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Building walls are responsible for the highest share of environmental impact among other building elements and the whole building envelope is linked to nearly half of the energy embodied in the building. One of the sustainable materials that may be applied in building envelopes to reduce their impact is paper, e.g. corrugated cardboard or paperboard. Although environmental qualities are considered the key advantage of paper, the environmental properties of previously proposed designs were rarely assessed nor compared to conventional building envelopes. Therefore, the aim of this research is to analyse the performance and environmental impact of selected paper-based envelopes, compare them with conventional alternatives based on steel and timber, and indicate key factors influencing their environmental performance. Moreover, the article proposes two original paper-based envelopes with favourable environmental characteristics. The environmental analysis was conducted via Life Cycle Assessment, using the midpoint CML method and the endpoint ReCiPe method with a single indicator. LCA was based on the Ecoinvent 3.8 database and supplemented with sensitivity analysis. LCA results were compared with performance assessment. It has been shown, that replacement of conventional envelopes with paper-based ones, especially in buildings with a limited lifespan, may reduce their environmental impact and the amount of waste generated. In conclusion, a series of recommendations for sustainable paper-based envelope designs are formulated. [Display omitted] • Paper-based building envelopes may reduce buildings' environmental impact. • A combination of LCA and performance analyses may be used for envelopes' assessment. • Envelopes with embedded structural elements are preferable to sandwich structures. • Durable yet sustainable claddings are crucial for paper-based envelopes' performance. [ABSTRACT FROM AUTHOR]

Housing aims to provide society with comfortable, healthy living spaces and its built form ultimately shapes the built environment. Consequently, its design, operation, and interactions with infrastructure systems are a powerful determinant of environmental, economic, and social impacts. This paper highlights the importance of assessing housing built forms by answering ten critical research questions. Throughout this paper, we refer to housing built form as the physical properties (e.g., residential density, floor area ratio) of residential buildings and their interactions with adjoining properties (e.g., setback, shading). In Q1 and Q2, we summarize the planning policies that led to current built forms associated with housing and their sustainability impacts, with specific focus on North America and some countries in Australasia. Q3 describes the adverse sustainability impacts of detached single-family houses, while Q4 examines future economic, demographic, and climatic changes that will warrant rethinking housing built form. Q5 summarizes the methods to assess the environmental, economic, and social impacts of housing built form. In Q6 and Q7, we discuss various system boundaries and functional units that are considered for housing life cycle assessment. Q8 and Q9 describe the temporal uncertainty and contextual circumstances underlying housing projects that need to be considered in life cycle assessments. Lastly, Q10 provides a summary of future policy directions to promote housing with lower environmental impact. This paper supports decision-making around meeting housing targets without compromising the environment. • Ten relevant questions on housing built form considering planning policies and impact assessment tools are posed. • Housing built forms are determinant of environmental, economic, and social impacts. • Past, present, and future housing built forms are reviewed. • Life cycle assessment is a useful tool for analyzing the environmental impact housing built form. • Planning policies to support and increase competitiveness of low impact housing built form are provided. [ABSTRACT FROM AUTHOR]

There is general agreement on the importance of green roofs as ways of reducing GHG emissions, reducing overall costs and improving sustainability in urban areas. This systematic literature review highlights life cycle sustainability assessment as an essential criterion to evaluate green roofs. A bibliometric analysis was used to quantitatively review relevant literature. The Scopus database was chosen as a bibliographic database of academic publications. Thes period of search started from 2003 and final search was conducted on February 15, 2023. Based on further in-depth reading, 88 publication records which met the selection criteria, including 74 papers and 14 conference papers. Researchers from the United States contributed almost 31 % of the documents. We evaluated leading studies in this field and discussed assessment method, system boundaries and research gaps through a critical literature review and a systematic search review. Finally, we propose a framework and identify a gap and future research. The environmental aspect of green roofs have received more attention than economic issues. We found that most economic evaluations of green roofs are limited to their construction stage. As yet there is no comprehensive social study on green roofs. We considered a unified study of the economic, environmental impact and social evaluation of green roofs to be warranted. Additionally, various measurement methods should be used to assess the economic profitability of green roofs over the long term. In summary, this study provides a deeper understanding of the environmental, social, and economic performance of green roofs and identifies research gaps as well as future research directions. [ABSTRACT FROM AUTHOR]

Efficient thermal insulating materials can significantly reduce energy consumption for both heating and cooling of buildings. When selecting an insulation material, however, it is important to consider other important aspects, such as acoustic performance, environmental impacts, effects on human health and costs of production. That is the reason why key research developments are recently achieved in the field of sustainable, highly efficient materials. Within this context, this paper deals with the thermal and acoustic performance and the environmental impact analysis of two kinds of corrugated multi-layer cardboard panels, usually applied in the packaging industry. Thermal analyses were conducted in order to measure the thermal conductivity by means of both an experimental campaign and numerical methods. The acoustic absorption coefficient and the transmission loss were experimentally determined by means of an impedance tube. Finally a Life Cycle Assessment of the considered panels was implemented and compared to the performance of other commonly used insulation materials. The main results of the study show that the cardboard-made panels usually applied for low-cost packaging present promising performance in terms of both acoustic and thermal insulation potential, i.e. of the same order of magnitude than high-performance commercialized products. The environmental impact evaluation also reveals an interesting behavior of the corrugated cardboard panels, which can by any means be considered as a promising recycled insulation material. [ABSTRACT FROM AUTHOR]

Remountable building elements can be transformed according to our changing requirements, ensuring a long use of materials and buildings. To stimulate the implementation of remountable building elements, their environmental impact can be quantified through life cycle assessment (LCA). For a fair comparison between remountable and non-remountable building elements, transformations must be accounted for in LCAs. Yet, currently this is often not done. The purpose of this paper is to develop easy-to-use formulas to calculate the number of transformations and material replacements for remountable and non-remountable building elements. Different types of transformations are considered and it is analyzed how material replacements interact with transformations of the building element. The research is executed on two types of building elements: space dividing walls in offices and façade systems. The robustness of the developed formulas, further referred to as the simple formulas, is examined by comparing their results to those calculated by detailed formulas used in previous research, which determine the moment of occurrence of transformations and replacements. For each building element, the LCA results calculated by the simple and detailed approach are compared for numerous scenarios. In certain cases, the simple formulas over- or underestimate the number of replacements, but the majority of scenarios show limited differences. Furthermore, both approaches yield the same conclusions in a comparative LCA of the remountable and non-remountable space dividing wall. The simple formulas demonstrate how the calculation methods of LCA tools used in practice could be adapted to include the evaluation of remountable building elements. • LCAs of remountable building elements must model multiple cycles (transformations). • Formulas on the number of transformations and material replacements are defined. • Complex transformations where the type or quantity of materials change are studied. • It is analyzed how material replacements interact with transformations of the element. • The formulas form a good approximation of more detailed formulas of previous research. [ABSTRACT FROM AUTHOR]

