Implementation of Life Cycle Assessment (LCA) in the Procurement Process of Buildings: A Systematic Literature Review

Abstract

The construction industry adds a high share to global CO₂ emissions and, thus, to the global climate crisis. Future buildings need to be planned, constructed, operated, and deconstructed in a lifecycle-oriented manner so that the building stock represents a capital asset for future generations. The greatest leverages for reducing a building’s CO₂ emissions lie in the early project phase and subsequently in the tendering and awarding process, which makes early Life Cycle Assessment (LCA) indispensable. In this study, we set a sociological research framework consisting of (i) choosing a research topic, (ii) conducting a literature review, (iii) measuring variables and gathering data, (iv) analyzing data, and (v) drawing a conclusion. Since there are countless studies that apply LCA in the construction sector for environmental assessment, emission reduction, or decision support, we posed the question of whether LCA was also applied in the public building tendering and awarding process. Furthermore, we focused on identifying obstacles to LCA implementation in this early project phase. Therefore, we applied the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and conducted a Systematic Literature Review (SLR). The results show that numerous articles focused on sustainable tendering or green public procurement in the construction industry; however, the LCA method is scarcely used in the procurement processes (19 articles in the final sample). Based on our findings, the main obstacles to LCA implementation in the procurement process are highlighted in the study. In the future, the mandatory integration of LCA into the procurement process will be crucial to reduce the CO₂ emissions generated by the construction industry and thus contribute to the EU climate target plan to ensure carbon neutrality by 2050.

1. Introduction

In recent years the threats of climate change and remaining carbon budgets have been recognized by progressive efforts such as the Brundtland Report [1], the Rio Declaration [2], the Kyoto Protocol [3], and the 2030 Agenda for Sustainable Development [4]. In addition to these policy documents, the instruments of procurement have evolved in parallel [5]. With public procurement, in particular, the aim is for public actors to be role models and increasingly integrate environmental and social criteria into the procurement processes [6]. Various developments show that environmental and social requirements are increasingly important alongside economic efficiency [7,8,9].

In 2004 the guidelines of the public procurement environmental and social necessities were included as secondary considerations [10]. The EU directives 2004/17/EC and 2004/18/EC stipulate that contracts may be awarded to bidders based on price if the bidders meet the minimum requirements. In addition, a second alternative is permitted, namely awarding based on the economically most advantageous tender [11,12]. Adopting of these guidelines also formed the starting point for further developments such as green public procurement, sustainable procurement, and green procurement. In addition to regulatory developments, recent legislation has also favored green and social tendering and contracting in public procurement [10].

One of the aims of these two regulations is to reduce the carbon footprint and energy consumption of buildings. In order to meet the requirements of a carbon-neutral environment, the tendering and awarding processes of the construction industry must be further developed for this purpose [13].

Due to the enormous size of the construction sector, it contributes significantly to CO₂ emissions with its high material and energy flows. Consequently, it is a contributor to the ongoing climate crisis, highlighted by the significant share of global CO₂ emissions caused by buildings. Annual global building-related CO₂ emissions totaled 9.0 Gt CO₂ emissions in 2016 and have grown to approximately 10 Gt CO₂ emissions, according to the latest Global Status Report for Buildings and Construction. The share of embodied CO₂ emissions from construction accounted for more than one-third of this total, highlighting the increasingly important role of embodied CO₂ emissions [14]. Furthermore, the annual status reports published by United Nations Environment, the International Energy Agency, and the Global Alliance for Buildings and Construction report that 36 percent of global final energy consumption and 37 percent of energy-related CO₂ emissions can be accounted to buildings and their operations. In addition, the report shows that a further 10 percent of energy-related CO₂ emissions are generated by the sector referred to as the other construction industry [15]. Breaking down the share of embodied CO₂ emissions to the member states of the European Union (EU), CO₂ emissions from material extraction, construction product manufacturing, building construction, and refurbishment are estimated to be around 5–12 percent of the respective national CO₂ emissions [16]. With regard to the environmental impact of buildings, a literature review analyzed the environmental modeling of the building stock and presented corresponding EU policy initiatives [17]. In addition, frameworks already exist to harmonize the definition of the carbon budget of buildings from different perspectives and at different spatial and temporal scales [18]. Hence, future buildings need to be designed, constructed, operated, and deconstructed in a holistic and lifecycle-oriented manner, taking into account systemic interdependencies so that the building stock represents a capital asset for future generations and not a legacy [19,20]. In order to achieve these targets, methodical approaches and tools are already available to support sustainable construction, i.e., to support the implementation of more environmentally friendly construction through the reduction of CO₂ emissions [21,22]. In this context, the Life Cycle Assessment (LCA) method can be used to evaluate the environmental impacts of buildings and, thus, calculate the CO₂ emissions caused during their entire life cycle [23].

The method of LCA and its calculation rules are standardized for general use in the ISO 14040 and ISO 14044 standards [23,24]. In relation to these and other standards, e.g., ISO 9000 series or ISO 14001, which address topics such as quality management or environmental management, a difference can be made between organization-related standards and product-related standards [25]. An overview of these standards and their relations can be found in [26].

In the construction sector, the methodology was pushed forward by the CEN TC350, especially with the EN 15978, in which sustainability for the construction industry and the application of LCA for buildings are defined [27]. In recent years much research has focused on the methodological development of LCA, why the LCA is a widely applied method, especially in the construction industry [28]. In addition to methodological approaches, application at an early design stage of buildings is also under continuous development [22,29,30,31]. Numerous studies also showed the application of LCA for comparing variants of materials, construction elements, or buildings to evaluate the environmental impacts and to make sustainable decisions based on the results [32,33,34,35,36].

