They classify the building in terms of their overall efficiency level and the renewable energy generation. The classes Plus and Premium were first introduced with PHPP version 9 (2015) as addition to the well-established Passive House Classic.

The functional definition of the Passive House and EnerPHit standards remain unchanged and is the same for all three classes (relating to useful energy demand for heating and cooling, as well as airtightness and comfort criteria). The assessment of the different classes is driven by the total primary energy demand, as well as renewable energy supply. The higher the achieved level of overall efficiency and of renewable energy generation, the higher the Passive House class. The Passive House classes are assessed using the PER methodology, Primary Energy Renewable.

The classification is available for newbuild Passive House buildings, as well as for EnerPHit retrofits. In the case of EnerPHit the PER targets are adjusted slightly to account for the higher heating energy demand limits

There are different ways of achieving a higher Passive House class. This article shows details and examples of how to reach the different Passive House Classes, including explanations of how different energy supply systems are considered in the PER methodology (biomass, solar thermal etc.).