Heating degree day (HDD)

Figures describing the annual heating requirement in different localities have been calculated for indoor temperature of 17°C assuming that heating is stopped in spring when outdoor temperature rises above 10°C and started in autumn when it falls below 12°C. Figures for heating degree days are produced by the Finnish Meteorological Institute. These statistics have been compiled by using the heating degree day figure for Jyväskylä to describe the average heating requirement for the whole of Finland.