Building renovation is urgently required to reduce the environmental impact associated with the building stock. Typically, building renovation is performed by envelope insulation and/or changing the ...fossil-based heating system. The goal of this paper is to provide strategies for robust renovation considering uncertainties on the future evolution of climate, energy grid, and user behaviors, amongst others by applying life cycle assessment and life cycle cost analysis. The study includes identifying optimal renovation options for the envelope and heating systems for building representatives from all construction periods that are currently in need of renovation in Switzerland. The findings emphasize the paramount importance of heating system replacements across all construction periods. Notably, when incorporating bio-based insulation materials, a balance emerges between environmental impact reduction and low energy operation costs. This facilitates robust, equitable, and low-carbon transformations in Switzerland and similar Northern European contexts while avoiding a carbon spike due to the embodied carbon of the renovation.
To meet the European climate goals in the building sector, a holistic optimization of embodied greenhouse gas (GHG) emissions using the method of life cycle assessments (LCA) are necessary. The early ...design stages have high impact on the final performance of the buildings and are characterized by high uncertainty due to the lack of information and not yet taken decisions. Furthermore, most current LCA approaches based on Building Information Models (BIM) require high expertise and experience in both BIM and LCA and do not follow an intuitive visualization approach for other stakeholders and non-experts. This paper presents a novel design-decision-making approach for reducing embodied GHG emissions by interactive, model-based visualizations of uncertain LCA results. The proposed workflow is based on open BIM data formats, such as Industry Foundation Classes (IFC) and BIM Collaboration Format (BCF), and is developed for decision support for non-LCA experts in the early design stages. With the help of a user study, the prototypical implementation is tested by 103 participants with different levels of experience in BIM and LCA based on a case study. We evaluate the proposed approach regarding the support of open BIM data formats, different LCA visualization strategies, and the intuitiveness of different approaches to visualizing uncertain LCA results. The user study results show a broad acceptance and need for open BIM data formats and model-based LCA visualization but less for visualizing uncertainties, which needs further research. In conclusion, this interactive, model-based visualization approach using color coding supports non-LCA experts in the design decision-making process in early design stages.
As the high greenhouse gas (GHG) emissions caused by the construction and real estate sector receive more attention, more and more countries include an environmental assessment of buildings based on ...Life Cycle Assessment (LCA) in their building regulations. Sweden introduced mandatory climate declarations in January 2022, for example. To support stakeholders in conducting the climate declarations and using the results to reduce GHG emissions, user-friendly tools for early planning stages are needed. The aim of this study is to develop and test a framework for user centric development of such tools. The framework builds on three steps; 1) interviewing stakeholders to define tool requirements, 2) developing a prototype tool according to the requirements, and 3) evaluating it based on user feedback. We developed and tested the framework in the Swedish context to provide a blueprint applicable to other countries and contexts. The primary target users are architects with computational design experience but also engineers and real estate developers working in early phases. The results show that the users’ expectations can be met when the requirements are integrated from the very beginning. In the current version, the developed building LCA tool only targets the embodied GHG emissions from the production and construction phase of the building, but it could be extended to include further life cycle phases in the future.
Digital tools based on Building Information Modelling (BIM) provide the potential to facilitate environmental performance assessments of buildings. Various tools that use a BIM model for automatic ...quantity take-off as basis for Life Cycle Assessment (LCA) have been developed recently. This paper describes the first application of such a BIM-LCA tool to evaluate the embodied global warming potential (GWP) throughout the whole design process of a real building. 34 states of the BIM model are analysed weekly. The results show that the embodied GWP during the design phase is twice as high as for the final building. These changes can be mainly attributed to the designers' approach of using placeholder materials that are refined later, besides other reasons. As such, the embodied GWP is highly overestimated and a BIM-based environmental assessment during the design process could be misleading and counterproductive. Finally, three alternatives to the established automatic quantity take-off are discussed for future developments.
•First application of a BIM-LCA approach throughout the design process of a real building•Tracking of design decisions using 34 fixed states of the continuously evolving BIM model•Identification of limitations of the current BIM-LCA approach•Proposals for future effective environmental performance improvement during the design phase
Target values for creating carbon budgets for buildings are important for developing climate-neutral building stocks. A lack of clarity currently exists for defining carbon budgets for buildings and ...what constitutes a unit of assessment—particularly the distinction between production- and consumption-based accounting. These different perspectives on the system and the function that is assessed hinder a clear and commonly agreed definition of ‘carbon budgets’ for building construction and operation. This paper explores the processes for establishing a carbon budget for residential and non-residential buildings. A detailed review of current approaches to budget allocation is presented. The temporal and spatial scales of evaluation are considered as well as the distribution rules for sharing the budget between parties or activities. This analysis highlights the crucial need to define the temporal scale, the roles of buildings as physical artefacts and their economic activities. A framework is proposed to accommodate these different perspectives and spatio-temporal scales towards harmonised and comparable cross-sectoral budget definitions.Policy relevanceThe potential to develop, implement and monitor greenhouse gas-related policies and strategies for buildings will depend on the provision of clear targets. Based on global limits, a carbon budget can establish system boundaries and scalable targets. An operational framework is presented that clarifies greenhouse gas targets for buildings in the different parts of the world that is adaptable to the context and circumstances of a particular place. A carbon budget can enable national regulators to set feasible and legally binding requirements. This will assist the many different stakeholders responsible for decisions on buildings to coordinate and incorporate their specific responsibility at one specific level or scale of activity to ensure overall compliance. Therefore, determining a task specific carbon budget requires an appropriate management of the global carbon budget to ensure that specific budgets overlap, but that the sum of them is equal to the available global budget without double-counting.