The rapidly growing field of LCA ”n th’ construction industry is reflected in numerous literature studies. Studies examined the application of LCA in the general context of the construction industry [36,37], and specifically the LCA application in the early project or design phase of buildings [38,39]. Further literature studies addressed LCA with a focus on embodied emissions and emphasized its importance in consideration of total emissions [17,40]. In this context, literature studies of LCA application for a wide variety of materials, such as timber, brick, concrete, or insulation materials, are also available [41,42,43,44]. Regarding construction materials, other studies went further into detail and investigated the application of LCA on those individual components of these materials using literature studies. These include, among others, the application of LCA to aggregates or cement mortar [45,46]. There are also already literature studies on the application of LCA for individual life cycle phases, such as the refurbishment phase or the end-of-life phase [47,48].

A recent study also analyzed the ”evel’pment of LCA in European policy. The results show that LCA is increasingly mentioned in policy, but the development of new and mandatory requirements related to LCA is still limited [45]. However, it appears that early assessment of the environmental performance of buildings will be mandatory in the future, but the voluntary wide practical application of LCA does not exist yet. Based on this observation, we were interested in determining the current status of LCA application in the building tendering and awarding processes. The first part of this study analyzed the question of whether LCA was applied in the procurement phase of buildings from the perspective of the literature. If LCA was not applied in the procurement phase of buildings, in the second part, we aimed to investigate why it was not applied and what the obstacles to implementation from a practical perspective were.

For this purpose, in this article, the main stages of the sociological research framework, (i) choosing a research topic, (ii) conducting a literature review, (iii) measuring variables and gathering data, (iv) analyzing data, and (v) drawing a conclusion, were applied in this article. The research topic addressed the application of LCA in the building procurement process. To gain better insights into the application of LCA in the tendering and awarding processes of public building projects, this article aimed to present the current state-of-the-art considerations of the LCA method in public procurement. For this purpose, the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were applied to conduct an SLR. The research included a pre-selection and evaluation of current and qualified literature studies to answer two specific research questions:

(i)

“Is LCA applied in the procurement processes of buildings?”

(ii)

“What is hindering the implementation of LCA in building procurement processes?”

While a few studies analyze the implementation of LCA in the construction procurement process based on real case studies and court cases [49,50,51], the novelty of our study lies in the comparison of this topic through a comprehensive literature review. Another uniqueness lies in identifying specific obstacles to LCA implementation that occur directly due to the implementation of LCA in the procurement process.

The following parts of this article are structured as follows. Section 2 discusses the materials and methods used in our research. Section 3 presents the results of the meta-data analysis, followed by the discussion of the findings in Section 4. Finally, the conclusions are drawn and the limitations and future research directions shown in Section 5.

2. Materials and Methods

2.1. Systematic Literature Review

The analysis and illustration of the current state-of-the-art consideration were conducted using a systematic literature review (SLR). The main steps of the SLR are (i) the definition of the research question(s), (ii) the definition of keywords and search strings, (iii) the definition of constraints (databases, search period, language, type of literature), (iv) article exclusion by title, (v) article exclusion by abstract, (vi) article exclusion by full paper and (vii) the analysis of meta-data. The process of the SLR is shown in Figure 1 based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) flowchart [52]. Detailed explanations on how to perform the SLR, as well as the included snowball approach, can be found in [53,54]. After completing both the SLR and the snowball approach a final sample was found consisting of 19 articles for in-depth analyses.

2.2. Preferred Reporting Items for Systematic Reviews and Meta-Analyses

The PRISMA 2020 Statement is the latest updated version on the guideline for conducting and reporting systematic reviews. The guidance consists of 27 items presented in a checklist and focueses on the introduction, the methods, the results, and the discussion section of a SLR [52,55]. The SLR performed in this article was consistent with the PRISMA 2020 Statement.

2.3. Snowball Approach

Snowballing is an approach within SLRs and can be divided into forward snowballing and backward snowballing. Both approaches work with cited references. While forward snowballing identifies new papers that reference papers already included in the final sample, backward snowballing examines the references of articles in the final sample and, thus, adds more relevant articles to the final sample [53].

2.4. Final Sample Identification Process

Based on the two defined research questions, the keywords procurement, tender, bid, award, life cycle assessment, LCA, environmental product declaration, EPD, product environmental footprint, PEF, and carbon footprint were defined for conducting the SLR.

It must be mentioned that the focus of the article was to analyze the current application of LCA in the procurement process of buildings and identify obstacles to implementation. However, keywords such as environmental product declaration, product environmental footprint, and carbon footprint were also used since LCA can also be closely associated with these terms and was a prerequisite for the generation of EPDs or the calculation of carbon footprints. Moreover, it aimed to enlarge the data pool from the beginning to avoid excluding any articles.

These keywords were combined in the search string (procurement OR tender OR bid OR award AND “life cycle assessment” OR LCA OR “environmental product declaration” OR EPD OR “product environmental footprint” OR PEF OR “carbon footprint”) using the Boolean operations “OR” and “AND”. The search for relevant articles was performed in two databases, ScienceDirect and Scopus. In the search, certain constraints were applied to limit the search results to relevant target articles. The first constraint was made based on the search period. The SLR included literature from the years 2000 to 2020. The second constraint was the language of the included literature, which was set to English only. The third constraint was the type of literature, which was set to review articles and research articles. The last constraint concerned the search area of the search string in the two databases. The search string was only applied to title, abstract, or author-specified keywords.

