The primary energy ratio is calculated by dividing the overall primary energy consumption per year by the gross internal floor area. The CO2 ratio and the water ratio are determined in an analogous way, whereas in the case of water the unit is converted from m3 to l [1]. An exception is made for swimming pools,
where the water ratio is expressed in l/users.
Afterwards, the building is arranged in the classification scheme, depending on the calculated ratios and the declared type of the building. Detailed information on the classification scheme is given in appendix 1.

Example C: Falk Comprehensive School
The total primary energy consumption adds up to 692.400 kWh/year. Dividing by the surface area of the building of 5.000 m2 results in a primary energy ratio of 138 kWh/m2/year. According to the classification scheme this primary energy ratio corresponds to class B. [2]

Dividing the CO2 emissions by the surface of the building makes a CO2 ratio of 30 kg/m2/year. That is why the school building is placed in class C for CO2 emissions. [3]

The water consumption of the building is 902 m3/year which corresponds to 902.000 l/year. From this follows that the water ratio is 180 l/m2/year) and that the buildings water consumption is class B. [4]