Field survey of overheating problems in Estonian apartment buildings

Abstract

In Nordic countries overheating problems have not constituted a recognized problem to date. However, modern buildings, typically with larger windows, have changed this situation. New regulations based on Energy Performance of Buildings Directive (EPBD) directive require that overheating problems are controlled and recommend the use of passive cooling measures. EPBD sets that temperature simulations or other verifications are to be used at the design stage. If necessary, passive measures may be supported with active cooling systems to meet the requirements for summer thermal comfort. During this study field measurements were conducted in more than 100 Estonian apartments by recording indoor temperatures from a 3-month period; an overheating assessment and the impact of ventilation, orientation and window size on recorded overheating were studied. Our results show that overheating occurs in the modern buildings where the average room temperature was continuously about 1K higher than in the old buildings. According to the criterion of weighted excess degree hours over+27°C used in Estonian regulation to prevent overheating, no overheating occurred in old apartment buildings, but the criterion was exceeded in 13.7% of the apartments in new apartment buildings. The results showed that, without adequate passive temperature damping measures used, modern buildings were regularly overheated.