The competition for limited urban spaces due to the growing demand for both living space and green areas causes conflicts in urban development. This paper aims to provide urban planners with a systematic multi-criteria decision making process and a supporting tool-chain. The process uses multi-objective optimization (MOO) to quantify trade-offs, allowing planners to gain a broad perspective on optimal solutions. The generic process builds an urban simulation model, applies MOO, explores the results in terms of multi-criteria trade-offs, and guides the decision making of urban planners. To enable this process, we present a tool-chain for applying a Gaussian Process Regression based MOO algorithm to a computationally expensive urban simulation model. The tool-chain allows to identify Pareto-optimal solutions and their properties with reasonable computational effort. A case study model is set up in the Grasshopper environment and couples simulation components for outdoor thermal comfort and Life Cycle Assessment. It allows to identify multi-objective trade-offs for a high-dimensional space of urban configuration degrees of freedom such as outdoor vegetation, photovoltaics, and building characteristics. We compare the workflow results to other MOO algorithms and show how it can support decision making in urban planning at early design phases. In our case study, the tool chain was able to investigate the multi dimensional space of urban configurations. It systematically identified Pareto-optimal solutions therein and reduced the number of model evaluations significantly. The case study results showcase the trade-off between lifecycle-based global warming potential (GWP) and outdoor thermal comfort. We identified the number of trees and the coverage of the east and west façades with photovoltaics as the most important parameters. The proposed process proves to be a powerful multi-criteria decision support tool for urban planners. It allows to identify and quantify the Pareto Front of competing urban target trade-offs at early design phases. Additionally, it visualizes them according to the boundary conditions of urban development. The input configurations of the obtained Pareto-solutions serve as a base of urban planning recommendations. In our case study, trees and photovoltaics prove to be good levers in the area of GWP optimal solutions. However, urban planners need to carefully coordinate inputs when aiming for a specific trade-off balance. The tool-chain and the simulation model offer further potential for investigating neighborhood typologies. Thereby, applicants can derive scalable guidance to support the sustainable transformation of the urban environment. [Display omitted] • Structured process to explore the space of Pareto-optimal solutions in urban systems • Surrogate models allow to derive a continuous Pareto Front for decision making • First use of the Paref MOO algorithms in a computationally expensive urban simulation • Trade-off between lifecycle-based GWP and outdoor thermal comfort is quantified • Urban trees and building photovoltaics are important to steer this trade-off [ABSTRACT FROM AUTHOR]

The 2050 decarbonization goals coupled with the growing housing shortage in Europe intensify the pressure on new-build dwellings to enhance their energy performance. Beyond a zero operational energy, the focus has shifted towards reducing embodied carbon (EC). Against this backdrop, this study investigates the simultaneous impact of downsizing and the use of timber in new-build dwellings, EC reduction strategies seldom explored concurrently. Through partial life cycle assessments, three scenarios are modelled: the Small, Medium, and Large House, with two construction variations for each, comparing a modular timber design to a conventional concrete alternative. Designs are based on dwellings built in Almere, the Netherlands. Data is extracted from the Swiss Ecoinvent database using the TOTEM tool and the static −1/+1 approach for biogenic carbon accounting is adopted. Results show a total EC ranging from 42,608 to 70,384 kgCO 2 eq for the timber designs versus 54,681 to 91,270 kgCO 2 eq for their concrete counterparts. Findings suggest that the relationship between house size and EC is sublinear whereby a house twice the size entails less than twice the EC emissions. Only the simultaneous implementation of downsizing and the use of timber achieved 53% carbon savings. The discussion explores implications of outcomes across academic, industry and policy perspectives, challenges in implementing smaller timber dwellings, and study limitations and future research. Beyond its empirical contribution, this paper offers a practical contribution with its hierarchical data analysis approach covering building, element and component. This approach can be implemented by researchers and practitioners alike to inform their design process. • Downsizing and timber are assessed in tandem as embodied carbon reduction strategies. • The embodied carbon of actual European housing scenarios is investigated. • A proposed hierarchical approach decomposes the house into elements and components. • The hierarchical analysis links architectural design choices to embodied carbon. • A small timber house consumes half the embodied carbon of a large concrete house. [ABSTRACT FROM AUTHOR]

Concepts for setting carrying capacity-based benchmarking of life-cycle environmental impacts is an ongoing field of research with an emerging industrial uptake in the built environment. This paper is a critical review of this development compiled in the form of 10 questions that discusses issues and challenges related to definitions, methodology, terminology, and uncertainties. The intention is not to discourage the development but to highlight the need for ensuring consensus and alignment on the aforementioned issues both within the research community and when implementing concepts in practice. Concluding that AESA (Absolute Environmental Sustainability Assessment) aims to address the environmental performance of a service, benchmarked against a functional pollution space, using environmental carrying capacities, rather than comparing it to current 'best practice'. It is crucial to recognize that these carrying capacities are limits, not targets, and whilst allocation of the carrying capacity to services depends on subjective and political decision-making, uncertainties, including subjectivity and emerging scientific data, should be included and communicated clearly in credible AESAs. Collaboration between academia and industry is crucial to align definitions and terminology and avoid misalignments. While AESA lacks a scalable approach for systemic assessments, it serves as a valuable steppingstone for transition, highlighting that achieving a built environment within the currently known functional pollution spaces, requires policy changes and a cultural shift. • Status of research and pitfalls when implementing AESA in the building industry. • Ten questions and answers are posed on AESAs in the Built Environment. • AESA should be based on carrying capacities, defining a functional pollution space. • It is crucial to recognize that carrying capacities are limits, not targets. • Uncertainties should be included and communicated clearly in credible AESAs. [ABSTRACT FROM AUTHOR]

In the last decade, many studies focused on finding optimal design solutions considering trade-offs between different aspects of building design. Accordingly, multi-objective optimization (MOO) approaches have been increasingly applied in the building industry. However, certain aspects must be deepened to ensure a more effective decision-making process in the early planning phase. On the one hand, uncertainties should be considered before making decisions to ensure the robustness of the optimal solutions; on the other hand, decisions are made at different times in building planning, and the sequential order of making decisions should be modeled. This paper presents a holistic two-stage multi-objective stochastic optimization (MOSO)-II framework to minimize the environmental impact of global warming potential (GWP) and cost throughout the entire life cycle of a building (phases of A1-A3, B4, B6 and C3-C4), considering passive and active design strategies in two consecutive stages, under uncertainty. Herein, individual/use and political/market uncertainties are considered. As a proof of concept, the proposed framework is applied in a case study for a generic zone in a multi-family terraced residential building type with solid brick construction. The advantages of the proposed framework are validated by comparing it with alternative single-stage MOSO frameworks. Results show that the proposed two-stage MOSO-II framework can deliver a smaller range of solutions with a better performance in terms of lower GWP and cost. It indicates that the proposed framework can effectively assist planners in decision-making by reducing the effort in choosing the proper solution. Secondly, the results also emphasize the importance of passive design strategies in sustainable building planning. In addition, the energy mix structure and cost of energy sources should be carefully adjusted in the future to promote a more ecologically sustainable building design. • A two-stage multi-objective stochastic optimization framework for building design. • Passive and active design strategies as two decision stages in building planning. • Targeting at minimum global warming potential and cost in the optimization problem. • Integration of uncertainties in the decision-making process for early design phases. [ABSTRACT FROM AUTHOR]

When calculating buildings' environmental impact through life cycle assessment (LCA), simplifications in the life cycle inventory phase of technical installations are common. Often authors argue that these simplifications are essential to minimize time and effort. However, it is unclear to what extent these simplifications are justified. The challenge lies in establishing simplified models that do not compromise the robustness of results, which first requires detailed LCAs. Therefore, this paper aims to acquire knowledge about (1) the significance of individual components in heating and ventilation systems' design, (2) the relative contribution of technical installations to embodied and life cycle impacts at building level, and (3) the difference between a detailed and simplified approach to derive guidelines for simplified calculations. In this research, a Flemish single-family dwelling is adopted as reference building, including six heating and four ventilation scenarios. Firstly, the current state-of-the-art in research on the environmental impact of technical installations is outlined. Secondly, an extensive data inventory is performed, suggesting different approaches to address data limitations. Finally, the environmental impact is calculated over a 60-year study period, following a cradle-to-grave methodology. The results show that a simplified approach, considering only generation systems, underestimates embodied and life cycle impacts by 8–12 % and 4–6%, respectively. Technical installations contribute 12–33 % to the embodied impacts of the new build dwelling, whereas in the context of the overall life cycle impact, technical installations contribute 5–20 %. Moreover, the study highlights the environmental significance of individual heating and ventilation components beyond generation systems. • The importance of technical installations in whole-building LCA is studied. • Detailed LCA of heating and ventilation systems in a single-family dwelling. • Technical installations contribute up to 33 % and 20 % to embodied and life cycle impacts. • The study shows the HVAC components' significance beyond generation systems. • A simplified approach underestimates embodied and life cycle impacts up to 12 % and 6 %. [ABSTRACT FROM AUTHOR]

