Long-term decarbonization prediction of buildings accounting for temporal variations in grid and material emission factors: A case study of timber-framed passive houses in the United Kingdom

Most studies have conducted life cycle assessment (LCA) in evaluating the carbon footprint of buildings to be independent of temporality in emissions accounting, which often overlooks the mitigation strategies to meet long-term emission reduction targets. This paper aims to investigate the whole-life carbon (WLC) emissions of a UK low-energy dwelling and examine how potential modeling approaches on low-carbon development will impact the LCA results. Particularly, the variations of future decarbonization of both grid and materials, as well as the photovoltaic (PV) allocation with and without batteries, are employed in the building's environmental performance analysis. The results demonstrated that considering the temporal perspectives can drastically reduce the WLC of buildings, representing up to 51 % compared to baseline calculations. With grid decarbonization, implementing a 4kWp grid-connected PV system can offset the building's operational emissions by 76 % compared to the existing 2kWp PV reference over a 60-year perspective. Our findings also revealed that adding batteries to grid-connected PV systems does not necessarily increase the emission savings achieved by system configuration for buildings when the decarbonization of both grid and materials is considered. Overall, this study highlights the importance of low-impact strategies that focus on upfront embodied carbon for policymaking in the building sector.