Embodied impacts of residential stocks; multi-level assessment of materials, buildings, typologies and functional units to support policymaking towards sustainable housing

Purpose This study addresses the lack of integration between component-, building- and urban-scale life cycle assessments (LCAs) in the built environment, which limits their effectiveness in guiding policymaking for prospective impact reductions. It proposes a multi-level approach for assessing the embodied impacts of residential building stocks to support more comprehensive and informed decisions. Design/methodology/approach A representative stock of sixteen newly constructed residential buildings in New Zealand, spanning four typologies—apartments, townhouses, double-storey detached and single-storey detached (SD) dwellings—is assessed using multi-level LCA (according to ISO 14040:44) across four environmental impact categories: global warming, eutrophication, ozone depletion and acidification. Two functional units, gross floor area (GFA) and number of occupants, were used to analyse and compare results. Findings Timber and steel emerged as the most impact-intensive materials across most categories due to their extensive use, while plastics and paint contributed between 10 and 29% of impacts. Apartments and townhouses showed higher impacts per GFA due to structural requirements—up to 139 and 20% greater than SD houses, respectively. Upfront impacts (modules A1–A5) accounted for 63%–75% of total impacts. Functional unit selection revealed significant variations, with the impact percentage differences for some buildings shifting from +59% to −25%. Originality/value The novel proposed approach enables the identification of impact hotspots often missed by fragmented assessments. By integrating scales and functional units, it offers a necessary understanding of residential embodied impacts—crucial for designing future housing and currently absent from global literature.