After applying the search string and the defined constraints in both databases, 569 articles were found. After excluding duplicates, the search comprised 358 articles. After that, the identified articles were further reduced based on the relevance of the title. This process was performed as a double-check, i.e., two persons each performed this step to increase the quality of the exclusion process. After this process step, 241 articles remained, which were further reduced in the next step based on the relevance of the abstract. This process step also took place as a double-check. This exclusion process resulted in 31 articles for the final full paper analysis. Detailed screening of the 31 articles revealed that 13 articles were relevant in answering the research questions and were thus included in the final sample.

After conducting the SLR, the snowball approach was used as an additional iterative step. In the case of the snowball approach, the reference list was screened from the 31 articles analyzed, and further relevant articles were identified based on references. This first step of the snowball approach resulted in an additional 62 articles, which were reduced to 59 articles after removing duplicates. As with the SLR, the exclusion of articles by the relevance of the title (48 articles left) and abstract (33 articles left) was based on the double-check principle. All the exclusion steps were performed by humans, and no automation tools were used. The detailed full paper analysis of the 33 articles resulted in 6 relevant articles that were included in the final sample. In the end, the final sample for the meta-data analysis consisted of 19 articles.

3. Obstacles to the Implementation of LCA in the Procurement Process of Buildings

Derived from the identified literature based on the defined keywords and constraints during the SLR, a final sample of 19 articles resulted. From this, it can be deduced that the method of LCA is scarcely applied in the procurement process of buildings. Obstacles to LCA implementation in the procurement process were various and could be categorized according to different aspects. To answer the question of obstacles to LCA implementation, five obstacle classifications were defined: (i) methodological obstacles, (ii) organizational obstacles, (iii) legal obstacles, (iv) political obstacles, and (v) economic obstacles.

Methodological obstacles refer to the LCA method itself and can also be described as general obstacles that do not occur directly in the implementation of the construction procurement processes. In addition to these general obstacles, the other obstacle classifications represent specific obstacles that occur in implementing LCA in the building procurement process. Organizational obstacles are individual obstacles that can occur to varying degrees in individual companies, and these obstacles are particularly dependent on the size of the organizations. Legal and political obstacles are mainly based on a lack of legal requirements and initiative to support alternative building procurement processes. However, it should be noted that methodological, legal, and political obstacles, in particular, are interdependent. If there are too many methodological obstacles, it is difficult for policymakers and legislators to take the next steps toward mandatory LCA implementation in the tendering and awarding process. Economic obstacles are those that prevent LCA implementation primarily because of the additional cost involved.

Figure 2 shows the occurrence of the addressed categories in the final sample.

3.1. Methodological Obstacles

An identified obstacle on the methodological level was the lack of comparability for the different LCA tools and results in the LCA process, e.g., allocation or impact categories, for tender requirements [56,57,58,59]. In this context, the different ranking results of variants for different indicators were also highlighted as obstacles [60]. Furthermore, in addition to the lack of practical and operational tools, the high complexity of the LCA process made the implementation of LCA in the tendering and awarding procedure difficult [59,61,62,63,64,65,66,67]. Moreover, a lack of information, e.g., missing guidelines, handbooks, or toolkits, was mentioned as a problem for LCA implementation [59,61,65]. Process-based obstacles and problems in the procurement procedure context included different challenges to be tackled in the award criteria, meaning that environmental preferences were formulated in a way that is too unspecific or they were difficult to measure in the first place [67,68]. On top of this, the assessment criteria and the award criteria did not always correspond to the importance of the environmental issue [68]. Additionally, the distinct use of tender processes or award criteria could also be an issue, as well as the tendency to use environmental criteria more often with higher project budgets or on a national level [61,68]. Lastly, the lack of methods that enabled comparisons, quality control, and monitoring was mentioned [67]. In terms of data quality, the availability of data and data uncertainty were also identified as methodological obstacles [60,67].

Table 1. Methodological obstacles to the LCA implementation in the procurement process of buildings.

