment. None of the following questions has been answered yet when it comes to the use of LCPA tools:

has around 6919 registered papers, publishing currently almost 700 papers per year with a first recorded paper written in 1974. For a better understanding of UCD in practice, ISO 9241-210 norm (ISO, 2010) provides requirements and recommendations. According to the norm, UCD encompasses: a b c d

the the the the

understanding of the context of use, specification of the user requirements, production of design solutions, and usability assessment of these solutions.

Iterations between b, c and d allow continuous improvement of the design. The purpose of this paper is to collect information that will enable LCPA developers to start a UCD approach. Then the research will be focused on the context of use (a) defining the user requirements (b). According to the ISO 9241-210 recommendations, the context of use description should include the following:

• The definition of different users or stakeholder groups of users, • The characteristics of the users, • The goals and tasks of the users, • The technical, physical and social environment. There are many methods to collect this information. In their work, Rekha Devi and co-authors consider twelve different techniques (Rekha Devi, Sen, & Hemachandran, 2012), including focus group, interviews, surveys, task analysis, etc. A comparison between them allows choosing the good one according to the situation. Different publications in the field of HCI propose guidance for usability context analysis (Bevan & Macleod, 1994; Thomas & Bevan, 1996). 2.3. Highlighting the research gap If usability is a specific field of HCI, one can notice that there are very few research materials available when it comes to the LCPA research domain. Thus, considering the novelty of this approach and the lack of research material, BPS works focusing only on operational energy have also been considered in this literature review. In addition, as LCPA aims at supporting the design process, an overview of the early design stage context has been done. 2.3.1. Usability context of LCPA This section summarizes a literature review of the LCPA practice within the construction industry. It has been limited to the past fifteen years, considering that older studies would not have been relevant nowadays according to the major improvements performed in terms of methodology and software these past years. Previous surveys were mostly centred on the scientific issues of the LCA methodology rather than being user-centred. Indeed, the biggest survey targeted a better understanding of the user wishes in terms of environmental indicators and impact aggregation methodology, rather than the decision-making process, and context of use. With 566 survey Table 1 A literature review of previous LCPA practice surveys. References

Cooper and Fava (2006)

Han and Srebric (2015)

Hofstetter and Mettier (2003)

Olinzock et al. (2015)

Definition of the different users The characteristics of the users The goals and tasks of the users The technical, physical and social environment Main geographical scope Survey participants

x x

x x

x x x

x x x



US 566

US 250

World 216

US 37

North America 65

US 96


Pizzol et al. (2016)

Saunders et al. (2013)

Schlanbusch et al. (2016)

Sibiude et al. (2014)


x x

x x x

Nordic countries 57

France 121

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2.3.3. Design process According to the RIBA plan of work, the earliest phase of the design is the concept design that builds up first project strategies with structural design, building systems proposals and first cost information (Sinclair, 2013). Accordingly, the level of detail available about the project is very low and does not allow a precise analysis of the life-cycle performance of the project (Malmqvist et al., 2011). This is a common issue every assessment method has to face at early design stages (Attia et al., 2012; Riether & Butler, 2008) and that might explain the lack of usability of BPS. Moreover, the design process is iterative between the design brief and the architectural proposition (Prost, 1992). It is characterized by a loop where solutions are first generated, then analysed according to the design brief objectives, and third, implemented into the project according to their compliance with these objectives. All these iterations are time-consuming, around five to seven weeks for each. As a result, architects and engineers spent more than half of their time managing project information rather than executing, reasoning and specifying the project (Flager & Haymaker, 2009). However, this survey was performed on fifty professionals from a single company from which only 10% were architects. Regarding the design parameters, previous studies (Morbitzer, Strachan, Spires, Cafferty, & Webster, 2001) attempted to classify them, matching BPS inputs and designers’ concerns according to the design stages.

Fig. 1. Comparison between LCA practice surveys (in brackets) and the evolution of the scientific articles (black line) published since 2003 and related to Building LCA. Information obtained from Scopus for the keywords “LCA + building”.

• What are the relationships between LPCA tool users? • When and how are users questioning the life-cycle performance of their project? • How much time do they have/need to perform an LCPA analysis?

2.3.4. The need for a survey Many researchers point out the mismatch between designers’ requirements at the early design stage, and BPS tools available on the market. This gap is specifically important for architects, who are not satisfied with current tools and methods, generally developed by engineers. First usability assessments have been performed on BPS tools, as a post-design check-up. However, the first step of a UCD approach, namely the understanding of the context of use, has never been done in the BPS field, even if UCD is widely recognized as an important research activity in the frame of Human-Machine Interaction. To fill this gap, a usability context analysis has to be driven, and it is specifically the purpose of this survey.