Life Cycle Assessment (LCA) is globally recognized as one of the most complete methods for environmental assessment of buildings. Literature assumes that its applications in the building sector are prejudiced regarding complexity and difficulty. However, simplification is necessary, since it can facilitate LCA application in buildings. Moreover, growing interest on reducing environmental impact in the building sector, as well as the relevance of single-family houses on CO 2 emissions have become key points on the wide spread of LCA. Therefore, this paper presents a research study about simplification in LCA recent studies applied to single-family houses. The review focuses on 20 cases that were analyzed according to ISO 14040, ISO 14044, EN 15978, and EN 15804 standards. The main objective was to identify the simplification strategies assumed in each paper, to clarify and to help to promote further developments on LCA. This paper examines system boundary definition, data sources, life cycle phases included, and environmental impact indicator calculated in case studies. Results show the variety of simplifications identified. They affect physical model definition, life cycle scenario definition and communication of results. In most cases, the functional unit was the complete building, the life cycle scenario definition included production, use and demolition phases, and the most considered environmental impact indicator was GWP. Finally, new challenges and recommendations were defined in order to establish common criteria to develop simplification strategies that allow results comparability in LCA of single-family houses. [ABSTRACT FROM AUTHOR]

Building information modeling (BIM) helps simplify data acquisition and reduce labor-intensive processes in the life cycle assessment (LCA) of buildings. However, there is a lack of systematic understanding of integrating BIM into LCA. This paper aims to develop a framework for systematically reviewing the body of knowledge on BIM-integrated LCA in the concept, methodology, and value dimensions. Following the framework, this paper analyzes case studies involving 82 buildings from selected publications between 2011 and 2021, using scientometric and detailed content analysis techniques. The results evidence that the majority of them were studies of residential, low-rise, and concrete buildings and used Autodesk Revit for establishing BIM models. Three types of methods for BIM-integrated LCA were identified: integrating data into a third-party application or tool (I), importing a bill of quantities report generated from the BIM model into a dedicated LCA tool (II), and using plug-ins with LCA data for BIM software (III). However, interoperability between BIM and LCA remains a serious challenge owing to different terminologies and data structures. Hence, two means have been suggested to improve this: adapting the BIM data to the LCA data structure and developing a simpler BIM tool. This paper provides a theoretical foundation for better understanding "what BIM-integrated LCA is", "how to integrate BIM with LCA to simplify and automate data input", and "what applications of BIM-integrated LCA are". It also serves as an information base for researchers and software developers to identify the contemporary research trends and knowledge gaps in this discipline. • BIM-integrated LCA is systematically explained in concept, methodology and value dimensions. • Three knowledge gaps of BIM-integrated LCA research are examined by analyzing 82 case buildings. • Three types of methods for BIM-integrated LCA are identified. • The interoperability between BIM and LCA is the most significant challenge. • Standardizing the data structures contained in the BIM model is vital for LCA. [ABSTRACT FROM AUTHOR]

Demountable building is put forward as a solution to reduce the environmental impact of the construction sector. However, uncertainty on the actual environmental benefits that can be achieved, hinders its implementation. Life cycle assessment (LCA) can be used to measure the potential of demountable building. Variable design and use parameters, such as the number of use cycles and material lifespan, should be incorporated in LCAs of demountable building elements to account for different possible use scenarios. Existing LCAs of demountable elements only vary one parameter at a time and/or consider simple reuse scenarios and building elements. The aim of this paper is to show how LCAs of demountable building elements can be organized by focusing on influential design and use parameters, while resolving the limitations from existing research. The influence of the parameters is determined through a two-step sensitivity analysis executed for two types of building elements: space dividing walls and façade systems. First, parameters with a low influence are omitted through a screening sensitivity analysis. Then, the Sobol' indices of the remaining parameters are calculated. The results show the influential parameters are the same for both types of building elements. Finally, an LCA with variable influential parameters for a demountable and non-demountable space dividing wall is conducted. According to a non-variable LCA, the non-demountable wall has the lowest environmental impact, but when considering variable parameters, the use scenarios for which the demountable wall has the lowest impact become clear, for example, when the wall is relocated every five years. • LCAs of demountable elements are performed by focusing on influential variables. • The LCA considers multiple cycles through transformations of the building element. • The same parameters are found influential for space dividing walls and façade systems. • The 'study period' and 'transformation frequency' are the most influential parameters. • For all parameter variations demountable walls are favored if relocated every 5 years. [ABSTRACT FROM AUTHOR]

Abstract: Glass curtain wall (CW) systems have been inevitable elements of commercial buildings for over a century. The systems mainly consist of mullion materials and glazing units that are selected and designed to achieve the desired structural, thermal and daylighting performances as well as to meet cost and aesthetic concerns. The health and environmental life cycle impacts of CW systems, however, are not usually considered in design. The main objective of this paper is to study how change of mullion materials would affect the health and environmental impacts associated with a typical CW system over its life cycle. The mullion materials studied for the purpose of this paper include extruded aluminum, carbon steel and glulam timber. Also, the health and environmental impact categories of interest include global warming, acidification, eutrophication and human toxicity. To achieve the objective, a process-based cradle-to-gate attributional Life Cycle Assessment (LCA) method was applied. Results indicate that CW system with glulam timber mullions causes the least and CW system with extruded aluminum mullions causes the most damage to the environment and human health over their life cycle. A CW system with carbon steel mullions falls in-between. [Copyright &y& Elsevier]

Abstract Buildings are responsible for a large share of greenhouse gas (GHG) emissions. The use of Life Cycle Assessment (LCA) during the design phase can help to improve the environmental performance of buildings. However, designers and clients find it difficult to set environmental performance targets and interpret the results obtained through LCA in order to improve the building design. Therefore, reference values or benchmarks are needed. Current available LCA-based benchmarks have mostly been developed for certification systems on whole building level and do not provide design guidance on material or element level. To close this gap, this paper introduces an alternative approach that supports the design process by providing guidance and encouraging to improve the environmental performance. The aim of this approach is to support exploiting the optimization potential particularly regarding the embodied GHG emissions related to the manufacturing of construction products and to the construction, maintenance and demolition of the building. The concept consists in combining top-down benchmarks per capita derived from the capacity of the global eco system with bottom-up reference values for building components that are defined based on a statistical best-in-class approach (top 5%) using the market share of different construction products. Benchmarks for GHG emissions for new residential buildings in Switzerland are discussed. The results of applying the dual benchmark approach to a case study show that it can facilitate the use of LCA-based tools for design support and promote the optimization of the building-related environmental performance. Highlights • Novel dual benchmark approach for greenhouse gas emissions during the life cycle of buildings to support the design process. • Determination of top-down targets based on the 2° goal and a global carbon budget per capita. • Determination of bottom-up targets for building elements based on a statistical approach using market share data of building materials in Switzerland. • Application of the method for analysis of the environmental optimization potential in the design process. [ABSTRACT FROM AUTHOR]

