A Comprehensive Review of Sustainable Life Cycle Assessment in Residential Buildings

The body of life cycle assessment (LCA) literature is vast and has grown over the last decade at a dauntingly rapid rate. Many LCAs have been published on the same or very similar technologies or products, in some cases leading to hundreds of publications. One result is the impression among decision makers that LCAs are inconclusive, owing to perceived and real variability in published estimates of life cycle impacts. Despite the extensive available literature and policy need formore conclusive assessments, only modest attempts have been made to synthesize previous research. A significant challenge to doing so are differences in characteristics of the considered technologies and inconsistencies in methodological choices (e.g., system boundaries, coproduct allocation, and impact assessment methods) among the studies that hamper easy comparisons and related decision support. An emerging trend is meta-analysis of a set of results from LCAs, which has the potential to clarify the impacts of a particular technology, process, product, or material and produce more robust and policy-relevant results. Meta-analysis in this context is defined here as an analysis of a set of published LCA results to estimate a single or multiple impacts for a single technology or a technology category, either in a statisticalmore » sense (e.g., following the practice in the biomedical sciences) or by quantitative adjustment of the underlying studies to make them more methodologically consistent. One example of the latter approach was published in Science by Farrell and colleagues (2006) clarifying the net energy and greenhouse gas (GHG) emissions of ethanol, in which adjustments included the addition of coproduct credit, the addition and subtraction of processes within the system boundary, and a reconciliation of differences in the definition of net energy metrics. Such adjustments therefore provide an even playing field on which all studies can be considered and at the same time specify the conditions of the playing field itself. Understanding the conditions under which a meta-analysis was conducted is important for proper interpretation of both the magnitude and variability in results. This special supplemental issue of the Journal of Industrial Ecology includes 12 high-quality metaanalyses and critical reviews of LCAs that advance understanding of the life cycle environmental impacts of different technologies, processes, products, and materials. Also published are three contributions on methodology and related discussions of the role of meta-analysis in LCA. The goal of this special supplemental issue is to contribute to the state of the science in LCA beyond the core practice of producing independent studies on specific products or technologies by highlighting the ability of meta-analysis of LCAs to advance understanding in areas of extensive existing literature. The inspiration for the issue came from a series of meta-analyses of life cycle GHG emissions from electricity generation technologies based on research from the LCA Harmonization Project of the National Renewable Energy Laboratory (NREL), a laboratory of the U.S. Department of Energy, which also provided financial support for this special supplemental issue. (See the editorial from this special supplemental issue [Lifset 2012], which introduces this supplemental issue and discusses the origins, funding, peer review, and other aspects.) The first article on reporting considerations for meta-analyses/critical reviews for LCA is from Heath and Mann (2012), who describe the methods used and experience gained in NREL's LCA Harmonization Project, which produced six of the studies in this special supplemental issue. Their harmonization approach adapts key features of systematic review to identify and screen published LCAs followed by a meta-analytical procedure to adjust published estimates to ones based on a consistent set of methods and assumptions to allow interstudy comparisons and conclusions to be made. In a second study on methods, Zumsteg and colleagues (2012) propose a checklist for a standardized technique to assist in conducting and reporting systematic reviews of LCAs, including meta-analysis, that is based on a framework used in evidence-based medicine. Widespread use of such a checklist would facilitate planning successful reviews, improve the ability to identify systematic reviews in literature searches, ease the ability to update content in future reviews, and allow more transparency of methods to ease peer review and more appropriately generalize findings. Finally, Zamagni and colleagues (2012) propose an approach, inspired by a meta-analysis, for categorizing main methodological topics, reconciling diverging methodological developments, and identifying future research directions in LCA. Their procedure involves the carrying out of a literature review on articles selected according to predefined criteria.« less

Life cycle assessment of the building industry: An overview of two decades of research (1995–2018)

Global warming is the greatest environmental challenge that humanity is phasing. Water availability and biodiversity are also important issues of concern. Efforts towards achieving a sustainable path are required in all major sectors. The construction and infrastructure sector is an important contributor to global resource depletion and environmental impact. Life cycle assessment (LCA) is a frequently used tool to assess the potential environmental impact of a product or service throughout its life cycle. The life cycle of a product involves the extraction of raw materials, processing, production, use, and end-of-life. The environmental performance is quantified according to several impact categories such as: global warming, abiotic depletion, acidification, eutrophication, ozone layer depletion, photochemical oxidation, among others. LCA has been applied with success in the construction and infrastructure sector, in particular for buildings of all types. Literature in LCA of buildings use a variety of methodological approaches. The objective of this literature review is to identify and compare the different methodological approaches used in LCA of residential buildings, with a particular focus on functional unit, system boundaries, environmental impact categories, and data quality. The review indicates that there are different approaches used depending on the objective of each particular study.