It is also worth to notice that these practice surveys represent a very small minority of the research conducted on LCA and buildings, as it is illustrated in Fig. 1. Indeed, upon 2346 scientific articles published since 2003, and identified by the website, only the eight one illustrated in Table 1 were focused on understanding the LCA context of use. Although, they are fundamental inputs for increasing the LCA usability. To increase the state of the art insights, the following section will broaden the scope of analysis by including also research on BPS tools focusing only on the energy use of buildings. 2.3.2. Usability context of energy assessment tools Several studies point also to the limited use of BPS in building practice, specifically by architects and at early design phases, because of their low usability (Attia, Beltrán, De Herde, & Hensen, 2009; Hong, Chou, & Bong, 2000). Moreover, extending the literature review to BPS tools focusing only on operational energy consumption helped to better understand the social context of BPS users within the design process. One can learn thanks to Alsaadani and Souza the social collaboration between BPS consultants and Architects (Alsaadani & Bleil De Souza, 2016; Alsaadani & Souza, 2017). They point to a negative perception of BPS tools by Architects, probably due to a misperception of the BPS, understood more as compliance decision support than a source of creativity. They also notice that their professional trust as well as communication between them qualified as neutral, and not efficient. However, many underlying questions are listed with no answers so far, highlighting the necessity to consider the human dimension of collaboration as important as the technical simulation challenges. Regarding the BPS context of use, the quantitative objectives request new players as BPS consultants in the design teams, obliging architects to decrease their control on the project if they cannot quantify themselves, and creating tensions in the collaboration. It is also mentioned that BPS tends to be performed later in the design process because of the client’s role that under evaluates the BPS importance, limits the engineering fees, or has a lack of interest. Tucker and de Souza (Tucker & de Souza, 2016) state that HCI techniques have the potential to develop more usable BPS interfaces, but point out that there is not enough knowledge so far in BPS user behaviour, goals and profiles. Generally, very few BPS tools seem to be appropriate for architects, as they are unable so far to guide and assist them to perform energy simulations in the design process (Bambardekar & Poerschke, 2009).

3. Content of the survey 3.1. Objectives The three main objectives of this survey are the following. First, the overall purpose is to offer to LCPA developers a comprehensive and context-oriented study, guiding them towards more usable tools. Second, the ambition of this survey is to target the European level to be representative enough of a large design community. It will also complete the state of the art where a large majority of previous studies were performed in the US. Third, the goal is to target specifically early design phases, as the state of the art mentions that integration of life-cycle performance targets is crucial and that current BPS tools seem to be particularly ineffective at this stage. At early design, three different practitioners are targeted (Zabalza Bribián, Aranda Usón, & Scarpellini, 2009): architects, engineers/consultants and real estate developers. 3.2. Methodology In 2001, Maguire described and compared six different context-ofuse methods (Maguire, 2001). Among them, the survey of existing users is particularly suitable for the context and objectives of this article. Indeed, it is the only one that allows for reaching a diverse and difficultto-access population, in this case at the EU scale and with different professional profiles. It consists of a set of written questions to a sample population of users. It also pointed out that such a survey is timeconsuming. Among different recommendations, the survey might be kept as short as possible, with open and closed questions. Generally, this survey uses Likert-scale to catch the level of intensity 4

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of the respondents according to a specific question, with high efficiency when it comes to analysing the data. When Likert-scale was not appropriate, multiple choice questions have been used, giving always the possibility to the respondent to choose the “other” choice and then precise an answer that would not have been proposed by the survey. The Survey Monkey software was used to set up an online questionnaire. The closed questions were framed to make answers easy with a pull-down menu encompassing categorical data (e.g. country), ordinal data with Likert scales (e.g. not at all satisfied to very satisfied), and interval data (e.g. age: 35–44). Once a first survey version was completed and according to the rule of five (Hubbard, 2010), a test on five participants was performed to check the understanding and the length of the questionnaire. After integrating the feedback of these first participants, the questionnaire was spread to more than 33’000 European people from the AEC community. At the EU level and to the best knowledge of the authors, it is impossible to evaluate the actual size of the LCPA tool users’ community so as to define a target number of respondents. Thus, the targeted population size has been defined according to the previous best practices and set to 500 respondents. Indeed, the largest survey so far was conducted fifteen years ago with 566 participants in the US (Hofstetter & Mettier, 2003). The answers were collected after two successive reminders and a four-month period between 06/21/2017 and 11/08/ 2017. In the end, only the respondents fitting with the scope of the survey have been kept, that is to say, the one working as architects, engineers/consultants and real estate developers within the EU boundaries. Regarding the data analysis, bar charts and box plots with average and deviations are used to highlight the survey results. To reinforce the analysis, and considering that the collected data are mostly categorical, a Chi-square test (McHugh, 2013) for independence has been performed additionally to show the bivariate associations. To determine whether the variables are independent, the p-value of the Chi-square test has been compared to the significance level considered to be 0.05. In other words, when the P-value is below this threshold, the variables are considered to be statistically associated. When calculated, this Pvalue is noticed in the legend of the related graphics. 3.3. Survey questions Fig. 2. Presentation of the overall survey. The parts interpreted in this paper are the ones within the dashed perimeters. The numbers in the rectangular grey boxes correspond to the number of participants that reached a particular point of the survey.