Abstract: A companion paper presented the life cycle inventory (LCI) calculation model for buildings as a whole, developed within a global methodology to optimise low energy buildings simultaneously for energy, environmental impact and costs without neglecting the boundary conditions for thermal comfort and indoor air quality. This paper presents the results of a contribution analysis of the life cycle inventory of four typical Belgian residential buildings. The analysis shows the relative small importance of the embodied energy of a building compared to the energy consumption during the usage phase. This conclusion is even more valid when comparing the embodied energy of energy saving measures with the energy savings they realise. In most studied cases, the extra embodied energy for energy saving measures is gained back by the savings in less than 2 years. Only extremely low energy buildings might have a total embodied energy higher than the energy use of the utilisation phase. However, the sum of both remains small and the energy savings realised with these dwellings are large, compared to the energy consumption of average dwellings. [Copyright &y& Elsevier]

In response to establishing net-zero carbon emissions buildings and the need to make transparent the methods used for calculating the embodied CO2e emissions of these projects, this paper presents a case study of one project. The paper first outlines the life cycle assessment method used, including system boundaries, data availability, scenarios, assumptions, and uncertainties. Whole building life cycle assessment results show normalized embodied CO2e emissions of 488 kg CO2e/m2. If system boundaries are aligned to current benchmarking studies, this value is 233 kg CO2e/m2. When considering system boundaries, the results show that upwards of 42% of the project's CO2e emissions are generated by technical systems beyond those accounted for in contemporary life cycle assessment studies. The paper also provides a method to calculate the building's carbon balance over its 100-year service life based on multiple future energy supply CO2-intensity scenarios. The results show that the building can achieve carbon balance under conservative scenarios when a zero-carbon emissions energy supply is not achieved by 2050. The results illustrate the importance of transparency when declaring zero-carbon balance in a project. The uncertainties of such a declaration are also discussed, along with the relationship of the building's operational and embodied carbon emissions. • A transparent whole building lifecycle assessment study is provided. • Renewable and MEP systems have a significant impact on lifecycle carbon emissions. • Zero-carbon balance can be achieved; results are sensitive to study scenarios and scope. • Building design, materials selection, and embodied carbon benchmarking are discussed. [ABSTRACT FROM AUTHOR]

Reducing greenhouse gas emissions in the built environment is key to mitigating climate change. This paper uses Life Cycle Assessment (LCA) to explore whether glue-laminated timber (glulam) has a significantly lower whole-life embodied carbon (Global Warming Potential; GWP) than functionally-equivalent structural steel. Alongside a baseline assessment that follows standard practice, a variety of further sensitivity analyses establish how differing assumptions affect results. Assessment found that the GWPs were highly dependent on: (1) the assumed end-of-life scenarios; (2) the approach used to consider biogenic CO 2, and; (3) whether the timing of emissions was considered. In general, glulam had the lowest GWP when incinerated (with energy recovery) at end-of-life. However, when recycling is modelled according to current standards, glulam GWPs were in amongst those of steel, giving no clear ranking of materials. Landfilled glulam had a lower GWP than steel if some biogenic carbon was assumed to be permanently stored. That may be appropriate given recent guidance from the Intergovernmental Panel on Climate Change, but is not allowed in the updated standards for LCA of construction products (e.g. EN 15804:2019). Six additional impact categories were also assessed to give a broader environmental comparison. The relative impact of the two materials depended on the impact category assessed, with glulam generally having a similar or lower impact than steel. Given the findings of this paper, further research on end-of-life treatment and LCA methodology is critical to ensure that strategies aiming to reduce GWP by material selection are effective in practice. • Functionally-equivalent LCA comparison of structural timber and steel. • Consideration of all possible end-of-life treatment options. • Exploration of how the timing of GHG absorptions and emissions affects results. • Clear summary of how methodology affects perceived climate performance. [ABSTRACT FROM AUTHOR]

This paper aims to introduce a framework that applies life cycle cost (LCC)-based optimization, life cycle assessment (LCA) and multi-criteria decision-making (MCDM) methods for the selection of optimum envelope materials and AC systems for housing projects. A total of 37 selection criteria and 28 material alternatives were first identified through a comprehensive literature review and interviews with local experts. "DesignBuilder", a computer simulation software, was used to conduct the LCC-based optimization and LCA for the identified alternatives. Furthermore, uncertainties and risk associated with the selected alternatives were computed using Monte Carlo simulation via the Crystal Ball software and Efficient Frontier analysis via the Excel Spreadsheets. The identified selection criteria were then prioritized and assigned with utility scores based on the analytical hierarchy process (AHP) and multi-attribute utility theory (MAUT) methods. Seven scenarios with different objectives were set for an existing case study. The implementation of the framework showed that when taken into account the application of multi-criteria methods, the highest saving combination of materials is selected by the framework. The validation process was carried out through conducting interviews with local experts based on the results obtained from real case project. The experts agreed that the proposed framework can be beneficial to the industry as it takes into consideration not only quantitative criteria, but also qualitative criteria that are important to owners and designers. • A framework is proposed for selecting envelope materials and AC systems for residential buildings in hot-humid climate. • Life cycle cost and environmental impact of materials and systems are analyzed. • Uncertainties and risk associated with cost elements and other parameters are analyzed. • Sensitivity analysis is conducted to identify factors affecting LCC calculations. • Quantitative and qualitative criteria that affect the selection are identified and considered. [ABSTRACT FROM AUTHOR]

Vernacular (indigenous) buildings have been proven to be adaptive to climatic conditions. However, their water footprint benefits have not been discussed in the literature. This research aims to provide an in-depth evaluation of the influence of vernacular structures (including adobe, brick, stone, and wood) compared to modern structures (steel and concrete) on the water footprint of a selection of 42 residential buildings. The paper proposes that when building construction follows vernacular patterns, the contribution of the building industry to water pollution and water resources can be substantially reduced. Grey and blue water footprints are computed throughout production chains by employing water footprint accounting and life cycle inventory techniques. The grey water footprints of vernacular buildings are 327 times smaller than the grey water footprints of modern buildings. For modern buildings, the grey water footprint is dominated by the grey water footprint of steel and cement production. The blue water footprint of vernacular buildings is mostly related to construction personnel. While traditional building practices represent an important part of cultural heritage and have the potential to provide insights into sustainable and resource-efficient building practices, there are concerns regarding their compliance with present-day construction codes and standards. Therefore, this study evaluates the water footprint of both vernacular and contemporary building practices, taking into account their potential for sustainable building practices. • Comparing vernacular and modern structures based on the water footprint concept. • Analyzing various factories and a wide range of real residential buildings. • Providing case study-based data on water consumption of vernacular structures. • Addressing the effect of personnel meals on the water footprint of structures. • Showing the relationship between structural types and cleaner production. [ABSTRACT FROM AUTHOR]

Abstract To aid the design of buildings with lower environmental impacts, it is important to be able to rapidly compare the predicted impacts and costs of design alternatives at early stages of the design process when many influential decisions are made. At the same time, it is also important to preserve design flexibility in order to better accommodate diverse project constraints and goals. This paper presents the first use of an early-design, probabilistic life cycle assessment (LCA) method to identify and summarize the characteristics of buildings with near-optimum or "quasi-optimum" life cycle impacts and costs. Two design guidance methods are explored: sequential specification – in which influential attributes are iteratively identified and specified – and genetic optimization. The efficiency of these methods are compared using information entropy to quantify the flexibility of the probabilistic design as it is refined. Genetic optimization is found to be more efficient than sequential specification because it leads to more optimal solutions with greater flexibility. Quasi-optimum designs are identified and analyzed to determine which attributes must be specified in a particular way and which attributes have more flexible ranges to achieve a given percentage of the optimum reduction in impacts and costs. It is found that quasi-optimum designs representing 75% of these optimum reductions can be associated with a 40% increase in design flexibility over optimized designs. Twelve cases are presented that explore the influence of climate, analysis period, energy-related impact factor variability, and optimization weighting of impacts and costs on quasi-optimum designs. Graphical abstract Image 1 Highlights • Genetic optimization provides more efficient guidance than sequential specification. • Quasi-optimum alternatives identified and summarized to increase design flexibility. • Critical vs. flexible design parameters identified in twelve case studies. • Most geometrical and occupant-related attributes are flexible in all cases. • Flexibly of systems-related parameters varies by case. [ABSTRACT FROM AUTHOR]

