Summer Thermal Comfort in New and Old Apartment Buildings

In Nordic countries overheating and cooling systems have not been the issue in apartment buildings. Historically and even in the beginning of 2000 there were not indicated such problems. New architecture with larger windows and strict energy performance requirements has changed the situation. If adequate measures are not used, new buildings may be easily overheated. In the design this is a question of temperature simulations, and application of mostly passive design measures which might be needed to be supported with installation of active cooling system in some cases to fulfil minimum requirements for energy performance and thermal comfort. Even revised EPBD increase the role of overheating problems and suggest using passive cooling technologies like shadings. This study conducted field measurements in more than 100 Estonian apartments. Results show that the overheating occurs in modern buildings where average room temperature was about 1°C higher than in old buildings. According to criterion of weighted excess degree hours over +27 ºC, there was no overheating in old apartment buildings, but in new apartment buildings the criterion was exceeded in 13.7% of apartments in 5 week period. The paper reports field measurements and analyse ventilation, orientation etc. effect on overheating.