As this survey had an explicit focus on the context of use, it was set to answer the following overarching questions: - What is the purpose-of-use that LCPA methods and tools have to address? Here the point is to collect users’ feedback about their needs and their vision of what objectives the methods should achieve. - What is the audience that will benefit from these methods and tools? - What is the context of use? What situation induces the method’s needs?

A first conference paper has been published by the authors (Jusselme, Rey, & Andersen, 2018) about the current use of LCPA by practitioners in terms of LCPA tools and methods. The present paper focuses more specifically on the social context and interactions, through the issues highlighted by the article boundaries in Fig. 2. 4. Results

These three major questions have been detailed and subdivided based on the understanding of LCPA specificities, on the previous literature review, and on the literature recommendations about usability context analysis (Thomas & Bevan, 1996). Forty questions came out of this work, represented in Fig. 2. They have been reordered to be asked in a logical way to be answered by the participants. The questions were grouped by theme, starting with demographic questions. The specific list of questions (cf. Appendix A) was inspired by ISO 9241-210 and previous research (Maguire, 2001; Thomas & Bevan, 1996). As the EU scale has been targeted, the questions were written in English. No translation in other languages has been proposed to avoid a different understanding of the questions according to the languages. Multiple choices were proposed and a random function was used to change their order and thus lower the influence of the answer positions.

At the end of the survey campaign, 495 participants had filled out the survey, with a completion rate of 71% and an average duration of response of seven minutes. Thanks to Fig. 2 it is possible to know how many participants fulfilled each part of the survey. 414 participants were in the scope of the survey, within the targeted population of architects, engineers/consultants and real estate developers, and within geographical Europe. 4.1. Sociological profile of the life-cycle performance assessor 4.1.1. A pro-active community One of the ambitions of this study was to target the European scale, which has been successful with respondents working in 26 different EU 5

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Fig. 4. Awareness of the practitioners, according to their working countries, about the future nearly-zero energy building regulation in Europe, out of 264 answers.

themselves. To test the practitioners about future regulations, a question were asked about the future EU regulation in which all new buildings starting from 2020 will have to be nearly zero energy (EU - EPBD, 2010). On average, 50% of the respondents were aware of this future regulation, which is a high rate, but large disparities were noticed between countries. Among the seven countries that have the highest number of answers, the awareness rate varies from 90% in Italy to 36% in the UK (Fig. 4). Additionally, with a P-value of 0.003, the Chi-Square test demonstrates a significant influence of the country variable on the EU regulation awareness. 4.1.2. A high interest in life-cycle performance One of the most surprising results of the survey was the very high level of consideration of the life-cycle performance by the respondents. According to Fig. 5, 59% of the practitioners claimed to consider it often or very often. Moreover, among the only 4% that never consider life-cycle performance, almost everyone agreed that they will have to in the future. The main reason for those that answered “never” was the absence of the client’s requirement regarding this type of analysis. This enthusiasm might be explained by the fact that the environmental constraints are largely perceived as an opportunity by more than 70% of the respondents, as shown in Fig. 6. It is rarely a threat (7%) and might be a source of innovation and creativity. The answers to these two questions highlight a very high interest by architects and engineers regarding the environmental constraints, and a fundamental wish to integrate this performance criterion within their design process.

