The calculated certificate

Two categories, and the boundary between them is not always obvious. They are new build and substantial reconstruction.

A calculated certificate is prepared for buildings being designed, i.e. new, and for substantially reconstructed buildings. In both cases the certificate rests on calculation rather than measurement, because there is nothing yet to measure.

The definition of a substantially reconstructed building is decisive here, since it determines whether an ETA applies at all, and that definition must be checked against the regulation in force rather than estimated from the scale of the works. The definition must be checked in the regulation.

The validity period is shorter than most assume, and it starts somewhere other than expected. The date must be read off the certificate.

Question	Answer
Validity	2 years
Running from	the occupancy permit, not the date the certificate was prepared
What follows	a KEK certificate based on actual data

One useful consequence follows: time elapsed between design and the occupancy permit does not eat into the validity. When the two years end the building is not left without a certificate; it needs one based on actual data. The logic is clear: two years after a building is taken into use, actual consumption data exist, and a calculation is no longer needed.

Here is the practical core of the article, and it governs the whole project schedule. The validity of the certificate ties the procedural deadlines together.

According to professional sources, a new building will not be granted a building permit without an energy performance value meeting the requirements, and without one a renovated building cannot successfully apply for an occupancy permit. The certificate is therefore a precondition of the procedure.

The ETA is therefore not a document that can be added later but a condition that must be satisfied during the procedure. The practical consequence is unambiguous: the energy solution must be decided before applying for the building permit, not during construction.

Three observations, the first of which forestalls unnecessary worry. They concern validity and renewal.

The building does not become non-compliant when the ETA's validity ends. A valid certificate may nonetheless be needed for a sale or a letting, whose conditions must be checked, and the new certificate is then prepared on the basis of actual data.

The class may change in the process, which is one reason why calculated and actual certificates are not comparable. An owner expecting the same letter can be disappointed without anything having gone wrong.

Three steps in the right order, and the first cannot be made up for later. The first concerns massing and orientation.

#	Step	When
1	The energy solution is decided	in the early design phase
2	The ETA is calculated from the design	before applying for the building permit
3	Compliance is checked	at the occupancy permit, from which the 2 years run

The first step cannot be compensated for by later choices, as covered by the article on energy performance in design. Plant does not replace an architectural decision.

The calculated certificate is prepared for new and substantially reconstructed buildings and is valid for two years from the issue of the occupancy permit rather than from the date it was prepared. The ETA is a precondition of the permit procedure: without an energy performance value meeting the requirements a new building obtains no building permit and a renovated building's occupancy application does not succeed. When validity ends the building remains compliant, but any further certificate is prepared from actual data and the class may differ.

Four rules: treat the ETA as a precondition of the procedure, not as a later document. Count the validity from the occupancy permit, not from the certificate's date. Explain to the client that after two years a certificate based on actual data follows and the class may differ. Decide the energy solution before applying for the building permit.