As the final energy consumption of a building depends on climatic conditions and since these climatic conditions vary at one particular geographic location over the years, the consumption data have to be corrected. This correction concerns the energy consumption for space heating. To apply the correction the amount of final energy consumption for space heating is multiplied with the weather correction factor. It is usually provided by energy utilities or meteorological offices.

The weather correction factor does not take into account climatic differences between two different climatic zones. That is why the classification result of a school building situated in Portugal cannot be compared with the classification result of a school building situated in Finland.