Fig. 3. Working countries of the 414 Engineers, Architects, and Real Estate Developers that answered the survey.

countries. However, 80% of the participants were located in 7 countries only, namely, in decreasing order: the UK, France, Switzerland, Germany, Italy, Spain and the Netherlands, as illustrated by Fig. 3. Regarding gender, females are clearly a minority in this population, with only 18% of the participants. It is reflecting the current situation of architects in Europe to have such a disproportion between males and females, looking at the French (25%) and UK (21%) ratios (Fulcher, n.d.; ‘La profession en chiffres’, 2006). Among the 414 participants that fulfilled the survey criteria, 82% of them were architects, 13% were Engineers, and 4% were Real Estate Developers. This is fully in line with the objectives of this survey that targeted the early design stage, and where the design team is often reduced to the architect competences only. Indeed, in this survey, one architect out of two does not work with building environmental consultants at conceptual design stages. Also, very few participants were Real Estate Developers. Even if they were not specifically targeted by the study, they did not feel concerned by the life-cycle performance issue. Actually, only 41% of the participants have to consider life-cycle performance because of the client’s requirements. On the opposite, 77% of the respondents analyse the life-cycle performance of building designs because it is part of the best practices of their company. This was a multiple-choice question allowing cumulative answers. It certainly means that dealing with LCPA during the design process is first a proactive behaviour of the design team, before being a request of the client. The survey also reveals that 74% of the respondents consider the environmental performance of their building project as fairly critical (41%), critical (24%) or very critical (9%) compared to their other constraints. Therefore, even if there is low demand from the clients, the pro-active behaviour of the respondents must lie in the recognition of environmental performance as one of the success factors of a building project. The other stress sources might come from the civil society, the end users, or the environmental convictions of the designers

4.2. Life-cycle performance assessment and social interactions When it comes to life-cycle performance assessment, 46% of the respondents are working with external consultants, and 16% with an

Fig. 5. Consideration of life-cycle performance by practitioners, out of 408 answers. 6

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Fig. 6. Perception of environmental regulations by practitioners, out of 264 answers.

internal consultant. Thus, it leads in many cases to interdisciplinary collaborations between people with different skills, backgrounds and languages. A full section of the survey has been dedicated to analysing these social interactions between architects and engineers. The same questions to each of these populations were asked and adapted highlighting potential asymmetries in their answers. The following figures show how engineers understand architects, and vice-versa. The first question was about the collaboration rate between them at the conceptual design stage. Fig. 7 highlights that 74% of the engineers are used to collaborate at early design with architects. They are only 54% on the architect side. This 20% difference should be explained by the holistic approach that has to develop an architect, which does not have the time and the budget to involve a specialist in LCPA for every project. On the contrary, an engineer as a specialist should have LCPA as its only objective and should be interested in collaborating as early as possible in the design process. Regarding the satisfaction they have to work together, a question targets the ability architects have to integrate the added value of environmental consultant and vice-versa. Again, an asymmetry is observed in the answers with 34% of the engineers agreeing that the architect’s ability to integrate their added value was poor or very poor, while 15% of the architects only were sharing the same position about engineers (Fig. 8). The P-value of 0.001 of the Chi-square test validates the dependence of these variables. There is also a significant difference in the answers when judging their ability to mutually understand their constraints. Indeed, Fig. 9 highlights that 34% of the engineers are not or not at all satisfied, instead of 21% or the architects. Again, the Pvalue of 0.035 of the Chi-square test confirms this statement. Finally, a specific question has been asked to determine the architects’ and engineers’ opinions about the responsibility of integrating the life-cycle objectives into the design process (Fig. 10). Overall, 74% of the survey participants agreed that both architects and engineers should be concerned. This demonstrates a strong awareness of practitioners of the collaboration necessity when dealing with environmental issues. It is also interesting to notice that the rest of the respondents were clearly split into two groups: Architects convinced that it is their own responsibility only, and Engineers having the same behaviour. It might signify that this population is clearly not identifying any collaboration

Fig. 8. Architects’ and engineers’ ability to integrate each other’ added value, out of the answers of 227 architects and 35 engineers (P-value = 0.001).

Fig. 9. Architects’ and engineers’ ability to understand each other and their constraints, out of the answers of 227 architects and 35 engineers (Pvalue = 0.035).

