Principles to select new test reference year assessing the annual energy for heating and cooling of buildings in Finland

The indoor climate and energy calculation and simulation results depend heavily on the input parameters, of which one is boundary condition. The energy performance of buildings should be calculated on the basis of a standardized methodology, with the same outdoor climate. In this study, the long term climate data have been analysed and principles to select the new test reference year assessing the annual energy for heating and cooling of buildings have been worked out. The new test reference year is based on modified SFS-EN ISO 15927-4 method. The primary selection of is made on the basis of dry-bulb temperature and global solar radiation. The water vapour pressure and wind speed is used for secondary selection. Based on heating and cooling energy consumption of example buildings weighting factors are calculated for climate parameters. To guarantee the maximum frequency and sequence of the test reference year, it contains months from a number of different years. With this modified method the new test reference year assessing the annual energy for heating and cooling has been worked out for Finnish buildings. The method is possible to adapt also for other countries in cold climate.