Methodological Obstacles	Reference
Review of PEF guide and EPDs Comparison between the PEF guide and the EPD requirements → PEF and EPDs are not comparable in terms of results → PEF and EPDs in their current form cannot be alternatively used as tools supporting GPP tender requirement	[56]
Review of to-date EPD programs for pavement materials Discussion about stakeholders’ perspectives on the current EPD program with material manufacturers, public government agencies, and LCA consultants Use of EPDs in GPP to ensure the environmental improvement of materials and pavements → EPDs aggregate a LCI into a handful of mid-point indicators, which can undermine the details of the supply chain	[57]
Discussion with stakeholders (owner/client, designer, and contractor) about EPD implementation Application of EPDs during the design and construction stage using an office building as case study → Lack of result comparability of different LCA tools	[58]
LCA/TOPSIS method is applied to public procurement of urban furniture Simplified LCA methodology combined with TOPSIS method for assessing award criteria → Lack of guidelines/handbooks for LCA implementation → No monetization of LCA results	[59]
LCA is applied to road bridges to push LCA implementation in procurement Comprehensive LCA framework for road bridge procurement → Different ranking results for different indicators → Uncertainties in data	[60]
Content analysis of the documents obtained from calls for tenders Comparison of environmental criteria in tenders → Complex LCA process → Missing guidelines or toolkits → Distinct use of tender processes or criteria → Use of environmental criteria with higher project budgets	[61]
Semi-structured interviews about current practices and obstacles to environmental requirements in construction Survey about the existence of municipal policies dealing with environmental issues → Lack of data quality about material inventories → Environmental performance requirements are too complex → Lack of guidance and standardization at national level	[62]
LCA for design selection and decision-making during material procurement of asphalt mixtures Analytical approach to identify equivalence intervals that are applicable during material procurement decision-making → High complexity of the LCA process → Lack of uncertainty analysis within LCA	[63]
Structured interviews on the assessment of environmental aspects and the review of environmental requirements Survey about including environmental requirements in procurement documents → Complexity of LCA analysis → Lack of evaluation of operating energy → Lack of LCCA integration → Lack of assessment models	[64]
Assessment of the determinants and drawbacks of green procurement adoption → Lack of guidelines and tools to support GPP	[65]
LCA is applied to wood windows to support procurement criteria definition → Lack of practical and operational tools	[66]
Literature review of obstacles and drivers for sustainable buildings Interviews about obstacles and drivers for sustainable buildings Case studies on improving the sustainable building process and the impacts and benefits of sustainable buildings → No methods that enable comparisons, quality control, and monitoring → No methods to verify the compliance of subcontract’s work with the sustainability requirements → Lack of available information → Design documents do not show adequate performance and capacity requirements for the products	[67]
Interview series to achieve insights into application of environmental preferences in construction projects Survey about the application of environmental preferences in the procurement of construction contracts → Environmental criteria are weighted less heavily → Environmental criteria have therefore no influence on the results of the evaluation	[68]

provides an overview of the identified methodological obstacles. The applied methodological approaches of the research articles (italic), as well as the obstacles, are mentioned.

Within the methodological obstacles, the lack of standardization at a national level was mentioned as an implementation obstacle. However, as far as the LCA method is concerned, the international standards ISO 14040 and ISO 14044 define the calculation principles of LCA [23,24]. In addition, there is even a standard for the application of LCA to calculate the environmental performance of buildings [27]. The application of these standards and, therefore, the application of LCA in the construction industry is already far-reaching and, therefore, cannot be an obstacle to implementation. In addition, the lack of guidelines and handbooks was mentioned a few times as a barrier to implementation. In terms of LCA implementation in general and specifically for the calculation of embodied emissions, guidelines for designers, policymakers, and manufacturers have already been developed [69,70,71,72]. Regarding the implementation of LCA within the building’s procurement process, these guidelines and handbooks are lacking, as the assessment of the environmental performance of buildings in the course of tendering and awarding is uncharted territory and is still scarcely applied in practice. In this context, new approaches are currently being developed in the research project “Paris Buildings” [73]. For the calculation of the economic performance of buildings, i.e., life cycle costing (LCC), there are already guidelines in Austria for the implementation of LCC in the building procurement process [74,75]. Based on these guidelines, a guidance document for the implementation of LCA in the building procurement process could also be oriented.

Regarding the LCA process, its complexity was highlighted as a problem for application in the procurement process. Closely related to this, the problems of varnishing of the data and also data quality due to underlying uncertainties are also emphasized. To make the complexity manageable, the know-how on all sides of the project participants must be increased. Nevertheless, sustainability assessment experts are recommended (especially in the initial application phase) in order to support the mandatory implementation of LCA in the tendering and awarding of buildings. By consolidating these experts, the valid examination of the submitted offers is guaranteed by complete, transparent, and consistent LCA. Although numerous LCA databases such as Ecoinvent, ELCD database 3.1, GaBi Database, and Ökobaudat are available, new/specific data sets will always be needed due to the uniqueness of buildings [76]. Implemented sustainability experts can also close the practical gap concerning “data-lack,” since new project-specific data sets can be modeled by themselves. This is crucial in terms of time expenditure during a mostly strong limited planning phase.

In the uncertainty context, this was equal for all bidders, i.e., all submitted bids, if external and independent experts were involved. Regarding the lack of data in relation to the operating energy that was mentioned, it could be referred to the national obligatory energy standards [77]. How the effects of different energetic standards influenced the results of the LCA was investigated in [78]. The mentioned lack of assessment models can be solved only partially in the future. Due to the fact that each building is unique, the development of a generally applicable assessment model/tool is not reasonable. In this context, however, there were already several approaches to automatically link LCA databases with Building Information Models (BIM) [79,80]. LCA software, such as SimaPro, Gabi, Umberto, and openLCA [81,82], has been available for decades but is often associated with high acquisition costs.

Regarding the LCA results, the problem here was that different results were obtained with respect to the best-case scenarios depending on the considered environmental indicators, i.e., for the environmental indicator of Global Warming Potential, a different scenario was better than for the environmental indicator of Eutrophication Potential. If all environmental indicators are taken into account, this problem can only be solved with a defined weighting of the different indicators and their normalization to one value [83]. However, the first important step was the consideration of environmental indicators that address the most vulnerable areas of the planetary boundaries [84,85].

In the context of considering environmental indicators in the tendering and awarding process, the obstacle to the lack of monetization opportunities for environmental indicators was mentioned. However, recent literature has already provided conversion values for many environmental indicators [86,87,88,89]. Sensible values of these conversion factors to achieve meaningful environmental optimization (based on so-called “environmental break-even” points) are currently being analyzed within the research project “Paris Buildings” [73].

