The risk of overheating and energy demand of new and old Finnish apartment buildings in the cooling season

This study has compared the risk of overheating of a new and old apartment building in Finland and aimed to improve the indoor temperature conditions of the new apartment building using the passive strategies (sun shading, window opening, and window properties) and an active cooling system. So that seven different cases were defined and simulated. Regarding the results, the risk of overheating in the old building is significantly less than in the new building, and using new well-insulated windows with the same old wall construction in the old building, decreases the heating demand but has no significant effect on indoor air temperature. So that the windows are more important for energy usage but not for the indoor air temperature in the old Finnish apartment building during the summer period. Using openable windows would be the best passive solution for keeping the indoor air temperature of the spaces of the new building within the comfort limits with less than 10% of the time above the recommended temperature limits based on EN 16789-1 standard without any significant increase in heating demand. While Using an active cooling system in the living room of each apartment is the only solution that can provide thermal comfort for 100% of the cooling season in all the spaces including bedrooms.