Fig. 10. Architects’ and Engineers’ opinions about the life-cycle performance responsibility within the design process, out of the answers of 222 Architects and 34 Engineers (P-value = 0.001). Fig. 7. Collaboration rate between architects and engineers at the conceptual design stage, out of 227 architects and 35 engineers (P-value = 0.03). 7

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Fig. 11. Computer software penetration according to the company size, out of 414 and 411 (respective) answers (P-value = 0.99).

issue on this subject, and want to manage this alone. 4.3. The mismatch between life-cycle assessment tools and the early design process 4.3.1. A low software penetration “Do you consider life-cycle performance?” is a broad question that let the participant answer with different interpretations of what lifecycle performance may be. Indeed, practitioners use a large variety of tools and methods to assess this life-cycle performance and only 27% among them are using LCA software (Jusselme et al., 2018b). This is a very low rate, considering that the complexity of a life-cycle assessment decreases the efficiency of qualitative approaches (e.g., guidelines or technical references). This penetration rate has been analysed according to two discrimination factors: the company size and its R&D activities. In Fig. 11, it can be noticed that the companies with LCPA software are slightly under-represented below 11 employees, and overrepresented above. Also in Fig. 12, companies involved in R&D activities have an equipment rate with an LCA software 7% higher than the others: 59% instead of 52%. However, the Chi-square test did not allow concluding to any significant dependence between these variables. Fig. 13. Length of the conceptual design phase in weeks, out of 264 answers.

Thus, using LCA software is not a common practice for the respondents, and if one can notice small variations in the answers, it is not possible to observe different behaviours according to the company competencies and size. 4.3.2. A high cost of use One of the goals of this survey was to define the cost of use of a lifecycle performance assessment. To that end, the survey characterized first the time spent during conceptual design stages thanks to Fig. 13. This figure is a Tukey boxplot highlighting groups of design lengths through their quartiles. Despite extreme high values, it shows that the conceptual design phases take less than 17 weeks for 75% of the population, and 12 weeks on average for a building. When looking to the median of the answers, the length is even shorter with 8 weeks. During this time, designers produce on average three different alternatives, which confirms their necessity to develop an iterative design process

Fig. 12. Computer software penetration according to the R&D activities, out of 414 and 411 (respective) answers (P-value = 0.91). 8

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Fig. 14. Number of design alternatives of the conceptual design phase, out of 264 answers.

and explore different variants of their projects. As can be seen in Fig. 14, Architects and Engineers agreed on the same number of alternatives, respectively 3,3 or 3,2 on average, or 3 for the median. Some participants commented that this question was hard to answer, as it also depends on the context of the project, but this answer could be considered as an order of magnitude, robust enough for the following analysis. Fig. 15 highlights the time spent to assess the life-cycle performance of a design alternative. It is on average 24 h, i.e., around 3 days of work. Furthermore, the global wish is to extend this length to 28 h, which means that the current time allotted to the assessment is not enough. Looking deeper into the data, the tools and methods used are a strong discrimination factor as they change this average length from 18 h for the one using rules of thumb to 34 h for the one using computer software. This analysis seems coherent with quantitative tools to be more time consuming, followed by external or internal consultants, which need to be provided by the project details, and support in their result analysis. Finally, the quickest methods are the qualitative ones, which are also the most highly used by the respondents according to (Jusselme et al., 2018b): regulation and norms (used by 43%), design guidelines (43%), technical and architectural references (61%), and rules of thumb (33%). In comparison, computer software is only used by 27% of the respondents. In synthesis, a practitioner using LCA software to assess the lifecycle performance of its building project at the conceptual design stage will need 33.7 h (Fig. 16) on average for each design alternative. As practitioners usually design three alternatives at that stage, the

Fig. 15. Lengths of a life-cycle performance assessment, out of 322 answers.

theoretical assessment length of the three alternatives growth up to 100 h, that is to say, two and half weeks full time for one person, mostly without any demand from the client, and for a design phase duration of 2 to 3 months. 5. Discussions Literature suggests that previous surveys targeting practitioners in the field of LCA were usually limiting their participant sample below 250. With 495 answers, this survey goes far beyond previous studies in terms of sample size. However, the representativeness of the sample has not been demonstrated, as its distribution has not been compared to the targeted population. Indeed, the targeted population was architects, engineers, and real estate developers at the EU level, but no global database identifying population by country was identified. In terms of language, the survey was proposed in English only, to prevent any bias in the translation of the questions. On the other hand, it might have limited the participants to the ones knowing this language, which distribution varies from one country to another. In addition, it is supposed that there might be a bias in the sample of participants, as the willingness to answer this survey might be higher for those already interested in LCP than others ignoring this field. Therefore, one can assume that the results are slightly optimistic in 9

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embedded design alternatives. It really strengthens the point that the cost of use of LCA software is far too expensive. As an example, if the following are considered:

• a daily consultancy fee to be 800€ per day as a European average, • an LCA with software requires almost 4 days (Fig. 16), • an LCA should be done for each of the three alternatives that are proposed on average (Fig. 14).

