The overlooked impact of materials’ reference service life on the whole-building life cycle assessment results
Abstract
Life cycle assessment (LCA) offers a robust framework for evaluating the environmental impacts of a building throughout its entire life cycle, from material extraction to end-of-life. A key source of uncertainty in LCA is the reference service life (RSL) of building materials, particularly non-structural components, which are often overlooked compared to structural elements. This study aims to examine how the RSL of non-structural materials influences the LCA results of different building types. This study addresses this objective by developing a RSL database for non-structural building materials, based on North American Environmental Product Declarations (EPDs). It prioritizes components that exhibit high variability and explicitly considers their RSL in LCA calculations, which are frequently ignored or replaced with default values in detailed LCA modeling. The database was applied to three representative residential building architypes, single-family (SF), row house (RH), and multi-unit residential building (MURB), assuming a 75-year lifespan as the baseline and varying it between 60 and 90 years. Material quantities for the SF and RH models were obtained from detailed BIM models, while the MURB model used standard quantities from a bill of materials (BOM). The results reveal that underestimating the RSL of a single high-impact component can significantly alter embodied greenhouse gas (GHG) emissions in the B4 module. For example, assuming the highest replacement rates for the non–structural materials increase total LCA results by 35–37% for SF and RH buildings, and by approximately 19% for MURB. Moreover, extending building lifespan from 60 to 90 years can further change wbLCA results increased by about 47% and 58% for SF and RH, and 23% for MURB. These findings highlight the critical need for accurate and standardized RSL data. It is recommended that policymakers require the inclusion of verified RSLs in EPDs, supported by product-specific testing or modeling. Additionally, the development of region-specific, open-access RSL databases would help reduce uncertainty, improve comparability, and ultimately enable more accurate assessments and reliable life cycle-based decision-making.