End-of-life modelling of buildings to support more informed decisions towards achieving circular economy targets

Abstract

Purpose Life cycle assessment (LCA) is an internationally accepted method to assess the environmental impacts of buildings. A major methodological challenge remains the modelling of the end-of-life stage of buildings and allocation of benefits and burdens between systems. Various approaches are hence applied in practice to date. This paper compares the two methods widely renowned in Europe—the EC product environmental footprint (PEF) method and the CEN standards: EN 15804+A1 and EN15978—and offers insights about their fitness for achieving circularity goals. Methods The EC PEF method and the CEN EN 15804/EN 15978 standards were methodologically analysed with a focus on the end-of-life modelling and allocation approach and were applied to a building case study. The EN 15804+A1 standard explains the guidelines but does not offer a modelling formula. Accordingly, this paper proposes a formula for the CEN standards using identical parameters as in the end-of-life circular footprint formula (CFF) of the EC PEF Guidance v6.3 to increase consistency among LCA studies. The calculation formulas were then applied to a newly constructed office building. A comparative analysis of both the implementation and results are described, and recommendations are formulated. Results In the absence of databases compatible with the two LCA methods and comprising all building products, the Ecoinvent datasets had to be remodelled to enable a comparative modular assessment. This proved to be a laborious process. The EC PEF method and CEN standards showed similar impacts and hotspots for the case study building. The module D in the CEN standards includes a significant share of positive impacts, but due to collective accounting, it does not clearly communicate these benefits. The summation of burdens and benefits in the EC PEF method reduces its transparency, while the allocation and quality factors enable this method to better capture the market realities and drive circular economy goals. Conclusions The construction sector and the LCI database developers are encouraged to create the missing LCA databases compatible with the modular and end-of-life allocation modelling requirements of both methods. More prescriptive and meticulous guidelines, with further harmonization between the EC PEF method and the CEN standards and their end-of-life allocation formula, would largely increase comparability and reliability of LCA studies and communications. To improve transparency, it is recommended to report the module D impacts per life cycle stage as per the CEN standards and the burdens and benefits separately for each life cycle stage as per the EC PEF method.

An Evaluation of the Impact of Databases on End-of-Life Embodied Carbon Estimation

“…Contrarily, this study has shown that limited databases can significantly impact the EC calculation outcome [45]. This lack of data can be attributed to the comparatively long building useful lifespan and uncertain nature of the EoL processes or activities [46]. Although the use of default national EoL values and assumptions enable EoL modelling and reduce the time required in performing LCA, the lack of data sources providing ECFs hampers the reliability of assessment results.…”

“…In their study to model the end-of-life phase of buildings and allocate benefits and burdens, Mirzaie et al [46] found that information in generic databases concerning EoL activities such as deconstruction, transportation, recycling, and disposal, in many cases, is little or non-existent. Considering that concrete forms the larger proportion of this supermarket building, recycling concrete can further reduce the life cycle carbon emissions [30].…”

Design for Recycling Strategies Based on the Life Cycle Assessment and End of Life Options of Plastics in a Circular Economy

“…also used CFF as one of the EoL modeling approaches for buildings, to achieve circular economy targets. [ 83 ]…”

“…[82] Mirzaie et al also used CFF as one of the EoL modeling approaches for buildings, to achieve circular economy targets. [83] Accorsi et al [36] Huang et al [84] Impact factors of sustainable design and development of plastic molds Almeida et al [85] Material selection for beverage packaging Foschi et al [86] Integrated decision-making process in packaging redesign Alpizar et al [87] Policy instruments for decision-making to curb marine litter Sherwood et al [88] Recirculation and sustainable product design for bio-based products Vogt et al [89] Redesign polymers and key challenges for advancement of plastic recycling Leal et al [90] Indicator based product design approach to improve circular economy Antonopoulos et al [91] Factors affecting the recycling of post-consumer plastic packaging waste Löw et al [92] Guidelines and implementation of DfR in plastics Mendes da Luz et al [93] Methodology to integrate LCA in the product development process…”

Multi-Criteria Decision Analysis Using Life Cycle Assessment and Life Cycle Costing in Circular Building Design: A Case Study for Wall Partitioning Systems in the Circular Retrofit Lab

“…Module D [13]) and the Product Environmental Footprint (PEF) method [14] applies a generic system expansion approach for all industrial sectors including the construction sector, that does not allow for modeling multiple life cycles (e.g., PEF [14]). There are issues with deciding on end-of-life calculations, end-of-waste of various materials [15] and available life cycle assessment tools do not have a straightforward way for extending lifetime of buildings and building elements e.g., Belgian TOTEM, a life cycle assessment tool used to facilitate LCA in architectural practice [16]. A common representation of impacts in LCA is the bar graphs that represent total impacts per impact category per functional unit.…”