Potential Impacts of Replacements in Building-Level Life Cycle Assessment: A Residential New-Build Case Study

The reduction in embodied environmental impacts in residential construction is increasingly important as operational energy performance improves and the relative contribution of materials, replacements, and end-of-life processes grows. This study presents a building-level life cycle assessment of a block of flats in Czechia over a 50-year reference study period. The inventory was derived from the bill of quantities and technical documentation and modelled in LCA for Experts using the integrated Sphera database. The assessed modules comprise A1–A3, A4, B4, B6, C1–C4, and D. Operational energy use in B6 was the largest positive contributor to global warming potential, reaching 16.31 million kg CO2 eq. (1111 kg CO2 eq./m2). Product-stage impacts in A1–A3 amounted to 7.15 million kg CO2 eq. (488 kg CO2 eq./m2), while replacements in B4 generated 3.32 million kg CO2 eq. (227 kg CO2 eq./m2), equivalent to approximately 46% of initial product-stage impacts. Replacement hotspots occurred mainly in non-load-bearing elements, equipment and facilities, façade and roof components, and technical systems. Including B4 changes hotspot prioritisation: products with limited A1–A3 impacts may become significant because of shorter service lives and repeated replacement. Linking building parts, material categories, and individual datasets supports durability, maintainability, and replacement planning in life-cycle GWP reduction.