Life-Cycle Assessments (LCA) have become a common tool of decision support in the built environment regarding environmental impacts. The goal of this study is to investigate the influence of ...different LCA approaches and system boundaries on decision support regarding circular design strategies. Three different ways of applying attributional LCA (ALCA) and one consequential LCA (CLCA) are assessed using a case study of a wooden beam with either virgin or reclaimed timber. While the conclusions are not readily scalable, the case study's results indicate that using reclaimed material is environmentally beneficial when applying ALCA. However, when applying CLCA the reclaimed material performs worse than the virgin material. This highlights the potential pitfalls of scaling up solutions based on LCA results without considering the broader consequences. While the current ALCA approach is useful for declarations, it may not provide comprehensive decision support for driving a transition in the built environment.
•Investigation of decision support influence of Life Cycle Assessment choices.•Comparative case study of wooden beam design, using virgin or reclaimed timber.•Attributional LCA with allocation, indicated environmental benefits using reclaimed timber.•Consequential LCA with system expansion and substitution flips benefit conclusion.•Important to consider dynamics and changes beyond the attributional system boundary.
The vast majority of scientists and policy makers agree that environmental impacts of buildings need to be reduced significantly, and that Life Cycle Assessment (LCA) is a methodology well suited to ...support this. The importance of evaluating potential improvements to the environmental life cycle performance of buildings in early design stages is widely acknowledged; the wide application of LCA during design however, is restrained by the great uncertainty in design and material decisions at this stage. To support decision making in the early design stage, we propose an approach using Building Information Modeling (BIM) to assess a wide range of construction options and their embodied environmental impact. We use a conceptual BIM model to evaluate a variety of material compositions for different building elements and the potential contribution of elements to the total embodied impact of the building design. The BIM-integrated approach enables identification of design specific hotspots which can be visualized on the building model for communication of LCA results and visual design guidance.
•We propose a new approach using visual scripting to connect Life Cycle Assessment (LCA) and Building Information Modeling (BIM) for the early design stage.•We use a conceptual BIM model to evaluate multiple construction options and the contribution of different building elements to total embodied impact of the building.•The BIM-integrated approach enables us to identify and visualize design specific hotspots and improvement potential for reducing the building’s embodied impact.
Purpose
Life cycle assessment (LCA) has not been widely applied in the building design process because it is perceived to be complex and time-consuming. There is a high demand for simplified ...approaches that architects can use without detailed knowledge of LCA. This paper presents a parametric LCA approach, which allows architects to efficiently reduce the environmental impact of building designs.
Methods
First, the requirements for design-integrated LCA are analyzed. Then, assumptions to simplify the required data input are made and a parametric model is established. The model parametrizes all input, including building geometry, materials, and boundary conditions, and calculates the LCA in real time. The parametric approach possesses the advantage that input parameters can be adjusted easily and quickly. The architect has two options to improve the design: either through manually changing geometry, building materials, and building services, or through the use of an optimization solver. The parametric model was implemented in a parametric design software and applied using two cases: (a) the design of a new multi-residential building, and (b) retrofitting of a single-family house.
Results and discussion
We have successfully demonstrated the capability of the approach to find a solution with minimum environmental impact for both examples. In the first example, the parametric method is used to manually compare geometric design variants. The LCA is calculated based on assumptions for materials and building services. In the second example, evolutionary algorithms are employed to find the optimum combination of insulation material, heating system, and windows for retrofitting. We find that there is not one optimum insulation thickness, but many optima, depending on the individual boundary conditions and the chosen environmental indicator.
Conclusions
By incorporating a simplified LCA into the design process, the additional effort of performing LCA is minimized. The parametric approach allows the architect to focus on his main task of designing the building and finally makes LCA practically useful for design optimization. In the future, further performance analysis capabilities such as life cycle costing can also be integrated.
Implementing Building Performance Simulation (BPS) in a parametric design framework is a prevalent way of facilitating environmental assessments in early design stages. However, no up-to-date ...overviews of potential approaches are available, and no characterisation frameworks adapted for parametric BPS tools are present. In this study, such a framework was developed and its use demonstrated through an investigation of eleven available BPS tools for the parametric design framework Grasshopper®. It was found that the framework was able to successfully differentiate tools based on the level of BPS expertise integrated in the tools, and the allocation of responsibility for data entry and interpretation. A contrast was found between streamlined tools, and tools which provide more versatility. The characterisation framework, and the resulting overview of approaches, can be used to guide the future development of parametric environmental analysis frameworks for buildings.
Life Cycle Assessment (LCA) is considered as the most suitable way to assess the environmental impact of buildings. Due to its extensiveness and complexity, but also due to a lack of knowledge ...amongst architects, the LCA methodology is currently most often applied as a post-design evaluation and not used to support or optimize design decisions during early design stages. Therefore, this paper looks at possible solutions to apply LCA, including operational energy demand simulation, in early design from two different perspectives: design-oriented user requirements, derived from literature, a survey, interviews and a focus group with architects, and LCA simplification strategies based on a literature review. Both perspectives are discussed and merged into an evaluation framework that can be used to check the suitability of LCA-based environmental impact assessment (EIA) tools for use by architects during early design stages, but also to develop new design-supportive LCA-based EIA tools. In turn, this can contribute to an increased uptake of these tools in building practice.
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•The importance of building environmental impact assessment (EIA) is increasing.•Most influential design decisions are made by architects in early design.•Current life cycle based EIA tools are not adapted to the architects' needs.•Architect-oriented user requirements and LCA simplification strategies were derived.•The framework will improve the usability of EIA tools in architectural practice.
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