1. What the energy performance value measures
The definition in the regulation in force is precise, and each part of it carries a consequence. The definition should be read literally.
| Element | Content |
|---|---|
| What it reflects | the building's complex energy use: indoor climate, domestic hot water, household and other electrical appliances |
| Under what use | the building's typical use, not that of a particular household |
| Unit | kWh per square metre of building area per year |
The word "typical" is decisive. The divergence from actual costs follows from it, as covered by the article on why calculation and reality diverge, and it is a feature of the definition rather than an error in the calculation.
2. Per which area
The denominator matters as much here as it does with construction cost, and it is underestimated. The wrong area gives the wrong class.
The energy performance value is calculated per square metre of room-temperature area, and space kept at a low temperature setting is not counted as room-temperature area. Ancillary rooms kept at a low temperature therefore do not increase the denominator, although they are part of the building.
The practical consequence is direct: the definition of area affects the result, and it must not be confused with the area recorded in the building register. The terms are defined in the regulation, and the designer must use the regulation's concept rather than the everyday one.
3. Why this guide does not state limit values
A deliberate choice whose reason is a risk assessment rather than caution. Limit values are not reproduced here.
| Reason | Explanation |
|---|---|
| The values changed on 01.06.2025 | together with the new class scale |
| The values depend on intended use and, for houses, on area | one figure does not fit all |
| A wrong value is directly harmful | obtaining the building permit depends on it |
The applicable limit value must be taken from the annex to the regulation in force, not from a summary, and this holds even where a similar case was resolved recently. Summaries age quickly.
4. The three required levels
The logic of the levels is more stable than the figures, which is why it is worth memorising instead of them. The figures must be checked each time.
| Level | For whom |
|---|---|
| Nearly zero-energy building | the highest level, required of new buildings |
| Low-energy building | applies in certain exempted cases |
| Reconstruction level | a separate and lower requirement for substantially reconstructed buildings |
The hierarchy is stable although the figures attached to it have changed. It is therefore more useful to know which level applies than to try to memorise values.
5. What the cost-optimal level is
One concept explains where the figures come from at all, and it also tempers any expectation that they will stay put. It is the cost-optimal calculation.
Cost-optimal energy performance is, within the meaning of the regulation, the limit value for the energy performance value at which the minimum total financial cost over the building's life cycle is achieved. Updating the limit values rests on cost-optimal level calculations, and according to information published by the Ministry of Climate the last such analysis was carried out in 2022.
The figures are therefore calculated rather than political, which explains why they are updated periodically. Change follows the calculation rather than a decision.
Summary and four practical rules
The energy performance value reflects the building's complex energy use at typical use, expressed in kilowatt-hours per square metre per year, and it is calculated per square metre of room-temperature area, from which space kept at a low temperature setting is excluded. There are three required levels: nearly zero-energy for new buildings, low-energy in certain exempted cases, and a separate lower level for substantially reconstructed buildings. The limit values derive from cost-optimal level calculations, the last analysis having been made in 2022.
Four rules: use the regulation's concept of area, not the register's. Take the limit value from the annex to the regulation in force for every project afresh. Memorise the hierarchy of levels rather than the figures. Explain to the client that the figure describes typical use, not theirs.
This article offers professional orientation as at the date of verification. It replaces neither the regulations in force nor the assessment of a competent specialist.