3.2. Organizational Obstacles

In terms of organizational obstacles, one challenge was missing environmental knowledge within existing organizations and the lack or limited knowledge connected with LCA and other green public procurement (GPP) tools [61,62,90,91]. In this context, the insufficient knowledge to develop clear targets and mitigating strategies and the problem that contractors were not able to explain sustainability criteria to subcontractors were highlighted as obstacles [62,65,67]. In addition, there was a lack of common goals because not all stakeholders shared the same conviction for addressing environmental issues [92]. A further challenge occurred if there were no clear responsibilities assigned to the LCA [62]. The problem with LCA implementation was often that green alternatives like supply chains or services were unavailable [65,90,92,93]. Another challenge was the fear of high- and time-consuming bureaucracy and project delays [68]. In addition, a lack of access to appropriate data was a significant challenge to the application of LCA [62,64,66]. Finally, the lack of time to compare alternatives, as well as the lack of training for employees, were described as organizational obstacles [58,65,67,92].

Table 2. Organizational obstacles to LCA implementation in the procurement process of buildings.

Organizational Obstacles	Reference
Discussion with stakeholders (owner/client, designer, and contractor) about EPD implementation Application of EPDs during the design and construction stage using an office building as case study → Lack of time to apply an LCA	[58]
Content analysis of the documents obtained from calls for tenders Comparison of environmental criteria in tenders → Missing knowledge and skill regarding LCA and other GPP tools	[61]
Semi-structured interviews about current practices and obstacles to environmental requirements in construction Survey about the existence of municipal policies dealing with environmental issues → Lack of skills related to LCA tools and methods	[62]
Assessment of environmental impacts of two different hot mix asphalt (HMA) materials to provide evaluation parameter in public bids → Lack of comprehensive approach for application to different civil works → Lack of green alternatives	[93]
Structured interviews on the assessment of environmental aspects and the review of environmental requirements Survey about including environmental requirements in procurement documents → Lack of knowledge of environmental strategies → Lack of input data → Lack of expertise in assessing environmental impacts	[64]
Assessment of the determinants and drawbacks of green procurement adoption → Lack of training for employees → Difficulties in the preparation of tenders and purchases → Lack of information about environmental impacts	[65]
LCA is applied to wood windows to support procurement criteria definition → Lack of appropriate data	[66]
Literature review of obstacles and drivers for sustainable buildings Interviews about obstacles and drivers for sustainable buildings Case studies on improving the sustainable building process and the impacts and benefits of sustainable buildings → Insufficient knowledge to develop clear targets and mitigating strategies → Contractors are not able to explain the sustainability criteria for subcontractors → Client lacks an actor who supports him in setting targets for sustainability requirements → No resources to supervise the realization of sustainability requirements → Not enough time to compare alternatives	[67]
Interview series to achieve insights into application of environmental preferences in construction projects Survey about the application of environmental preferences in the procurement of construction contracts → Fear of high- and time-consuming bureaucracy → Insufficient knowledge → Fear of project delays	[68]
Assessing the environmental impact of road works to promote green procurement using multi-criteria analysis → Lack of knowledge connected with LCA → Technical and organizational difficulties during the management of green tenders	[90]
LCA is applied for two products to support procurement decision → Additional time effort for LCA application → Lack of know-how in the field of LCA	[91]
Semi-structured interviews to develop a framework for a carbon emission encompassed tender Framework for a carbon emission encompassed tender → Lack of a common goal because all stakeholders must be convinced → Missing know-how in implementing low carbon measures for small firms → Project constraints in terms of design and specifications	[92]
Development of the Thai National LCI Database → Lack of stakeholder awareness → Lack of LCA expertise	[94]

provides an overview of the identified organizational obstacles.

Among the organizational obstacles, the additional time required to conduct LCAs in the procurement process was cited as an implementation barrier. This obstacle cannot be completely eliminated, as additional tasks usually require additional time. However, the complex LCA process and, thus, the time required can be significantly reduced through the generation of know-how and accumulated project experience, and, as mentioned above, the implementation of sustainability experts can close this gap. Nevertheless, it must be mentioned that the main hurdle for most organizations was still the real and substantial implementation of sustainability concepts [95]. In addition to the lack of time to conduct LCA, the lack of time relating to designing and comparing more environmentally friendly alternatives was also mentioned as an obstacle to implementation. Overcoming these obstacles requires a transformation of the design process [96] and more innovative remuneration models. For example, in Austria, there was already a fee structure in the form of scheduled services and fees for architects and engineers (HOAI), which defined special services in addition to standard services.

Early LCA implementation in the tendering and awarding process of buildings also failed due to the lack of know-how within the organizations involved. This problem was based on the fact that it is currently not common practice to implement LCA in the procurement process of buildings and that organizations do not offer their employees either any training or further education opportunities in this subject area. In this context, however, it must be mentioned that this transformation of the design process towards sustainable procurement of buildings is a further step similar to the application of BIM. BIM is already state-of-the-art in many planning offices and is constantly being further developed. In BIM, there are, in addition to the 3D building models, also possibilities to consider 4D (cost), 5D (time), and 6D (sustainability aspects) models [97,98,99].

In addition to the lack of time and know-how, missing access to data for the organization was also mentioned as an implementation obstacle. In this regard, however, it must be emphasized that there are freely accessible databases such as Ökobaudat. On the other hand, several databases are not freely accessible and must be purchased through high license fees. In this context, harmonizing all LCA databases would be an important step for a future, environmentally friendlier construction industry.

An obstacle to implementation on the part of awarding authorities was the lack of awareness and understanding to explain clear targets related to the implementation of sustainability aspects. Recently, there has been an increasing awareness of sustainable building procurement. In Austria, for example, the city of Graz already uses a developed form sheet for climate change and sustainability on a voluntary basis in the course of architectural competitions [100]. Other approaches, such as the use of a systemic design process or a maturity assessment, can further raise awareness and contribute to the reduction of CO₂ emissions in the construction industry [21,22].

