This standard gives a simplified calculation method for assessment of the annual energy use for space heating of a residential or a non-residential building, or a part of it, which will be referred to as "the building".
It does not apply to buildings with air conditioning systems likely to provide space cooling during the heating season.
This method includes the calculation of:
1. the heat losses of the building when heated to constant internal temperature;
2. the annual heat required to maintain the specified set-point temperatures in the building;
3. the annual energy required by the heating system of the building for space heating, using heating system characteristics which are to be found in specific European or International Standards, or, by default, in national documents.
The building can have several zones with different set-point temperatures, and can have intermittent heating.
The calculation period is the month. For residential buildings the calculation can also be performed for the heating season. Monthly calculation gives correct results on an annual basis, but the results for individual months close to the beginning and the end of the heating season can have large relative errors. Annex J provides some information on the accuracy of the method.