CPE for an apartment: what data the methodology requires and what a calculation on a block apartment looks like

The owner of an apartment who sells or rents it usually asks three things: whether a certificate is needed, what to give the auditor, and why the certificate of the building is not enough. For the auditor, the answer to the second question is the one that decides how long the work takes. This guide starts from the text of Law no. 372/2005 and from the apartment certificate model in Mc 001-2022, not from lists of documents that circulate informally.

When is a CPE needed for an apartment?

Law 372/2005 defines in art. 3 pt. 11 the "building unit" as a zone or part of a building, a floor or an apartment, designed or modified to be used separately. Art. 21 para. (1) lit. a) requires a certificate for the building categories in art. 7 para. (1), among which "residential – collective or individual", and for their units, when they are built, sold, rented or subject to major renovations. For the categories listed in art. 8, the certificate is optional (on written and justified request, together with an energy audit report), and for those in art. 8 para. (2) it is not drawn up (art. 21 para. (4)).

The owner's obligations do not end with the drawing up. Art. 22 para. (1) requires that, before the contract is concluded, a copy of the certificate be made available to the potential buyer or tenant. On sale, the original is handed to the new owner (para. (2)), and on registration of the sale-purchase or lease contract a copy is filed with the tax authority (para. (3)). Sale-purchase contracts concluded without observing para. (1) are subject to relative nullity. Art. 24 further requires that sale or rental advertisements state the performance indicators from the certificate.

The certificate is drawn up by an energy auditor for buildings, at the request of the investor, owner or administrator, and is valid for 10 years from the issue date, except where major renovation works are carried out that change consumption (art. 21 para. (2)). Certificates without a unique registration code issued by the competent ministry are null by law (art. 21 para. (8)). Exceptions are the preliminary certificates, drawn up before acceptance as a simulation, which are provisional (art. 21 para. (4¹)), and the case of buildings sold before acceptance, where the buyer is offered a certificate without a unique code (art. 23 para. (3)).

Does the apartment have its own certificate, not only that of the building?

Yes. Besides art. 21 para. (1) lit. a), which includes the units of the building, art. 21 para. (3) says that the certificates for building units in collective residential buildings are drawn up on the basis of the methodology, and Mc 001-2022, at pt. 5.1, provides that the certificate is completed according to the evaluated object: figure 5.1 for a building or building unit, figure 5.2 for an apartment. The apartment model has its own section "Date privind apartamentul certificat" (Data on the certified apartment).

The methodology specifies two further things that change the auditor's work. First: for apartments, the notion of reference building loses its meaning, so the reference building obtained for a whole building is not calculated. Second: the energy classes of an apartment are taken from table 5.7 if the apartment is in a house and from table 5.8 if it is in a block (note 2 to the energy classification in chapter 5).

What data do the certificate model and the technical annex require, specifically?

Mc 001-2022 does not list the documents that the owner must hand to the auditor. What it lists is the content of the certificate (figure 5.2) and of the technical annex for the apartment (pt. 5.1.4), and the auditor needs the data that feed these fields. The list that follows is therefore deduced from the official model, not from a legal document requirement:

• Identification of the apartment (page 1 of the certificate): the building category, the year of construction or of major renovation, the address, the GPS coordinates, the height regime, the purpose of the elaboration (sale, rental, acceptance, information).
• Geometry: the reference floor area, the habitable area (on page 1) and the reference interior volume of the apartment (on page 1 and in the technical annex).
• Building and location (technical annex): the building type, the climate zone, the wind zone, the structural system.
• Envelope of the apartment: for each element (exterior walls, windows, floors, stairwell walls, etc.), the calculated corrected thermal resistance, the normative one and the area. The auditor obtains them from surveys, plans and measurements.
• Installations: for heating, domestic hot water, cooling, mechanical ventilation and lighting, the annex requires stating whether the installation exists in the apartment, whether it is functional and what type of system it is. If the installation is missing, the annex provides a virtual system, for example an electric heating system at thermal comfort parameters.
• The maximum number of persons, real or normative, entered in the annex. For domestic hot water, pt. 3.3.6.2 establishes the demand from the habitable area and the number of equivalent consumers, so the habitable area counts directly in the calculation.

The same type of information underlies the estimation of air permeability. For existing buildings, Mc 001-2022 estimates the number of air changes at 4 Pa as a function of the building category (single-family or multi-apartment), the exposure class, the shelter class and the state of degradation of the joinery. Photographs of the windows and the state of the gaskets therefore count directly in the result.

Example: a 1975 block apartment, Constanța

The demonstration M1 in Zephren is a 65 m² apartment in a large-panel block from 1975, in Constanța (placed in the demonstration in climate zone I), without envelope insulation, connected to district heating, with an electric boiler for hot water. The calculation, made according to Mc 001-2022, gives a total primary energy of the order of 610 kWh/m²·year and energy class G. For an apartment in a block, classification is made with the scale of table 5.8.

The example shows why the field data matter: the same area of 65 m² can end up in different classes depending on the thermal resistance of the exterior wall, the state of the joinery and the type of hot water system. In M1, both the exterior wall and the glazing exceed the maximum admissible transmittance, and the technical annex shows them in the fields of calculated corrected and normative resistances. The recommendations for increasing performance are then those in Annex 1 to the CPE.

Points to watch

• The building's data are reused for an apartment without taking into account its position (intermediate floor, top floor, corner), which changes the envelope areas.
• The class table for a house is applied to a block apartment. For a block, table 5.8 is used.
• The purpose of the elaboration is omitted or the one declared does not match the situation, for example a certificate prepared for sale but ticked as information.
• The certificate is handed over without a unique registration code. It is null by law (art. 21 para. (8)).
• The usable area is entered in the habitable area field, without saying so in the assumptions of the calculation.

How a calculation program helps

The fields above are entered once, and the program calculates primary energy, class and emissions and completes the certificate model and the annexes. Zephren has no official validation from MDLPA and does not replace the field survey or the responsibility of the certified auditor. You can go through the same workflow on the data of an apartment of your own in the Zephren calculation program, with the free trial.

*Verified on 20 October 2026, against the text of Law no. 372/2005 (republished, as amended by Law no. 238/2024, MO no. 714/22.07.2024) and the official edition of Mc 001-2022 (MO no. 46 bis/17.I.2023). Courtesy translation; the Romanian version prevails. This is not legal advice.*