Impacts of Energy Efficient Constant Output Heating on the Moisture Conditions of Unoccupied Summer Cottages in Finland

Finland has around half a million summer cottages. An increasing demand exist for using these cottages also in other seasons. The influence of constant output heating is studied for energy saving purposes while avoiding moisture damage in the cottages. The proposed type of heating requires only a fraction of amount of electrical energy in comparison with conventional heating. Field measurements, which are presented in current paper, aim at indicating the actual moisture conditions in unoccupied Finnish summer cottages. Field measurements in seven non-insulated massive log walled cottages in Tampere region (Finland) have been performed during 2007–2009. Based on the values of indoor and outdoor RH (at one-hour interval) the monthly average differences between indoor and outdoor water vapour content were determined. Prevailing conditions of moisture deficit were found in summer cottage case buildings during the measurement period. These results oppose to the usual conditions of moisture excess in Finnish residential buildings. Despite the difference in moisture conditions the envelope structures in summer cottages and in residential buildings are often similar.Peer reviewe