Abstract Design for Deconstruction (DfD) is a design approach that enables reuse of durable building components, including structural materials, across multiple building projects. An important DfD strategy is the use of pre-fabricated modular building assemblies and reversible connections, in contrast to cast-in-place composite systems that must be demolished at building end-of-life. In this paper we evaluate a novel DfD flooring system consisting of pre-cast concrete planks and clamped connections. Life cycle energy and environmental benefits of using this DfD system are evaluated using life cycle assessment (LCA) across four impact categories of interest to the building and construction sector including fossil fuel use, greenhouse gas emissions, respiratory effects, and photochemical smog formation. Eight different DfD building designs are tested for 0–3 reuses compared with a traditional structural design, with energy and environmental benefits accruing from substitution of avoided structural materials. Designs reflect expected loads and current code requirements, while the additional time required for deconstruction of DfD buildings is accounted for in the construction schedules. Monte Carlo simulation is used to generate 95% confidence intervals for the results. In general, DfD designs result in higher initial (original building) energy use and environmental impacts, but have statistically lower impacts than traditional designs if flooring planks are used at least once. Reusing planks three times as designed decreases impacts by a mean value of of 60–70%, depending on the building configuration and impact category. Energy use and environmental impacts from eventual recycling and/or disposal of the reusable components are significant, and emphasize the relative benefits of reuse over recycling. Highlights • Direct reuse of building materials is enabled by Design for Deconstruction (DfD). • DfD clamped precast composite flooring systems can replace cast-in-place decking. • Life cycle assessment reveals energy and environmental savings for DfD with reuse. • Actual disassembly and reuse practices depend on location and market forces. [ABSTRACT FROM AUTHOR]

All-electric boilers and air source heat pumps are both powered by electric energy. However, each kWh of heat that is produced implies higher electric consumption in the former. Therefore, as a consequence of financial issues, users of all-electric boilers might afford the substitution of this heating device by an air source heat pump (ASHP). In this paper, a particular facet of this replacement is analyzed, its environmental impact, providing with a deeper insight in the consequences of this substitution. A life cycle assessment of the replacement of an all-electric boiler by an ASHP is described, using 11 environmental impact categories and three different heat emitters, such as underfloor heating, low temperature radiators and conventional radiators. As a consequence of this analysis, it has been found that, in most of the categories, the energy savings from the replacement compensate the environmental impact of the ASHP. This trend is more evident with underfloor heating than radiators. Additionally, the environmental amortization of this replacement has also been analyzed. The results of this study show that the environmental amortization can be achieved by an ASHP with underfloor heating during a conservative lifespan of 10 years in all the impact categories. Other heat emitters may require between 33% and 45% more time to reach the environmental amortization. [ABSTRACT FROM AUTHOR]

In this study, the environmental impact of each material is proposed to enable effective greenhouse gas reduction design. Therefore, 6 major environmental impacts were analyzed for 29 buildings of school facilities using the self-developed building life cycle evaluation tool. As a result of the analysis, in the production stage of the six major environmental impacts, the top five materials consisting of structural materials such as concrete, cement, and rebar accounted for GWP 83.3%, ODP 94.4%, ADP 91.6%, AP 77.9%, EP 76.3%, and POCP 93.9%. In addition, as a result of evaluating the potential for reducing environmental impact by replacing voluntarily with concrete, cement, and insulation materials that have been voluntarily certified by the Environmental Product Declaration or low-carbon certification by companies, GWP was analyzed to be reduced by 11.9%, ODP 38.96%, ADP 13.21%, AP 1.18%, EP 5.53%, and POCP 50.61%.". Through this study, it shows the effect of material selection on greenhouse gas and suggests that designers' material selection ability can be an efficient alternative for eco-friendly design for global carbon neutrality. • In this paper, the life cycle evaluation of school facilities was conducted. • The environmental impact of each stage was compared. • A list of materials with a large environmental impact was derived at the production stage. • The extracted materials were analyzed by replacing them with EPD or low-carbon certified materials. [ABSTRACT FROM AUTHOR]

In a previous work, the authors of this paper proposed a new modular living wall made with expanded cork agglomerate, fully describing the designing process and discussing the overall mechanical performance. It was then shown that several key environmental and functional requirements were met by favouring the use of insulation cork board (ICB), a thermal insulation material with low environmental impact and good water retention. In this paper, the authors have extended the characterization of that living wall system to assess its performance under real conditions, with different plant species, geographical orientations and seasons. For this purpose, a prototype was built with four façades, facing north, south, east, and west. The area of façade covered by vegetation and the carbon sequestration provided by two different plant species were then monitored for over a year. Annual values of carbon uptake, experimentally determined, were further used to update an environmental life cycle model of the system. The results suggest that this modular living wall performs well in terms of plant development and carbon sequestration, with Festuca glauca showing a higher cumulative carbon uptake and a higher percentage of façade coverage than Thymus pulegioides , regardless of the geographical orientation and season. This essentially results from the greater amount of biomass produced by Festuca glauca and its hanging behaviour. It was also concluded that this new modular living wall is an eco-friendly choice, when assessed from a life cycle perspective, since it has a negative carbon balance over its life cycle (22.7 kg CO 2 eq per square meter). • Innovative cork-based living wall tested under real conditions. • Annual carbon uptake up to up 371 g C/m2 experimentally confirmed. • Negative carbon balance of 22.7 kg CO 2 eq/m2 over the life cycle. • Modular living wall with improved environmental performance. [ABSTRACT FROM AUTHOR]

Building renovation is urgently required to decrease the energy consumption of the existing building stock and reduce greenhouse gas emissions coming from the building sector. Selecting an appropriate renovation strategy is challenging due to the long building service life and consequent uncertainties. In this paper, we propose a new framework for the robust assessment of renovation strategies in terms of environmental and economic performance of the building's life cycle. First, we identify the possible renovation strategies and define the probability distributions for 74 uncertain parameters. Second, we create an integrated workflow for Life Cycle Assessment (LCA) and Life Cycle Cost analysis (LCC) and make use of Sobol' indices to identify a prioritization strategy for the renovation. Finally, the selected renovation scenario is assessed by metamodeling techniques to calculate its robustness. The results of three case studies of residential buildings from different construction periods show that the priority in renovation should be given to the heating system replacement, which is followed by the exterior wall insulation and windows. This result is not in agreement with common renovation practices and this discrepancy is discussed at the end of the paper. Image 1 • Changing only the heating system is more efficient than doing a full renovation. • Social and economic parameters are crucial during the probabilistic assessment. • Heating system is the most influential parameter in building renovation. • Global sensitivity analysis is performed using Sobol' indices. • Uncertainty quantification is performed using polynomial chaos expansion. [ABSTRACT FROM AUTHOR]

