Carbon and cost implications of adaptive reuse

As cities set more ambitious climate goals, decisions about the built environment carry increasing weight. A key question is whether to demolish aging buildings or refurbish them. While cost often takes priority, research increasingly points to the overlooked environmental toll of replacement. The reviewed literature suggest that refurbishment and adaptive reuse (AR) are generally more environmentally sustainable than new construction (NC). Case studies analysing both environmental and economic impacts indicate that building refurbishment can outperform NC in both respects, though outcomes vary widely depending on context. However, not many studies have yet combined life cycle assessment (LCA) and life cycle costing (LCC) specifically for AR. In the Helsinki metropolitan area of Finland, rising housing demand combined with a growing stock of unused office buildings is accelerating urban transformation. As commercial and office buildings are demolished at an average age of just 36 years, there is significant potential to convert underutilized offices into housing. This article presents a case study examining the AR of an office building into residential use, focusing on greenhouse gas (GHG) emissions assessed through LCA and cost-effectiveness evaluated through LCC. The study shows that, compared to the NC baseline (100%), AR results in 54% of upfront GHG emissions and 81% over a 50-year life cycle, while accounting for 48% of initial building costs and 62% of total life-cycle costs. Repurposing existing office buildings into residential blocks can contribute to meeting housing demand, support climate goals, and potentially reduce costs compared with demolition and new construction.