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

Abstract

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.