Thus, the cost of use represents roughly 10,000€ only for the early design stage. These elements let us speculate that LCA is still not a client’s requirements, and even if there is high interest by practitioners, this amount limits the use of LCA into practice. This is specifically true at the early design phase, which is most of the time under the form of an architectural competition with a very limited budget, or even no budget sometimes. It is interesting to notice that in comparison to the cost of use, the cost of the software itself does not seem to be an issue, as no significant influence of the company size to software penetration (Fig. 11) has been observed. This finding is in contradiction with the positive correlation to the company size that was noticed by Han and Srebric (Han & Srebric, 2015). Moreover, the cost of use of LCPA techniques seems to be of major importance, as even qualitative approaches like “rules of thumb” or “technical and architectural references” fail to be quick and are probably hardly usable as they still represent 6000€ for the early design phase (assuming the same hypotheses). 6. Findings and recommendations Fig. 16. Lengths of a life-cycle performance assessment, according to different tools and methods, out of 322 answers.

This research identifies a real willingness of engineers and architects to use LCPA while there is a major gap between their context of use, and the method’s abilities to fit these specific constraints, making them ineffective. The study reveals that this LCPA user community is proactive and considers environmental constraints as an opportunity. They use life cycle thinking as a best practice that they have to follow. Finally, yet importantly, they are largely convinced by the integrated design principle, considering that life-cycle performance should be the responsibility of both engineers and architects, who have to tackle this issue early in the design process. However, it is clear for the authors that the daily practice of LCPA does not reflect this enthusiasm, as most of the respondents were using qualitative approaches with a low software penetration rate of 27%. Then, the quantitative life-cycle performance assessment is facing major obstacles, preventing current software from being widely used, specifically for the early design phase. Upon them, one can cite:

favour of LCPA practices. Olinzock et al. (2015) noticed a large gap between the sustainability interest of the AEC industry and the real LCA practice. They estimate the practitioners using LCA on a majority of their project at 12%, even if everyone recognized it as beneficial. In comparison, 60% of the respondents considered life-cycle performance often or very often, while 27% of the respondents were using LCA software. There is still a gap, but it tends to be smaller over the years than the Olinzock et al. study, which was realized in 2012 and targeted the US only. It is possible to compare the answers to the ones that have been already provided by the BPS community, even if they were mainly focusing on energy assessment instead of LCPA. Regarding the relationships between the design stakeholders, Alsaadani and Bleil De Souza (2016) found similar results regarding the lack of interest of building clients for BPS. They conclude there is a significant lack of trust in professional competence and commitment between architects and consultants that might affect the collaboration quality. This new survey brings a better understanding of this trust issue, with an asymmetry between architect and engineer judgments. Indeed the survey demonstrates that engineers feel much more unsatisfied than architects in their collaboration (Figs. 8 and 9). More specifically, one-third of engineers find the architect’s ability to integrate their added value into the design and to understand their constraints to be poor. This feeling might be directly linked to the complexity of the LCA, the mismatch of the resolutions detail, and the slowness of the tools and methods. However, these results have to be carefully considered since they rely on a significant difference that exists between the two samples of architects and engineers, being respectively 340 and 54. In 2007, a survey on a single office population pointed out that it takes more than a month for designers to complete a design iteration between the stakeholders, with no more than three of these design cycles at the conceptual design phase (Flager, Welle, Bansal, Soremekun, & Haymaker, 2009). It is fully consistent with this study where the average early design phase lasts three months and has three

• A clear lack ofLCP-based requirements from the clients. Thus, the


market demand is very low, contrasting with the scientific community warnings about climate change, and the engineer and architect’s empathy. However, future EU regulations about greenhouse gases mitigation might represent very powerful market traction. A high cost of use that makes LCPA tools probably unusable at early design stages. In fact, the cost of use is much higher than the cost of the LCA software themselves. Indeed, the engineering fees estimated on average at 10,000€ at the early design stage is a strong barrier for real estate developers to engage LCA expenses at a financially risky stage. Major issues in the integrated design process, with an asymmetric perception of the social interactions induced by LCPA between architects and engineers. Collaborations at conceptual design stages are a necessity for 74% of the participants. However, architects do not involve engineers in more than 54% of their projects at the conceptual design stage. Also, one-third of engineers are frustrated about this relationship, even if they are more used working with architects at early design stages. It seems that engineers have