The reticulated dome structure is a system composed of linear elements arranged in such a way that the forces are transferred in a three-dimensional manner. These dome structures require less amount of materials to be built when compared to continuous surface domes, thereby, reducing the embodied energy of the structure, i.e., the energy used in the manufacture and transportation of materials. However, selecting materials with high embodied energy can significantly impact the energy use and environmental impact of reticulated domes. In line with sustainable construction practices, use of materials that reduces overall embodied energy of the structure is desirable. This paper compares the embodied energy and related environmental impacts of four alternative materials used to construct these structures namely aluminum, steel, laminated veneer lumber, and laminated bamboo. To estimate the quantities required to construct the dome structure, a finite element-based structural analysis software, MSC Patran/Nastran was used. Using the estimated quantities of alternative materials, detailed life cycle inventory was performed using GaBi software. The results of the environmental impact assessment show that aluminum and steel have higher embodied energy when compared to the other two materials. Furthermore, the results show that bamboo has a negative global warming potential outperforming laminated veneer lumber option. Additionally, a simplified life cycle analysis tool, Athena Impact Estimator, was used to compare results obtained from GaBi analysis. Overall, the results indicate that the use of alternative materials can significantly reduce the embodied energy and provide environmentally sound options to address the current environmental challenges. [ABSTRACT FROM AUTHOR]

Both the construction and use of buildings cause significant environmental pressures. The greenhouse gas (GHG) emissions imposed by buildings have been studied rather extensively, but less is known about other impacts. Still, climate change is only one harmful impact driven by buildings. Furthermore, no studies exist about how the other impacts are correlated with GHG emissions in the building context, and thus to what extent GHGs could be utilized as a more general environmental performance indicator. This paper fills these gaps by presenting a life cycle assessment of the pre-use phase of a modern concrete-element residential building with a very comprehensive life cycle inventory (LCI). The focus of the study is on the comparison of the accumulation of different environmental impacts relative to GHGs. The accumulation is analyzed from two perspectives common to building LCAs: building systems and different construction materials. The ReCiPe midpoint assessment method is utilized to reach wide impact category coverage. The study shows how GHGs act as a relatively good indicator for eight impact categories, but not for the others. The study also depicts that a very high coverage in the LCI must be reached to capture the majority of the different impacts. Many materials and building systems are considered non-relevant and are often excluded from building LCAs, which are in fact of great importance in many impact categories. [ABSTRACT FROM AUTHOR]

This paper assesses the environmental impacts of conventional and modular housing by applying measures of 'absolute environmental sustainability'. It seeks to determine 1) the environmental performance of typical housing across different geographic boundaries, in this case Australia and Denmark, to explore whether such buildings can be deemed to achieve absolute sustainability within the planetary boundaries, and how factors related to location impact this, and 2) whether modular buildings perform better in terms of absolute environmental sustainability. The research measures lifecycle environmental performance of four case study buildings (conventional and modular, in Australia and Denmark), across seven impact categories. Normalisation references are determined based on the carrying capacity of earth by allocating a percentage of its limited resources to housing. A building would be considered to achieve absolute environmental sustainability if its environmental burden is less than its allocated share of the carrying capacity. The results found that none of the four buildings met this criterion. The two Australian buildings exceeded their allocated capacity in six of the seven impact categories, with figures of 700–36,000% above capacity. The two Danish buildings did so in five of the seven categories, with figures of 200–3700% above. Modular buildings generally had lower environmental impacts across all categories, but still exceeded their allocations. The primary contributor was the operational phase of the buildings' lifecycle. However, even when this was excluded, all four buildings' impacts remain above their allocated limits, suggesting that environmental reductions are necessary across both embodied and operational stages. • Environmental impacts of conventional and modular housing, applying measures of 'absolute environmental sustainability'. • No studied case satisfied allocated absolute environmental sustainability measure across all included impact categories. • Modular case study building designs perform better, relatively compared to the conventional counterpart. • Comparison between countries helps highlight different issues in need of focus. • Economic household or dwelling allocation performed should be further developed. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents for the first time the results of a full life cycle assessment (LCA) 1 [1] Life cycle assessment. study for the three most common types of house in the UK: detached, semi-detached and terraced. All life cycle stages are considered, including house construction, use and demolition after 50 years. The results indicate that the use stage has the largest contribution to most environmental impacts. For example, the global warming potential (GWP) 2 [2] Global warming potential. over the 50-year lifetime of the detached house is 455 t of CO2 eq.; 374 t CO2 eq. of the semi-detached; and 309 t CO2 eq. of the terraced house. Around 90% of the GWP is from the use, 9% from construction (embodied carbon) and 1% from the end-of-life waste management. A similar trend is noticed for all other impacts. Recycling the building materials at the end of life leads to an overall reduction of the impacts. For instance, the GWP reduces by 3% for the detached and semi-detached houses (to 441 t of CO2 eq. and 363 t CO2 eq., respectively) and by 2% (to 302 t CO2 eq.) for the terraced house. The main environmental benefit is from reusing the bricks and recycling the aggregates. At the housing sector level, the total GWP is 132 million tonnes of CO2 eq. per year with the semi-detached houses contributing 40%, terraced 37% and detached houses 27%. Over the 50-year lifetime, the total GWP from the sector is nearly 6.6 billion tonnes of CO2 eq. The results also highlight the importance of decisions made in the design and construction stages as they determine the impacts of the house in the use and end-of-life stages. [Copyright &y& Elsevier]

This paper presents a matrix to select sustainable materials for buildings in Sri Lanka, taking into consideration environmental, economic and social assessments of materials in a life cycle perspective. Five building elements, viz., foundations, roofs, ceilings, doors and windows, and floors are analyzed based on materials used for these elements. Environmental burdens associated with these elements are analyzed in terms of embodied energy and environmental impacts such as global warming, acidification and nutrient enrichment. Economic analysis is based on market prices and affordability of materials. Social factors that are taken into account are thermal comfort, interior (aesthetics), ability to construct quickly, strength and durability. By compiling the results of analyses, two building types with minimum and maximum impacts are identified. These two cases along with existing buildings are compared in a matrix of environmental, economic and social scores. Analysis of the results also indicates need for higher consideration of environmental parameters in decision-making over social and economic factors, as social and economic scores do not vary much between cases. Hence, this matrix helps decision-makers to select sustainable materials for buildings, meaningfully, and thus helps to move towards a more sustainable buildings and construction sector. [Copyright &y& Elsevier]

This paper provides a detailed analysis of life cycle assessment (LCA) results of different building components (e.g. wooden wall, concrete roof) on different levels of simplification (from a comprehensive LCA including all materials and processes to the fully reduced component including only the main materials remaining in the component). The main objective is the determination of the relevance of materials and processes often neglected in simplified LCA of building components which aim at providing results of similar quality as comprehensive assessments with less effort. The studied simplifications are categorised in transportations of the building materials from the factory gate to the building site, some ancillary materials which are not obvious in the component, the building process itself and the associated cutting waste. The results show that transports and ancillary materials are of relevance while the building process and the cutting waste can be neglected. The heavier the used materials and the longer the transport distances the bigger is the influence of transports on the LCA results. The influence of the ancillary materials is highest for wooden constructions as a lot of screws nails and other connectors are essential. [Copyright &y& Elsevier]