3.3. Legal Obstacles

The problems in the area of legal obstacles lay in missing compulsory environmental requirements by law, such as the use of LCA in tender processes [61,90]. The lack of regulations for public tenders was mentioned in this context [101]. Furthermore, attention was drawn to the lack of clarity in the law regarding environmental requirements [62]. These two mentioned obstacles were emphasized by the lack of consistent format in terms of legal requirements [91]. Moreover, the institutionalization of green procurement is slow due to the absence of extensive and well-defined rules for incorporating environmental criteria into procurement procedures and awarding contracts for goods and services [65].

Table 3. Legal obstacles to LCA implementation in the procurement process of buildings.

Legal Obstacles	Reference
Content analysis of the documents obtained from calls for tenders Comparison of environmental criteria in tenders → Missing compulsory environmental requirements for LCA implementation	[61]
Semi-structured interviews on the subjects of current practices and obstacles to environmental requirements in construction Survey on the subject of the existence of municipal policies dealing with environmental issues → Law is unclear regarding environmental requirements	[62]
Assessment of the determinants and drawbacks of green procurement adoption → Absence of extensive and well-defined rules for incorporating environmental criteria into procurement procedures and the awarding of contracts for goods and services	[65]
Assessing the environmental impact of road works to promote green procurement using multi-criteria analysis → Missing compulsory environmental requirements	[90]
LCA is applied for two products to support procurement decision → Lack of consistent format in terms of legal requirements	[91]
Review of EPDs Comparison of EPDs and NAPs → No regulations for public tenders	[101]

provides an overview of the identified legal obstacles.

In the context of the legal obstacles, the unclear legislative regulations regarding environmental requirements were highlighted as an implementation barrier to early LCA application. With reference to these findings, it is worth mentioning that the procurement directives, i.e., EU directives 2004/17/EC and 2004/18/EC, have evolved towards greener procurement in recent years. However, the contents defined leave a relatively high scope of action in terms of (practical) implementation [11,12]. Especially the application of LCA is still on a voluntary basis. Furthermore, it was criticized that there are no regulations for public tenders. However, in this context, there are approaches for green public procurement of office buildings to integrate LCA into the procurement process [102].

3.4. Political Obstacles

In the context of the obstacles under policy aspects, municipal authorities did not use the right to set sustainability requirements as award criteria. Further obstacles mentioned in the literature were the lack of a comprehensive strategy for public procurement and the lack of governance of regulation, regardless of its nature, which could be either performance-based or prescriptive [67]. Moreover, it was mentioned that more than just the indicator of global warming potential (GWP) should be considered as environmental criteria [93]. Lastly, missing supporting initiatives for the implementation of LCA in the procurement process were highlighted as a problem [94].

Table 4. Political obstacles to LCA implementation in the procurement process of buildings.

Political Obstacles	Reference
Literature review of obstacles and drivers for sustainable buildings Interviews about obstacles and drivers for sustainable buildings Case studies on improving the sustainable building process and the impacts and benefits of sustainable buildings → Municipal authorities do not use the right to set sustainability requirements as award criteria	[67]
Assessment of environmental impacts of two different hot mix asphalt (HMA) materials to provide evaluation parameter in public bids → Lack of a comprehensive strategy for public procurement → More than GWP should be considered as environmental criteria	[93]
Development of the Thai National LCI Database → No supporting initiatives	[94]

provides an overview of the identified political obstacles.

Among the political obstacles to implementation, the lack of comprehensive strategies for public procurement was mentioned. Clear strategies for implementing LCA in the tendering and awarding process of buildings do not exist to a sufficient extent. However, sustainability strategies, in general, are increasingly being pushed forward. In this regard, the 17 Sustainable Development Goals (SDGs) within the framework of the 2030 Agenda must be mentioned [4]. Within these goals, SDG 11 “Sustainable Cities and Communities” should be highlighted, which, among other issues, promotes more environmentally friendly construction. As part of the UniNEtZ research project, options for action were developed for the Austrian federal government to achieve the SDGs, which, among other matters, also propose and explain the implementation of LCA in the procurement process of buildings [103]. Another policy instrument that has already been implemented in the context of CO₂ emissions reduction is the implementation of CO₂ taxes.

Another obstacle to implementation mentioned was the lack of supporting initiatives. An organization, e.g., a publicly financed consulting office, could be established here, at least for public buildings, which would provide support in adapting the tender documents, as well as sustainability experts who would carry out the transparent evaluation of the bids. A public consulting office can also overcome the implementation obstacle of municipalities not using the right to set sustainability requirements as award criteria.

3.5. Economic Obstacles

The main factors hindering LCA or GPP implementation on the economic level were resource constraints, i.e., intensive resources for data management, lack of time, and the enormous time requirement for applying an LCA tool [57]. Next to the lack of time, the increased costs were mentioned in the literature. In this context, the establishment of standardized procedures was described as long, which led to a high initial cost [62,64,91]. Staff training for this process also brought financial burdens [62]. In detail, the problems lay in the shortage of resources for supporting GPP, the fear of even further increased costs, and the fact that developers may not be willing to bear these additional costs [58,65,68,92]. An obstacle was also identified as the lack of funding support for LCA implementation, e.g., for LCI development [94].

Table 5. Economic obstacles to LCA implementation in the procurement process of buildings.