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2018a) seems to be very promising. Indeed, this method proposes an exploration of the architectural and technical possibilities (i.e. the design space) according to a performance threshold, rather than an evaluation of the schematic design as most of the LCA input would be hypotheses reducing the relevance of the LCA results. Thus, combining higher output benefits of exploration methods with a lower input collection length with BIM methods should lead to considerably higher LCPA usability. Finally, it is necessary to propose mixed approaches when it comes to communicating between architects and engineers about the LCPA results. Both quantitative and qualitative approaches need to be proposed to make a bridge between the necessity of engineers to verify the compliance of conceptual design with numerical thresholds (e.g. kgCO2/m²) and the necessity of architects to understand how results impact the design in terms of space, materiality, light, etc. 7. Conclusions This paper provides a description of the current practice and context of use of life-cycle performance assessment. Previous researchers were able to highlight the technical needs of LCPA practitioners but they never addressed either the context of use or the European scale. However, this context of use is considered as the first step of major importance in a User-Centred Design approach, following the ISO 9241 norm. Hence, the goal was to fill this gap thanks to an extensive online survey, whose results provide evidence basis towards more targeted LCPA development and an increase of their usability. The research findings highlight a decorrelation between (a) the high practitioner’s willingness to consider environmental constraints in their practice, and (b) the low current use of LCPA software. This situation brings up socio-technological issues that should be addressed at the same time. From a sociological point of view, a first barrier is the absence of client’s incentives, a paradoxical situation in a European society where climate change is nowadays a daily discussion for everyone. A second sociological obstacle is the specificities between architects and engineers’ culture, language, and even work methodology whose discrepancies bear the risk of decreasing the integrated design efficiency. From a technological point of view, the cost of use of LCPA methods is the major issue. This creates the necessity to develop new techniques decreasing the input collection efforts while increasing in the same time the design support abilities in the specific context of early design stages, where projects have a very low detail level. To that end, new approaches should be investigated, such as exploration methods that, unlike assessment methods, are leveraged by design uncertainties. If this research clarifies the LCPA context of use and the current practices, it needs to be complemented by a better understanding on how LCPA results affect engineer’s and architect’s professional activities, i.e. to which extend LCPA results may influence the design process. To that end, the next research step of the co-authors will specifically focus on developing an LCPA method focusing on the early design context to match the requirements emerging from this survey, and most of all, to evaluate the impact of this new method on practice.

Fig. 17. Mechanisms decreasing the use and the usability of life-cycle performance assessment methods at the early design stage.

difficulties to transfer their knowledge into the design process, led by architects that already have to face plenty of other constraints, and that might have some difficulties to understand the engineer technical language when it comes to the complexity of the LCPA studies. The combination of these three major obstacles might annihilate the practitioner’s willingness to use LCPA at early design stages, in a pattern of causes and effects as illustrated by Fig. 17. Based on these three obstacles, that leads to increase the lack of LCPA at early design stages, the authors suggest different propositions to be investigated in future developments. First, it is necessary to increase the real estate developer’s willingness to include LCPA into their design brief. As the construction sector is a highly constraining and cost-driven industry, there will be no interest in carbon mitigation by decision makers until the carbon emissions themselves have no economic impact. There is no doubt that LCPA will be of high interest by all construction stakeholders once the economic impacts will be as high as the environmental damages. Another powerful leverage to increase the market demand might be the EU regulation, extending the current energy consumption requirements to life-cycle performance requirements. A first step towards this direction has been proposed with a framework for LCPA at the EU scale (Dodd, Cordella, Traverso, & Donatello, 2017). In line with the greenhouse gas international agreements, it would make LCPA de facto mandatory in the client’s requirements. Second, there is a need to develop new LCPA methods with high efficiency at early design stages. On the one hand, the digitisation of the construction sector thanks to the Building Information Modelling methods (BIM) will allow a decrease in the input collection length. It will allow real time-assessment for the detailed design phases when the material quantities will be available. Simplified LCA and parametric approaches will also make LCA usable at early design as suggested by Hollberg’s work (Hollberg, 2017). On the other hand, LCPA outputs must deliver higher benefits with insights fitting the design process in terms of uncertainty and level of details, as most of the design choices are not defined yet. Here, new approaches as the LCA-based data-driven methods (Jusselme et al.,

Declaration of interests The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. Acknowledgement The work presented in this paper has been funded by the State of Fribourg (message du Conseil d’Etat au Grand Conseil 2014-DEE-22).