The environmental impact of buildings is commonly quantified through life cycle assessment (LCA). Because of practical constraints (e.g. data limitations, timing, complexity), various simplifications are often made. However, the impact of certain simplifications is not clear. Due to the particular geometry of a building, the execution of renovation measures typically entails environmental impacts due to material and energy use at building envelope interfaces which are not considered in simplified LCAs. Hence, this paper examines the effect of a one-dimensional approach as simplification strategy on the environmental impact regarding material use and operational energy use for different renovation scenarios applied to a residential high-rise building. A simplified LCA is therefore compared with a detailed LCA that considers the real building design. First, the effect of linearly scaling the environmental impact based on a one square meter approach is confronted with the real building complexity. Then, the impact of neglecting thermal bridges on the operational energy use is analysed. Finally, both results are combined to evaluate the overall effect on the environmental life cycle impact. The simplifications entail an underestimation of the environmental material use, operational energy use and life cycle impact of 6–49%, 10–36% and 10–30%, respectively. The underestimation of the life cycle impact highly correlates with the operational energy use because of the significant contribution of the operational energy use to the environmental life cycle impact, namely 81–99%. As a result, the effect of simplifications concerning material use on the total life cycle impact is found to be negligible. − The effect of a 1D approach as simplification strategy in LCA is studied − A detailed LCA of an envelope renovation is applied to a multi-family building − A 1D LCA underestimates the total environmental life cycle impact by 10–30% − Including thermal bridges increases the environmental life cycle impact by 9–29% − The additional material use compared to a 1D LCA has a negligible contribution [ABSTRACT FROM AUTHOR]

Abstract: Wooden type of housing is ubiquitous in Japan. It is the main structure for housing; however, due to the increase in residential developments, steel reinforced concrete houses are also on the rise. This paper assesses the environmental impacts of these two types of construction. An evaluation of the two types of construction in terms of energy usage and air emissions is done. A comparison of the damage costs due to the generated emissions is also considered. Four types of emissions generated are evaluated, namely carbon emissions (CO2), nitrogen oxides (NO x ), sulfur oxides (SO x ) and suspended particulate matter (SPM). The life cycle of the two different housing construction types is traced and environmental impacts are determined. External costs are also calculated. Furthermore, different improvement assessment scenarios are simulated to ascertain several emission reduction possibilities. The study looks into the emitted emissions from the housing construction to its final disposal of a typical residential development in Saga, Japan. Results show that much of the environmental impacts from building a house are on the Global Warming Potential due to high carbon emissions. Moreover, the construction phase generated the highest pollutant emissions from nitrogen oxides, sulfur oxides and suspended particulate matter. Steel reinforced concrete (SRC) construction has a higher environmental impact compared to the wooden type of housing construction. A longer design life for a residential house gives a reduction of about 14% in carbon emissions. Using solar energy for the operation phase has gained a reduction of 73% in the total life cycle carbon emissions. [Copyright &y& Elsevier]

Abstract: This paper constitutes a continuation of “Alternative scenarios analysis concerning different types of fuels used for the coverage of the energy requirements of a typical apartment building in Thessaloniki, Greece. Part I: fuel consumption and emissions”. It is concerned with the application of life cycle analysis (LCA) methodology to the model of the apartment building determined in Part I. The examination here includes emissions of light heating oil EL refining, transportation and combustion, of natural gas transportation and combustion and of electricity generation and use (lignite, natural gas, diesel oil and kerosene originated). All data used were collected from a typical power station in Greece. [Copyright &y& Elsevier]

Abstract: Since buildings have considerable impacts on the environment, it has become necessary to pay more attention to environmental performance in building design. However, it is a difficult task to find better design alternatives satisfying several conflicting criteria, especially, economical and environmental performance. This paper presents a multi-objective optimization model that could assist designers in green building design. Variables in the model include those parameters that are usually determined at the conceptual design stage and that have critical influence on building performance. Life cycle analysis methodology is employed to evaluate design alternatives for both economical and environmental criteria. Life cycle environmental impacts are evaluated in terms of expanded cumulative exergy consumption, which is the sum of exergy consumption due to resource inputs and abatement exergy required to recover the negative impacts due to waste emissions. A multi-objective genetic algorithm is employed to find optimal solutions. A case study is presented and the effectiveness of the approach is demonstrated for identifying a number of Pareto optimal solutions for green building design. [Copyright &y& Elsevier]

Abstract: The main research objective was establishing a simple but reliable methodology for the building design stage that would yield environmentally optimal buildings. A three-step methodology is proposed: (1) design variable grouping—four distinct groups were recognized according to their stage of major influence (production and construction, operational energy, maintenance to demolition, and an Integrated Group relevant to several life cycle stages), (2) generating the within group optimization methodology, and (3) integration. This paper presents the methodology developed for the grouping procedure, and its testing and application on a simple generic office module. Sensitivity analysis highlights the significance of electricity production fuel. [Copyright &y& Elsevier]

The life cycle assessment (LCA) methodology is used in this paper to assess the environmental impacts of residential ventilation units over a 50 year life cycle in Finland. Quantifying the consumption of the energy and material resources during the life cycle permits the estimation of the harmful emissions into the environment (air, water and soil) and the potential changes in the environment (climate change, acidification and ozone production). Two different ventilation units are evaluated, both of which include air-to-air energy exchangers. The research demonstrates that a residential ventilation unit, with a function of providing 50l/s of outdoor ventilation air, but not heating the air, has a net positive impact on the environment when it is equipped with a air-to-air energy exchanger with an effectiveness greater than 15%. The greater the effectiveness, the greater the positive impact on the environment. [Copyright &y& Elsevier]

During the last decades there has been an increasing interest in environmental assessments of the built environment. As a result, we can find several qualitative and quantitative assessment tools. With an increasing understanding of cities and the built environment as systems metabolising matter and energy, the use of quantitative tools are expected to increase, making it relevant to ask for their status of development. Aiming to give an overview of the present status of quantitative tools, as a basis for further research and development, this paper describes and compares five different tools for quantitative environmental assessment of the built environment. [Copyright &y& Elsevier]

Building energy retrofits have been identified as key to realizing climate mitigation goals in Canada. However, retrofit solutions that only produce greenhouse gas emission savings can place economic burdens on residential building owners and hinder the community penetration of building energy retrofitting projects. Therefore, investigating trade-offs between environmental and economic impacts of retrofitting is essential to identify optimal retrofit strategies that can produce emissions savings while delivering economic benefits for the stakeholders. This paper proposes a community-level building energy retrofit evaluation framework for residential buildings. The proposed framework evaluates building energy retrofits using a multi-objective optimization approach that accounts for associated life cycle economic and environmental impacts. Life cycle CO 2 emissions were selected as the indicator for environmental performance. The net present value of the cash flows involved in a given retrofit project throughout the project life cycle was selected as the economic performance indicator. Building energy simulation results were combined with economic and environmental impact data to quantify these performance indicators. The performance results were used to identify Pareto-optimal retrofit solutions. The results indicate that retrofitting existing residential buildings can produce considerable emission reductions (up to 245.1 tonCO 2 eq/residence) and cost savings (up to 12,900 $/residence). Moreover, retrofit packages should prioritize upgrading building envelope insulation and space heating systems. This study introduces a decision support tool for community-level retrofit planners that can account for life cycle environmental and life cycle economic performance of retrofitting while fulfilling capital investment constraints. • Energy retrofits were evaluated using life cycle assessment and cost analysis. • The trade-offs between life cycle emissions and costs were explored. • Optimal retrofit packages for residential buildings were identified. • Natural gas heated buildings should be prioritized for retrofitting. • Strategies for promoting community-level retrofit programs were proposed. [ABSTRACT FROM AUTHOR]