A review of life cycle assessment of buildings using a systematic approach

Context The European Commission (EC) recognised Life Cycle Assessment (LCA) as "the best framework for assessing the potential environmental impacts of products". It also identified "the need to improve data availability and quality worldwide by internationally cooperating on LCA data and methods". The life cycle approach is also part of the 2011 Communication on "A resource-efficient Europe – Flagship initiative under the Europe 2020 Strategy". To support these life cycle based EU policies, the EC has started the "European Platform on Life Cycle Assessment (EPCLA)"[1]services (e.g. consulting or research services), tools (e.g. LCA tools, ecodesign tools), databases (e.g. LCI databases) and the corresponding developers and providers. in 2005. This Platform is implemented and coordinated by the EC Directorate-General Joint Research Centre (JRC), Institute for Environment and Sustainability, in close collaboration with DG Environment. The Platform works on the basis of coherent and quality-assured life cycle data, methods, and studies. The LCA Resource Directory is one of the deliverables of the Platform. This application has been running since 2006 and it contains lists of Novelty The LCA Resource Directory has recently been further developed so that it can contain and organize LCA case studies and metadata on these studies. The new LCA Resource Directory will be launched during the Fall 2011. Methods The new functionalities of the LCA Resource Directory allow users (LCA expert and non-expert) to browse a database of LCA studies. Thanks to the searching tool, a user can sort the information available as metadata and identify relevant LCA studies according to his/her interests. Many of the fields of the template used to characterize LCA studies are based on the ISO 1404x series. Some fields of the template are mandatory (e.g. functional unit and system boundary) in order to assure that the information showed in the application fulfills most of the requirements of the ISO 14044 for reports to be disclosed to the public. Other fields of the template include: "Intended application(s)", "LCIA impact categories" and "Compliance". The LCA study has to be uploaded on the Directory. Moreover, a final verification step is performed by the web application administrator to ensure quality and consistency. The application is open worldwide (http://lca.jrc.ec.europa.eu/lcainfohub/directory.vm). Any research group, company, university, etc. is now able, after registration, to upload studies and give metadata on them using a template. DG JRC will be in charge of the maintenance of the application and will populate the Directory with the first set of studies during the Fall 2011. An open call to relevant research groups and institutions will be send in order to populate the Directory with registered users and studies. Conclusions With these new capabilities of the Resource Directory, the EPLCA makes progress in its aim of promoting life cycle thinking when making available to all kind of LCA practitioners a good quality database of LCA studies, together with a searching tool. [1] http://lct.jrc.ec.europa.eu/

The building sector is one of the most relevant sectors in terms of environmental impact. Different functional units (FUs) can be used in life cycle assessment (LCA) studies for a variety of purposes. This paper aimed to present different FUs used in the LCA of buildings and evaluate the influence of FU choice and setting in comparative studies. As an example, we compared the “cradle to grave” environmental performance of four typical Brazilian residential buildings with different construction typologies, i.e., multi-dwelling and single dwelling, each with high and basic standards. We chose three types of FU for comparison: a dwelling with defined lifetime and occupancy parameters, an area of 1 m2 of dwelling over a year period, and the accommodation of an occupant person of the dwelling over a day. The FU choice was found to bias the results considerably. As expected, the largest global warming indicator (GWi) values per dwelling unit and occupant were identified for the high standard dwellings. However, when measured per square meter, lower standard dwellings presented the largest GWi values. This was caused by the greater concentration of people per square meter in smaller area dwellings, resulting in larger water and energy consumption per square meter. The sensitivity analysis of FU variables such as lifetime and occupancy showed the GWi contribution of the infrastructure more relevant compared with the operation in high and basic standard dwellings. The definition of lifetime and occupancy parameters is key to avoid bias and to reduce uncertainty of the results when performing a comparison of dwelling environmental performances. This paper highlights the need for adequate choice and setting of FU to support intended decision-making in LCA studies of the building sector. The use of at least two FUs presented a broader picture of building performance, helping to guide effective environmental optimization efforts from different approaches and levels of analysis. Information regarding space, time, and service dimensions should be either included in the FU setting or provided in the building LCA study to allow adjustment of the results for subsequent comparison.

