Energieausweis (energy performance certificate) and Heizwärmebedarf (heating energy requirement - HWB)

The Heizwärmebedarf (heating energy requirement) in the Energieausweis (energy performance certificate) shows how much heat your house theoretically needs. It is a good initial indication of whether a heat pump is suitable.

The Energieausweis (energy performance certificate) describes the energy performance of a building. You need it, among other things, when selling or renting out. The most important key figure for the heating system is the Heizwärmebedarf (heating energy requirement - HWB). It indicates the theoretical amount of heat that must be supplied to the rooms for heating, relative to the gross floor area. It is shown for the climate at the location and for a reference location for the whole of Austria. The scale ranges from class A++ to G, with G being the worst value.

What the HWB means for the heat pump

The less heat your house needs, the lower the flow temperature can be and the more efficiently a heat pump operates. klimaaktiv classifies heating systems in a heating matrix according to the HWB at the location (HWB SK). The class limits there are: under 10 kWh/m² per year (A++), up to 15 (A+), up to 25 (A), up to 50 (B), up to 100 (C), under 150 (D), and above that E to G.

Important to know

The HWB is a calculated value, not a measured consumption. How warm you heat your home and how you ventilate it also play a role. It is not sufficient for designing the heat pump. This requires a standardised heating load calculation.

If you do not have an Energieausweis (energy performance certificate) yet, klimaaktiv recommends having one prepared and using an energy advisory service in your federal state. You can estimate whether your house is generally suitable using the suitability check.

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