The global market trend for Vacuum Insulation Panels (VIPs) is projecting a significant increase in their uptake in the construction sector. This is mainly due to the uniquely high-performance properties of the ultra-thin insulation materials. This uptake, however, can potentially be hindered by the VIPs' higher cost and environmental impacts when compared with conventional insulation materials. This paper, for the first time, presents a detailed evaluation of the environmental impact of the most common type of VIPs currently used in different applications with a focus on alternating the core material as the main contributing component to their footprint. Pyrogenic silica, glass fibre, expanded polystyrene, aerogel and a silica/sawdust hybrid core were analysed from cradle to gate. The study, on a comparative basis, demonstrates the sensitivity of the various environmental impact categories to the internal vacuum pressure and the subsequent thermal conductivity values. The results show a lower environmental impact for glass fibre and low density expanded polystyrene compared to the other alternatives. Pyrogenic silica, the most common core material, had the highest environmental impact out of the core materials considered. The higher environmental impacts of pyrogenic silica suggest that measures such as the recycling of the core material alongside the deployment of eco-friendlier manufacturing techniques should be considered if the material is to compete environmentally with the other alternative materials. Image 1 • Environmental impact of different VIP core materials was compared for the first time. • Cradle to gate approach has been adopted for the analyses in accordance with EN15804. • Sensitivity analyses conducted for internal vacuum pressure and core material EPDs. • Pyrogenic silica had the highest environmental impact of the core materials studied. • Glass fibre had the lowest environmental impact for vacuum pressures lower than 10Pa. [ABSTRACT FROM AUTHOR]

Buildings contribute a significant portion of global greenhouse gas emissions and have the potential for large-scale impact reductions. Reducing the whole-life impacts of buildings is critical for creating a net-zero carbon built environment. For this to be achieved, the whole-life carbon impacts of design decisions must be considered during the building design process. A systematic review of academic literature was conducted to assess how life cycle assessment (LCA) is incorporated at various stages of the building design process, and what improvements are needed to support net-zero carbon design. The review compiled 274 papers that were published up to the end of 2019, of which 108 were subject to detailed review following screening. The review found that LCA is generally used late in the design process, when it is too late to greatly influence the design. Incorporating LCA with either building information modelling or life cycle costing is seen to have the same challenges as undertaking a traditional LCA. Parametric methods show promise for design development, but tools and algorithms require further verification and regionalisation to be implemented throughout industry. The use of benchmarks, target values and other pre-populated information can be used to incorporate life-cycle thinking without the need to undertake a detailed LCA. The review has demonstrated that LCA continues to face barriers, in both methods and practice, preventing its ability to guide early-stage design decisions and have a large impact on the environmental performance of buildings. • Life cycle thinking is needed to produce a net-zero built environment. • Reactive methods are predominantly used to conduct environmental assessment. • Reactive methods assess building designs after completion. • Proactive methods can guide decisions during early-stage design. • Proactive methods are a viable means of reducing whole-life impacts in buildings. [ABSTRACT FROM AUTHOR]

Renovating buildings can be an important way to reduce the environmental impact of the outdated building stock. In reality the environmental aspect is rarely the sole concern for making renovation decisions and both the environmental and financial aspect need to be taken into account for viable and comprehensive renovation solutions to arise. This paper researches the environmental and financial impact of façade renovation strategies designed for change through life cycle analysis (LCA) and life cycle cost assessment (LCC) respectively. Its goal is to propose a methodology to obtain façade renovation strategies that are optimal from both the environmental and financial viewpoint and to simultaneously highlight the similarities and the differences between an approach based on LCA and on LCC. The methodology composes façade renovation strategies step-by-step by evaluating the design variables of a façade: renovation system, material combination, insulation thickness and window type. Environmental-financial optimal solutions of the design variables are determined using the Pareto front. The eventual Pareto front consists of environmental-financial optimal façade renovations fulfilling the predetermined boundary conditions. The results show that material and construction choices that are both financially and environmentally beneficial can be made. For the environmental impact the operational energy has the largest contribution and energy renovation measures will often be beneficial. For the life cycle cost the investment cost is the most important and energy efficiency measures will only pay off to a certain extent. [ABSTRACT FROM AUTHOR]

Buildings are responsible for a considerable portion of the embodied and operational CO 2 emitted by human activities. Some building attributes have taken on the mantle of "environmentally preferable". Through a systematic literature review, this paper investigates if the literature on whole building Life Cycle Assessments (LCA) confirms some environmental assumptions that are perceived as always truthful, e.g. (i) "wood is better than concrete and steel", (ii) "renovation is preferable to demolishing and building anew", and (iii)"operational loads are more intensive than embodied loads". The search also allowed to trace if advanced methodological modelling in LCA brings new insights into the mentioned perceptions. The assessment of over 250 case studies pointed that LCAs applied to complex systems, such as a building, embed crucial issues to be modeled, and rules of thumb lose veracity. Furthermore, as LCA incorporates deepened mathematical models, outcomes become less predictable, and paradigms should be interpreted with care. • In complex systems - such as buildings – environmental paradigms lose veracity. • As sophisticated models are incorporated in LCA, outcomes become less predictable. • Practitioners should add mathematical depth to LCA studies to bring new insights. • Transparency in methodological choices is consistently missing. [ABSTRACT FROM AUTHOR]

There is increasing interest in the study of Life Cycle Assessment (LCA) of buildings, which entails an estimate of the potential environmental impacts and resource use of buildings. This is driven by increasing awareness of the environmental impact of buildings, as well as the emergence of enabling tools for their assessment. There are review articles on building LCA (see Table 1) but none focuses on the challenges of building LCA, ongoing studies and potential solutions to address the challenges. The aim of this paper is to provide an up-to-date systematic review of life cycle assessment of buildings, and to discuss the major challenges in building LCA, ongoing studies and potential solutions to resolve the identified issues. The methodology involves a detailed literature review to provide an overview of existing studies in building LCA, and a systematic selection and study of review articles/books to investigate the benefits and challenges of building LCA. A summary of the research outputs and recommended further studies on building LCA are outlined in the conclusion section. The major challenges in building LCA were identified as data intensity and quality, subjectivity in environmental impact characterization and valuation, inadequate definition of functional units, assumptions for building life span and service life, lack of procedure for system boundaries, lack of uncertainty analysis, and limitation as a decision-making tool. In addition to discussing ongoing studies to address the issues, this study also proposes research trajectories to resolve the major challenges identified in building LCA. • Provides an up-to-date statistic of the patterns of growth of interest in building LCA using a bibliometric approach. • Presents a review of current research on building LCA to highlight the trends and opportunities in the topic. • Discusses top issues in building LCA and proposes research trajectories to resolve the identified issues. • Provides a summary of existing review studies on LCA of buildings and their individual goals to enable easy references. •Uses a systematic approach to provide an up-to-date review of life cycle assessment of buildings. [ABSTRACT FROM AUTHOR]

A common practice in Life Cycle Assessment (LCA) of buildings is to consider a default value for their lifespans. However, statistical data show longer lifespans and it is proved that the higher they are the lower the environmental impacts. Therefore, the common practice of considering a default value for lifespans in buildings LCA involves a high risk of programmed obsolescence in the building sector. This paper addresses a new approach to estimate buildings lifespans based on their structures durability. We use a comparative case study of refurbishment vs. new construction to illustrate its use. The lifespans of the refurbished and the new buildings are estimated by applying degradation models of reinforced concrete structures. Two thermal performance levels are evaluated: standard and passive, in both alternatives, the refurbished and the new building. Comparisons are also made with other approaches to determine buildings lifespans based on default value and statistical data. Results show that a new building can have a lifespan more than six times longer than a refurbished one. A strong dependence of LCA results on the lifespan is revealed. Its value can alter the order of preference of the solutions when comparing alternatives and therefore default value approaches are unadvisable. There is in our case study a 11% potential of environmental improvement for new buildings behaviour by changing current practices and extending buildings' lifespan up to their physical limit. • The lifespans of a new and an existing building of the 50s can differ up to 176 years. • The physical durability of new buildings can be up to 210 years. • Extending the service life of new buildings can reduce annual impacts up to 11%. [ABSTRACT FROM AUTHOR]