Circular Renovation Pathways - Evaluating Energy Performance, Thermal Comfort, Life Cycle Assessment and Material Flow Circularity in 1960s Swedish Residential Buildings

Sammanfattning

Many Swedish multifamily buildings from the 1960s are now reaching a stage where major renovation is needed to improve energy performance, indoor environmental quality, and long-term climate performance. At the same time, renovation strategies may involve trade-offs between operational energy savings, embodied carbon, thermal comfort, and material circularity. This thesis evaluates energy-efficient and circular renovation pathways for Swedish 1960s multifamily buildings, using the Äpplet and Päronet residential area in Växjö as a case study. The case is based on Vidingehem’s renovation project, which includes 220 apartments and was completed in 2025. Two representative building typologies were analysed: a low-rise building and a high-rise building. Three renovation scenarios with different levels of intervention were developed and assessed. The study combined dynamic energy simulation using Climate Studio/EnergyPlus, calibration against measured energy data before and after renovation, thermal comfort analysis, life-cycle assessment, and a material-level circularity assessment using OneClick LCA tools. The scenarios were evaluated in terms of total energy use, primary energy use according to BBR 29, indoor temperatures, overheating risk, global warming potential over a 50-year assessment period, carbon payback time, and circularity indicators. The results show that deeper renovation leads to substantial energy reductions in both representative buildings. Total energy use was reduced by approximately 8-10%, 43-44%, and 62-63% in Scenarios 01, 02, and 03, respectively. Winter indoor temperatures remained close to or above the housing company’s target, with an average improvement of approximately 0.5-1°C after renovation. However, the overheating assessment indicated increased risk in the high-rise building, especially on upper floors and in south-oriented apartments, while the low-rise building showed limited overheating risk. The LCA results indicate that deeper renovation reduces total GWP over the 50-year period, mainly due to reduced operational carbon. However, this is accompanied by increased embodied carbon and longer carbon payback times, particularly in Scenario 03. The circularity assessment showed similar patterns for both building typologies, with the highest circularity score in Scenario 02 and the lowest in Scenario 03. The study concludes that no renovation scenario performs best across all assessed indicators. Renovation strategies should therefore be evaluated using a multi-indicator approach, where operational energy savings are considered together with embodied carbon, thermal comfort, circularity, regulatory compliance, and long-term climate performance.