Life cycle assessment and life cycle cost implication of residential buildings—A review

Life Cycle Assessment (LCA) has emerged as a vital approach for evaluating the environmental impact of building materials, products, energy consumption, and emissions throughout a building's lifespan, providing a comprehensive measure of building sustainability. In recent years, Türkiye's building sector has witnessed a substantial increase in the adoption of LCA, aligning with the nation's sustainability endeavours. This paper conducts a comprehensive review of 33 studies published within the last decade, focusing on residential and commercial buildings as well as industrial facilities in Türkiye. This study, therefore, fills an important gap by encompassing all common aspects of buildings within its LCA framework. Notably, LCA studies exhibit variability based on factors such as building type, geographical location, impact categories, system boundaries, and the specific LCA methodology employed. Türkiye's building sector is embracing LCA as a sustainability tool, despite challenges like lack of data and method standardization. The growing adoption of LCA is poised to contribute to enhanced sustainability practices in Türkiye's building industry, shaping a more environmentally conscious future. This research underscores the importance of standardized methodologies to facilitate a more cohesive and comparable analysis across diverse LCA studies.

According to some recent studies, noise from road transport is estimated to cause human health effects of the same order of magnitude as the sum of all other emissions from the transport life cycle. Thus, ISO 14′040 implies that traffic noise effects should be considered in life cycle assessment (LCA) studies where transports might play an important role. So far, five methods for the inclusion of noise in LCA have been proposed. However, at present, none of them is implemented in any of the major life cycle inventory (LCI) databases and commonly used in LCA studies. The goal of the present paper is to define a requirement profile for a method to include traffic noise in LCA and to assess the compliance of the five existing methods with this profile. It concludes by identifying necessary cornerstones for a model for noise effects of generic road transports that meets all requirements. Requirements for a methodological framework for inclusion of traffic noise effects in LCA are derived from an analysis of how transports are included in 66 case studies published in International Journal of Life Cycle Assessment in 2006 and 2007, in the sustainability reports of ten Swiss companies, as well as on the basis of theoretical considerations. Then, the general compliance of the five existing methods for inclusion of noise in LCA with the postulated requirement profile is assessed. Six general requirements for a methodological framework for inclusion of traffic noise effects in LCA were identified. A method needs to be applicable for (1) both generic and specific transports, (2) different modes of transport, (3) different vehicles within one mode of transport, (4) transports in different geographic contexts, (5) different temporal contexts, and (6) last but not least, the method needs to be compatible with the ISO standards on LCA. One of the reviewed methods is not specific for transports at all and two are only applicable for specific transports. The other two allow generic and specific road transports to be assessed. The methods either deal with road traffic noise only or they compare noise from different sources, ignoring the fact that not only physical sound levels but also the source of sound determines the effect. Three methods only differentiate between vehicle classes (lorries and passenger cars) while one method differentiates between specific vehicles of the same class. Four of the methods consider the geographic context and three of them differentiate between day- and nighttime traffic. None of the existing methods for traffic noise integration in LCA complies with the proposed requirement profile. They either lack the genericness for a wide application or they lack the specificity needed for differentiations in LCA studies. There is no method available that allows for appropriate inter- or intramodal comparison of traffic noise effects. Thus, the benefit of the existing methods is limited. They can, in the better cases, only demonstrate the relative importance of road or rail traffic noise effects compared to the nonnoise-related effects of transportation. Currently, none of the major LCI databases includes traffic noise indicators. Thus, noise effects are usually not considered in LCA studies. We introduce a requirement profile for methods that allow the inclusion of noise in LCI. Due to the estimated significance of noise in transport LCA, this inclusion will change the overall results of many LCA studies. None of the existing methods fully complies with the requirement profile. Two of the methods can be modified and extended for inclusion in generic LCI databases. A third model allows for intermodal comparison. From an LCA perspective, all methods include weaknesses and need to be amended in order to make them widely usable. In part 2 of this paper, an in-depth analysis of the promising methods is provided, improvement potential is evaluated, and a new context-sensitive framework for the consistent LCI modeling of noise emissions from road transportation is presented. Appropriate methods for modeling rail and air traffic noise will have to be developed in the future in order to arrive at a methodological framework fully compliant with the requirement profile. Furthermore, future research is needed to identify appropriate methods for impact assessment.

