Indoor climate conditions and hygrothermal loads in historic wooden apartment buildings in cold climates.

To design and assess indoor climate, thermal comfort, and the hygrothermal performance of a historic building it is essential to obtain data on the indoor temperature and humidity conditions. This paper analyses indoor climate conditions in historic wooden apartment buildings in Estonia and presents an applicable hygrothermal load model for designers. The average indoor temperature of 41 apartments in historic wooden apartment buildings was 21.0 °C in winter and 24.5 °C in summer. Using the indoor climate category III of the standard EN 15251, it was found that the temperature was outside the target values in 83% of the apartments in winter and in 25% in summer. Throughout the year, the indoor temperature was below the target values during 20% of the time while in winter it was above the target values during 4% of the time. Variations in indoor temperature reflect occupants' main complaints about unstable temperature and cold floors during the winter period. The daily average moisture excess was 3.3 g/m³ during the cold period and 0.6 g/m³ during the warm period at the average air change rate of 0.56 h-1 and 0.79 h-1, respectively. Moisture generation indoors was 60 g/h at the average living density of 26 m² /person in the historic wooden apartment buildings. For stochastic analyses in historic wooden buildings, we developed an indoor hygrothermal load model that is in good agreement with measured results. [ABSTRACT FROM AUTHOR]