Economic Obstacles	Reference
Review of up to-date EPD programs for pavement materials Discussion about stakeholders’ perspectives on the current EPD program with material manufacturers, public government agencies, and LCA consultants Use of EPDs in GPP to ensure the environmental improvement of materials and pavements → Collecting EPDs to establish benchmarks is resource intensive and requires advanced data management	[57]
Discussion with stakeholders (owner/client, designer, and contractor) about EPD implementation Application of EPDs during the design and construction stage using an office building as case study → Additional cost for LCA application → Consideration of environmental products can lead to additional cost regarding transport	[58]
Semi-structured interviews about current practices and obstacles to environmental requirements in construction Survey about the existence of municipal policies dealing with environmental issues → Establishing standardized procedures is time consuming and costly → Process of training staff is time consuming and costly	[62]
Structured interviews on the assessment of environmental aspects and the review of environmental requirements Survey about including environmental requirements in procurement documents → High initial cost	[64]
Assessment of the determinants and drawbacks of green procurement adoption → Lack of money to support GPP	[65]
Interview series to achieve insights into application of environmental preferences in construction projects Survey about the application of environmental preferences in the procurement of construction contracts → Fear of increased cost	[68]
LCA is applied for two products to support procurement decision → Additional cost for LCA application	[91]
Semi-structured interviews to develop a framework for a carbon emission encompassed tender Framework for a carbon emission encompassed tender → Developers may not be willing to bear additional cost	[92]
Development of the Thai National LCI Database → No funding supports for LCI development	[94]

provides an overview of the identified economic obstacles.

From an economic persepective, the obstacles to LCA implementation in the tendering and awarding phase were very clear. The additional costs were highlighted as a barrier to implementation. These additional costs were seen in the broader sense as environmental damage costs. The construction of new buildings increases CO₂ emissions and, thus, has a negative impact on our environment. In general terms, there are two different theoretical approaches to monetizing these external environmental damages, the damage cost approach and the abatement cost approach. In the abatement cost approach, the focus is not on the cost of the damage caused but on the cost of abatement. The cost incurred by these measures, i.e., the additional cost for LCA implementation, are referred to as abatement costs [104]. In general, there are already standards in the EU for the calculation of environmental damage costs [105,106]. However, in addition to the calculation principles of the LCA, a monetization value such as the CO₂ price must also be specified in the tender documents.

Another obstacle to implementation, which specifies the additional cost mentioned above, was the additional cost required to establish standardized procedures, which companies were unwilling to pay. Training costs for the staff to build up LCA expertise also fell under this additional cost. These barriers were further compounded by the fact that there are no funding supports for the implementation of early LCA. The establishment of a so-called “(public) climate fund,” which also addresses the pre- and post-procurement phases, could reduce these additional costs during the initial implementation of more environmentally friendly building projects.

4. Discussion

The increase in the number of new buildings due to rising urbanization increases the share of CO₂ emissions caused by the construction industry. Current tendering and awarding practices for buildings are mainly focused on minimizing cost and almost completely disregard environmental criteria when awarding contracts. However, standards and tools, like LCA, for assessing the environmental performance of buildings are already available. There are only a few real case examples of implementing LCA in building procurement processes [50]. The determination of obstacles to applying LCA at this early project stage is still ambiguous. Identifying these obstacles will help project stakeholders avoid these hurdles in advance and thereby reduce CO₂ emissions emitted by the construction industries through more environmentally friendly tendering and awarding procedures.

For the state-of-the-art identification of LCA implementation in the procurement process of buildings, and thus for the determination of obstacles, an SLR was conducted. The SLR results show that the implementation of LCA in the procurement process of the construction industry is scarcey addressed in the scientific literature. This is the case despite the fact that the concept of procurement is constantly developing in the direction of environmental procurement in European directives and national action plans with terms such as green procurement, sustainable procurement, and environmental procurement. The identified obstacles to overcome were summarized within the following five categories (i) methodological obstacles, (ii) organizational obstacles, (iii) legal obstacles, (iv) political obstacles, and (v) economic obstacles.

The classified obstacles were divided into general and specific obstacles. While methodological obstacles occurred due to the LCA method itself and are not directly related to the tendering and awarding process of buildings, specific obstacles, i.e., organizational, legal, political, and economic obstacles, occurred directly due to LCA implementation in the building procurement process.

At the methodological level, an approach to implementing LCA in procurement was to establish a well-accepted methodological framework and transparency regarding the use of methods and data. Additionally, the need to develop LCA tools for the whole building was expressed in the literature. For better decisions, and as well in combination with different methods, LCAs should be used as a decision-making tool to judge various alternatives and their environmental implications. For example, the method of comparative LCAs or EPDs was used to push alternatives with lower environmental impacts [28]. The application of environmental criteria could be integrated into the tendering of building services and construction contracts. Another approach was to implement criteria in the preliminary architectural competition [100].

At the organizational level, managers and leaders are crucial when it comes to incorporating environmental preferences into policy documents. Another starting point for improving the situation for LCA in tender documents is the importance of communication and coordination between stakeholders. Improving skills and knowledge transfer, as well as strengthening capacity regarding LCA and awareness of the topic in general, played an important role. Especially education and training regarding the topic of LCA and environmental issues of relevant stakeholders were important. Another important prerequisite for conducting LCA is high-quality LCA data that is scientifically sound, consistent, reliable, and comparable.