A statistical analysis of life cycle assessment for buildings and buildings’ refurbishment research

Life cycle assessment (LCA) techniques have been developed since the late 1960s in order to analyze environmental impacts of various products or companies. Although LCA techniques of forest production have been already conducted since the early 1990s, consistent and comprehensive LCA studies are still lacking for the forestry sector. In order to support better comparability between LCA studies, we analyzed the problems and differences by conducting a descriptive and quantitative analysis of existing LCA studies of forest production with special focus on Global Warming Potential (GWP). We analyzed 22 different peer-reviewed studies, four original reports and two databases. Important issues were, among others, the goal of the studies, system boundaries, functional units, impact categories and involved processes. In addition, a quantitative analysis was purchased where the results of the GWP of the reviewed studies were analyzed. The studies showed large differences between methodical assumptions and their subsequent results. For the GWP, we found a range of 2.4–59.6 kg CO2-equiv.*m−3 over bark (ob; median = 11.8; n = 41) from site preparation to forest road and 6.3–67.1 kg CO2-equiv.*m−3 ob (median = 17.0; n = 36) from site preparation to plant gate or consumer. Results varied as a function of the included processes and decisive assumptions, e.g., regarding productivity rates or fuel consumption of machineries. Raw wood products are widely declared as “carbon neutral,” but the above-mentioned results show that absolute carbon neutrality is incorrect, although the GWP is low compared with the carbon storage of the raw wood product (range of C-emitted/C-stored in wood is 0.008–0.09 from forest to plant gate or consumer). Thereby, raw wood products can be described as “low emission raw materials” if long-term in situ carbon losses by changed forest management or negative direct or indirect land use change effects (LUC, iLUC) can be excluded. In order to realize improved comparisons between LCA studies in the forestry sector in the future, we propose some methodical approaches regarding the harmonization of system boundaries, functional units, considered processes, and allocation assumptions. These proposals could help to specify the description of the forest production outlined in existing Product Category Rules for Environmental Product Declarations (e.g., EN ISO 16485 2014 or EN ISO 15804 2012) following EN ISO 14025 (2011) and for carbon footprinting standards like the Publicly Available Specification (PAS) 2050 (2011) or the European Environmental Footprinting Initiative.

Developments in life cycle assessment applied to evaluate the environmental performance of construction and demolition wastes

The relevance of exergy to the life cycle assessment (LCA) of buildings has been studied regarding its potential to solve certain challenges in LCA, such as the characterization and valuation, accuracy of resource use, and interpretation and comparison of results. However, this potential has not been properly investigated using case studies. This study develops an exergy-based LCA method and applies it to three case-study buildings to explore its benefits. The results provide evidence that the theoretical benefits of exergy-based LCA as against a conventional LCA can be achieved. These include characterization and valuation benefits, accuracy, and enabling the comparison of environmental impacts. With the results of the exergy-based LCA method in standard metrics, there is now a mechanism for the competitive benchmarking of building sustainability assessments. It is concluded that the exergy-based life cycle assessment method has the potential to solve the characterization and valuation problems in the conventional life-cycle assessment of buildings, with local and global significance.

