Benefits and challenges of visualising embodied and whole life carbon of buildings

Embodied and whole life carbon of buildings are increasingly gaining attention. However, embodied carbon calculation is still far from being common practice for sustainability assessment of buildings. Some of its greatest difficulties lie with the long life lifespan of buildings which implies a great unpredictability of future scenarios and high uncertainty of data. To help understand which life cycle stages should get the most attention when considering a building project, this paper proposes a new visualisation method based on Sankey diagrams for whole life carbon that allows one to cluster the carbon emitted in each of the life cycle stages as identified in current BS 15978 standards. With the proposed method, the carbon figures can be further broken down to account for building assemblies and components. Additionally, the method is equally suitable to account for physical quantities of what is embedded in buildings and their components. As such it can supplement some units of existing assessment methods (e.g. metal depletion measured in mass units of Feeq) and turn it into mass units of embodied steel. With such new metric, a life cycle assessment would include knowledge on flows as well as quantities. Such information could then be linked to the building permanently and smartly to be updated when necessary as the building evolves, changes, and gets upgraded, building on the theoretical foundations of the shearing layers of buildings. As such, this information could be embedded within BIM which is fully suitable to store parametric details for each building component

Inclusion of on-site renewables in design-stage building life cycle assessments

This paper investigates the inclusion of renewables in building life cycle assessments. On-site renewable electricity generation is increasingly common in the built environment, but existing guidance for the inclusion of these renewable systems in design-stage life cycle assessment is limited. The life cycle assessment of a building with 42.8 kWpeak solar photovoltaic array is used as a case study to investigate the effect of different assumptions on the assessment outcome. The case study results are then used to suggest good practice. The paper also highlights where further research is required to provide reliable design-stage assessments in future

Reducing Embodied Carbon in the Built Environment: A Research Agenda

In spite of significant global efforts, the International Energy Agency suggests that buildings-related emissions are on track to double by 2050. Whilst operational energy efficiency continues to receive significant attention by researchers, a less well-researched area is the assessment of embodied carbon in the built environment in order to understand where the greatest opportunities for its mitigation and reduction lie. This paper reports on available mitigation strategies to tackle embodied carbon identified through a systematic review of the available academic evidence. It also investigates the scope and scale of current academic investigations to highlight where significant gaps are for impactful further research on the topic. In total, 17 mitigation strategies have been identified from within the existing literature which have been discussed individually. Results reveal that a one-size-fits-all approach is unlikely to yield beneficial results and future research should be diverse in breadth and scope, locally accurate, and significantly interdisciplinary

Decision-making for the demolition or adaptation of buildings

This paper considers why the decision may be made either to demolish or adapt existing buildings on brownfield sites and compares real-life decisions to those produced by theoretical design-support tools. Five case studies, including three individual buildings and two master plan sites of multiple buildings, were investigated through interviews with stakeholders. Reasons for retention included heritage value, architectural quality and government incentives, while reasons for demolition included maximising land value, lack of architectural significance and poor building condition. The analysis showed that the theoretical tools were useful for their intended purpose of analysing a portfolio of assets but that they could be improved by providing higher weightings for heritage values and extending the tools to assess different end uses and forms of adaptation. By testing the tools on master plan sites, the paper also identifies urban design variables, such as land efficiency, which would need to be incorporated for this purpose.The authors gratefully acknowledge the Engineering and Physical Sciences Research Council (EPSRC) for funding this research through the EPSRC Centre for Doctoral Training in Future Infrastructure and Built Environment (EPSRC grant reference number EP/L016095/1)

Developing a generic System Dynamics model for building stock transformation towards energy efficiency and low-carbon development

A Promoting the decarbonisation of buildings requires effective policy measures. An integral part of policy design is ex-ante evaluation of possible policy options and effects. System Dynamics, one of a range of potential modelling paradigms, emphasises

Design strategies for low embodied energy and greenhouse gases in buildings: analyses of the IEA Annex 57 case studies

This paper introduces the IEA Annex 57 case study method, consisting of a format for describing individual case studies and an evaluation matrix covering all case studies. Sample case studies are used to illustrate the method and the evaluation matrix through a first preliminary analysis. In compiling and evaluation existing, transparent case studies we have taken a stakeholder perspective. By so doing it is intended to identify fordecision makers the key issues affecting EE/EC in buildings. Analysis in this paper focuses on one of the six case study themes, building design strategies for EE/EC mitigation and references cases covering e.g. material selection, building shape, construction stage strategies and strategies to handle the trade-off between embodied and operational impacts in net-zero emission building design

The Reporting of End of Life and Module D Data and Scenarios in EPD for Building level Life Cycle Assessment

This paper identifies the need for Environmental Product Declarations (EPD) to provide End of Life (EoL) and Module D data for products for use in building level Life Cycle Assessment (LCA). Although the provision of data for EN 15804 Modules A4-D is not currently mandatory for EPD, many currently report some or all of these. This paper provides an overview of the existing reporting of the end of life (Modules C1-4) and Module D and the types of scenarios used in European EPD. Using examples from existing EPD for two product groups, this paper examines the variation in approaches to scenarios for Module C and D. It explores the difficulties brought by this variation and discusses benefits from using default national scenarios at end of life, but additionally considers the advantages of providing alternative EoL scenarios for products to promote the circular economy

Estimating Lifetimes and Stock Turnover Dynamics of Urban Residential Buildings in China

Building lifetime and stock turnover are both key determinants in modelling building energy and carbon. However in China, aside from anecdotal claims that urban residential buildings are generally short-lived, there are no recent official statistics, and empirical data are extremely limited. We present a system dynamics model where survival analysis is used to characterise the dynamic interplay between new construction, aging, and demolition of residential buildings in urban China. The uncertainties associated with building lifetime were represented using a Weibull distribution, whose shape and scale parameters were calibrated based on official statistics on floor area up to 2006. The calibrated Weibull lifetime distribution allowed us to estimate the dynamic stock turnover of Chinese urban residential buildings for 2007 to 2017. We find that the average lifetime of urban residential buildings was around 34 years, and the overall residential stock size reached 23.7 billion m2 in 2017. The resultant age-specific sub-stocks provide a baseline for the overall stock, which—along with the calibrated Weibull lifetime distribution—can be used in further modelling and for analysis of policies to reduce the whole-life embodied and operational energy and CO2 emissions in Chinese residential buildings

Forecasting Urban Residential Stock Turnover Dynamics using System Dynamics and Bayesian Model Averaging

Knowing the size of the building stock is perhaps the most basic determinant in assessing energy use in buildings. However, official statistics on urban residential stock for many countries are piecemeal at best. Previous studies estimating stock size an

The Role of Stakeholders in Masterplan Regeneration Decisions

Brownfield sites often contain existing buildings and during regeneration the decision to demolish or adapt them should consider sustainability principles. This paper discusses decision-making criteria obtained through a literature review and primary research including 18 interviews, 2 workshops and 2 focus group discussions. The most frequently mentioned criteria including building condition; heritage value and capital costs are evaluated. Criteria are then analysed from different stakeholder perspectives and the paper identifies where stakeholder values align. The paper forms part of a three year research project which aims to develop a decision-making framework to assist with integrated and holistic decision making