At the legal level, appropriate guidelines, tools, and manuals are needed to provide the necessary knowledge for LCA and its mandatory implementation. In addition, standardized methods for the assessment of construction products would be beneficial and should be regulated at the legal level. In this context, the lack of mandatory anchoring of LCA in the tendering and awarding process, as well as award decisions based on financial aspects, i.e., the principle of the lowest bidder, were highlighted.

In the political context, both the lack of regulatory control, which could be either performance-based or prescriptive, and the lack of a comprehensive environmental strategy for public projects were described as obstacles. Moreover, the leadership of government and professional institutions must be introduced to green procurement if greener procurement is desired.

At the economic level, an approach to financing the additional effort involved in conducting an LCA needs to be developed. Instruments such as environmental management control in the pre-procurement and post-procurement phases or climate funds could help here. Furthermore, within the economic category, additional costs due to increased time and effort were mentioned.

In summary, most of the obstacles were found in the methodological and organizational categories. The reasons for not applying LCA were the lack of comparability between different LCA tools, the high complexity of the LCA process, and the lack of information, e.g., user-friendly guidelines, handbooks, or toolkits. These problems were amplified by the missing environmental knowledge within existing organizations and the lack of limited knowledge connected with LCAs. In addition, in most organizations, there are fewer green alternatives and often no access to the necessary data to perform an LCA. It can be argued that most of the obstacles in the three categories of methodological aspects, organizational aspects, and economic aspects can be removed more quickly if appropriate measures are taken at the political and legal levels. However, it must be mentioned that the classified obstacles occur occurred at different levels and are, therefore, not directly comparable. Furthermore, these levels of obstacles were also interrelated and therefore influenced each other. In particular, methodological obstacles influence political and legal obstacles and vice versa. If there are too many methodological obstacles, it is difficult for policymakers and legislators to take the next steps toward mandatory LCA implementation in the building procurement processes.

Not to be neglected in this context is the assessment of the cost efficiency of buildings. In the EU Directives, the concept of life cycle costing (LCC) was mentioned in Article 68. It stated that an “LCC may also include the costs of externalities (such as greenhouse gas emissions).” This requires the use of LCA in the procurement process to calculate GHG emissions. Life cycle costing remains optional, but according to Article 68(3), life cycle costing became mandatory when there was a common EU methodology [107].

The limitations of the study lay in the selection and number of databases. Over the course of the SLR, the databases ScienceDirect and Scopus were used. Further limitations concern the constraints that were made within the SLR. The search period was limited to the years 2000 to 2020. Regarding the defined keywords, the performed SLR only included articles that fell under the defined keywords and the search strings produced by combination with the Boolean operators. Other synonyms for the defined keywords were not taken into account. However, it should be mentioned that the selected keywords are the frequently used technical terms in the procurement process of buildings and the application of LCA. Only review and research articles in the English were used for metadata analysis. No gray literature was thus considered. Country-specific documents and documents in languages other than English were therefore not included. Finally, there was another limitation regarding the exclusion and assessment of publications. No assessment of publication bias was made. However, the study selection was performed by two reviewers, thus using the double-check principle to avoid subjective assessment. With regard to the final sample, it must be mentioned that due to the existing research gap, the number of articles within the final sample was not representative. The classified obstacles, therefore, do not claim to be complete.

Future research approaches for the implementation of LCA in the procurement process of buildings must be well planned in order not to limit know-how in terms of the development of greener alternatives of bidders by imposing the mandatory use of LCA. Currently, a GHG emission bonus/malus system is being developed, which foresees a mandatory application of LCA in the course of tendering and awarding. In this bonus/malus system, CO₂-eq. is added to or subtracted from the bid price by means of a CO₂ price as a so-called shadow price. As a results of this more innovative approaches, e.g., green alternatives and solutions, are now being promoted by bidders as a strategy for staying competitive in the future [108,109]. Furthermore, the cooperation of all involved stakeholders, i.e., LCA scientists, CEOs of companies, legislators, and policymakers, is crucial for overcoming the obstacles together.

5. Conclusions

This article summarizes the results of a systematic literature review (SLR) on the application of life cycle assessment (LCA) in the procurement processes of public buildings. The aim was to determine the current state of research on this topic and where the obstacles to implementation occur.

The results show that numerous articles discussed sustainable tendering or green public procurement in the construction industry, however, the LCA method was scarcely used in the procurement process. When examining the obstacles, different solutions can be taken into consideration on distinct levels. The identified obstacles to overcome were summarized within the following five categories (i) methodological obstacles, (ii) organizational obstacles, (iii) legal obstacles, (iv) political obstacles, and (v) economic obstacles.

Concepts for integrating LCA into the procurement process need to be developed, researched, tested, and, most importantly, implemented rapidly in order to reduce further CO₂ emissions caused by the construction industry. Therefore, a mandatory integration of LCA in the procurement process is needed. One effective method for implementing CO₂ emission constraints monetarily is as an award criterion by applying the method of Whole Life Costing, i.e., to calculate externalities.

The obstacles identified show where adjustments need to be made in order to establish the implementation of LCA in the tendering and awarding process for buildings in the future. The results thus contribute to the EU’s Climate Target Plan to ensure carbon neutrality by 2050. In the future, so-called carbon budgets for certain construction measures will further support and accelerate the implementation of sustainable construction. In this context, a greenhouse gas emissions bonus/malus system is currently being developed as part of the “Paris Buildings” research project, which will consider selected externalities in the awarding process and promote more environmentally friendly submitted projects. Further efforts for more sustainable procurement will also be essential requirements for the architectural competition. Requesting sustainability aspects at this early stage can be a further lever for implementing sustainable construction.