To minimize the environmental impacts of construction and simultaneously move closer to sustainable development in the society, the life cycle assessment of buildings is essential. This article provides an environmental life cycle assessment (LCA) of a typical commercial office building in Thailand. Almost all commercial office buildings in Thailand follow a similar structural, envelope pattern as well as usage patterns. Likewise, almost every office building in Thailand operates on electricity, which is obtained from the national grid which limits variability. Therefore, the results of the single case study building are representative of commercial office buildings in Thailand. Target audiences are architects, building construction managers and environmental policy makers who are interested in the environmental impact of buildings. In this work, a combination of input–output and process analysis was used in assessing the potential environmental impact associated with the system under study according to the ISO14040 methodology. The study covered the whole life cycle including material production, construction, occupation, maintenance, demolition, and disposal. The inventory data was simulated in an LCA model and the environmental impacts for each stage computed. Three environmental impact categories considered relevant to the Thailand context were evaluated, namely, global warming potential, acidification potential, and photo-oxidant formation potential. A 50-year service time was assumed for the building. The results obtained showed that steel and concrete are the most significant materials both in terms of quantities used, and also for their associated environmental impacts at the manufacturing stage. They accounted for 24% and 47% of the global warming potential, respectively. In addition, of the total photo-oxidant formation potential, they accounted for approximately 41% and 30%; and, of the total acidification potential, 37% and 42%, respectively. Analysis also revealed that the life cycle environmental impacts of commercial buildings are dominated by the operation stage, which accounted for approximately 52% of the total global warming potential, about 66% of the total acidification potential, and about 71% of the total photo-oxidant formation potential, respectively. The results indicate that the principal contributor to the impact categories during the operation phase were emissions related to fossil fuel combustion, particularly for electricity production. The life cycle environmental impacts of commercial buildings are dominated by the operation stage, especially electricity consumption. Significant reductions in the environmental impacts of buildings at this stage can be achieved through reducing their operating energy. The results obtained show that increasing the indoor set-point temperature of the building by 2°C, as well as the practice of load shedding, reduces the environmental burdens of buildings at the operation stage. On a national scale, the implementation of these simple no-cost energy conservation measures have the potential to achieve estimated reductions of 10.2% global warming potential, 5.3% acidification potential, and 0.21% photo-oxidant formation potential per year, respectively, in emissions from the power generation sector. Overall, the measures could reduce approximately 4% per year from the projected global warming potential of 211.51 Tg for the economy of Thailand. Operation phase has the highest energy and environmental impacts, followed by the manufacturing phase. At the operation phase, significant reductions in the energy consumption and environmental impacts can be achieved through the implementation of simple no-cost energy conservation as well as energy efficiency strategies. No-cost energy conservation policies, which minimize energy consumption in commercial buildings, should be encouraged in combination with already existing energy efficiency measures of the government. In the long run, the environmental impacts of buildings will need to be addressed. Incorporation of environmental life cycle assessment into the current building code is proposed. It is difficult to conduct a full and rigorous life cycle assessment of an office building. A building consists of many materials and components. This study made an effort to access reliable data on all the life cycle stages considered. Nevertheless, there were a number of assumptions made in the study due to the unavailability of adequate data. In order for life cycle modeling to fulfill its potential, there is a need for detailed data on specific building systems and components in Thailand. This will enable designers to construct and customize LCAs during the design phase to enable the evaluation of performance and material tradeoffs across life cycles without the excessive burden of compiling an inventory. Further studies with more detailed, reliable, and Thailand-specific inventories for building materials are recommended.

LCA studies require a high volume of data and their quality has a direct influence on the quality of the Life Cycle Inventory (LCI) and Life Cycle Assessment (LCA) study overall. The use of LCA databases enables users to (i) reduce time, efforts, and resources for data collection and (ii) reflect supply chains they have no direct control over. On the other side, it creates the need to align own modeling of the foreground LCA study with the modeling in the database. In recent years, countries worldwide have been more and more motivated in supporting LCA studies by providing national databases that reflect their economy, energy mix, and disposal technologies. This article aims to give insights on the main needs, requirements, and challenges for the creation of an LCA database, with a special focus on national, reference databases. First, the article defines the main characteristics of LCA datasets and discusses data collection approaches. Secondly, LCA databases are defined, and the creation of LCA databases from developed datasets is addressed, including the case of national LCA databases. Finally, the existence of tools that could ease the LCA dataset and database creation process is investigated, namely the LCA Collaboration Server and the LCA Data-Machine. It is important that countries willing to create a national database are supported, for example with capacity-building workshops, by actors with a long tradition in the field, which is of mutual benefit: Countries with a long tradition in LCA will benefit from interactions with newcomers, for instance by discussing together unsolved methodological and interoperability issues; newcomers do not need to start from scratch but can benefit from gained experiences. Creating databases that provide specific data for various parts of the world supports LCA methodology and application in general, and it is not the least a chance for local LCA communities to bring in innovation into LCA, and benefit from existing experiences at the same time.