Simulation analysis of Finnish residential buildings’ resilience to hot summers under a changing climate

This study evaluated how residential buildings in Finland's cold climate withstand hot summers under climate change. The buildings' responses to outdoor temperatures, overheating, energy consumption, and cooling power demand were investigated with the actual data of the hot summer of 2018, and its projected conditions for 2050 and 2080 under the highest Representative Concentration Pathway. The results revealed that lightweight structured detached houses reacted about two times faster to outdoor temperatures. The new apartment and the new elderly house, constructed according to the latest Finnish building code, showed slower responses and lower indoor temperatures during current and future hot summers with no degree hours above the Finnish health limits of 30 °C/32 °C. Conversely, the old non-renovated apartment building and elderly house built in the 1970s–80s experienced higher indoor temperatures. Their indoor temperature surpassed 30 °C/32 °C even in the current climate. Although passive solutions reduced indoor temperatures effectively, hot summers necessitated active cooling systems. The cooling energy and power demand in the old buildings were higher compared to the new ones. However, the cooling electricity consumption was considerably small compared to the heating and total energy consumption in all the studied buildings. It was projected to increase in future climates by 40–160 % depending on the building type and climate scenario.