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Appendix A The questions and their possible answers when proposed, are listed in the following table


Answers when multiple choices are suggested

What is your age? What is your gender? In which country do you work? How would you best describe your profession? How would you best describe your position? What is the size of your company? Is your company involved in research and development activities? During building design, do you consider life cycle performance?(e.g. energy consumption or greenhouse gas emissions for the whole building's life cycle) In what kind of projects do you consider life cycle performance objectives? (multiple choices are possible) Individual housing Collective housing Office Commercial - Retail Hospital - Medical School - Educational Industrial Public - Governmental Other (please specify) Why do you analyze the life cycle performance of your building design? (multiple choices are possible) Because of the client's requirements. Because it is part of our best practices, and it is what we do in my company. Other (please specify) Using what kind of tool or method do you assess the life cycle performance at the conceptual design stage? Design guidelines Rules of thumb (According to the RIBA, the conceptual design stage is the first design stage, also called schematic Regulation and norm recommendations design, esquisse… Multiple choices are possible) Formulas / spreadsheets Computer software Technical and architectural references External consultant Internal consultant Other (please specify) On average, what is the time you spend to assess the life cycle performance of one building with your tool or method? (This includes collecting data, their implementation in your tool, and results interpretation.) What would you consider as a reasonable amount of time? What kind of other criteria do you also assess? (multiple choices are possible) Energy consumption Thermal comfort Lighting comfort Acoustic comfort Other (please specify) Which of the following Life Cycle Assessment (LCA) software do you use? Athena BeCost BEES Boustead Model Eco-SAI EcoEffect Ecosoft EIO-LCA e-licco - Cycleco Elodie CSTB Envest EQUER eTool GaBi LEGEP-LCA One Click LCA OpenLCA SimaPro Tally Tortuga Umberto Other (please specify) For each of the following criteria, how satisfied are you with the LCA tools you generally use? Transparency of the data Robustness of the results Tutorials and documentation User friendliness Visualization of the results Interoperability with CAD tools Time spent to conduct a LCA Cost of the LCA software Global satisfaction Other (please specify)


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Which percentage of your building design projects is evaluated using a LCA software? Regarding your LCA software, which training method did you use to get trained? (multiple choices are possible)

Please, tell us why you never consider life cycle performance?(multiple choices are possible)

Transparency of the data Robustness of the results Tutorials and documentation User friendliness Visualization of the results Interoperability with CAD tools Time spent to conduct a LCA Cost of the LCA software Response Self training with video, tutorial or documentation Helped by colleagues Internal/external training courses Other (please specify) I am not in charge of this task, but another member of my team/ company deals with it. It would be too time-consuming. It would be too expensive. It would require skills that I don't master. I don't think it is an interesting or useful analysis to perform. My clients don't request this type of analysis. Other (please specify)

Do you think that you may have to consider the life cycle performance of your building design in the future? Do you see building environmental regulations as an opportunity or as a threat? Neither of the two, I consider it as: Which parameters do you take into account during conceptual design stages?(multiple choices are possible) Glazing surfaces Windows properties Orientation Building shape Photovoltaïc panel surface Thermal panel surface HVAC system Lighting system Insulation thickness Insulation material type Structure type External wall covering Internal wall covering Indoor finishes Other (please specify) Did you know that starting from 2020, every new building in the European Union will have to generate more energy than it consumes? (EU regulation about Net Zero Energy Building) How critical is the environmental performance of your building project compared to your other constraints? How long does the conceptual design phase of your building project take? (amount of weeks on average) Do you usually integrate Building Environmental Consultants in your project at conceptual design stages? How many design alternatives do you produce at conceptual design stages, on average? How would you qualify the valuable input of Building Environmental Consultants to the design decisions? How satisfied are you with the environmental consultant's ability to understand your constraints, in general? Do you usually work with architects at conceptual design stages? How many design alternatives do you typically analyze at conceptual design stages, on average? How would you qualify the Architects' ability to integrate your valuable input into the design? How satisfied are you with the architects' ability to understand your constraints? What do you expect from a life cycle assessment? (multiple choices are possible) To check the compliance of my project with the client's brief or with regulations. To assess the performance of my project. To evaluate which design parameters are the most impactful on the building performance. To know what would be the technical and architectural optimum in terms of sustainability. To explore which of my design alternatives fulfill the life cycle targets. To compare the performances of different building design alternatives. Other (please specify) At conceptual design stages, where your project usually has a poor resolution of details, what kind of de- A simplified and approximated performance assessment of your cision support would you prefer to be provided with? (multiple choices are possible) project. A gallery of possible design options, to explore which fulfill the project needs and allow to reach the life cycle target. I don't know. Other (please specify) In your opinion, who should be in charge of integrating life cycle objectives into the design process? Do you have any other comments about this survey? Would you like to receive the results of this survey? If yes, please leave your email address here: (all collected data will be treated anonymously) Would you like to receive the results of this survey? If yes, please leave your email address here: (all collected data will be treated anonymously)

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