nZEB in 2026: what Mc 001-2022 actually requires for new buildings

For a certified energy auditor, nZEB has for several years no longer been a conceptual novelty, but a compliance requirement checked for every new building entering the portfolio. There is still a point where interpretations differ — especially for those who have not recently reread the text of the law and of the methodology. This article goes through what the Romanian legal framework actually says, without approximate wording.

What nZEB means under the Romanian legal framework

The term "nZEB" (nearly Zero-Energy Building) has a precise legal definition in Romania, given by Law no. 372/2005 on the energy performance of buildings, republished. Under article 3, a building whose energy consumption is nearly zero is a building "with a very high energy performance, in which the energy consumption needed to ensure the energy performance is nearly zero or very low" (our translation).

The law does not stop at this qualitative wording. Article 17 paragraph (3) sets a quantifiable threshold: the share of energy from renewable sources must be at least 30% of the total primary energy consumed by the building, calculated according to the methodology in force. It is important to note that this 30% threshold applies, according to the text of the law, regardless of the function of the building (residential or non-residential) and regardless of the area where it is located — the law does not introduce, under this heading, thresholds differentiated by climate zone.

For an auditor, the distinction matters in practice: nZEB is not a marketing label or an "ambitious" performance level that the client may choose optionally. It is a minimum legal requirement for certain categories of new buildings, verifiable by calculation and documentable through the energy performance certificate.

Since when it is mandatory for new buildings

The republished Law 372/2005 sets two distinct deadlines, both tied to the issue date of the building permit, not to the date of acceptance:

• New buildings, in general — those for which acceptance at completion of works is based on building permits issued starting 31 December 2020 must be nZEB buildings.
• Buildings owned or administered by public authorities — the deadline is earlier, building permits issued after 31 December 2018.

In practice, for any new building recently taken into work, the nZEB threshold is no longer an exception to be checked, but the rule from which the calculation starts. The difference in treatment between public buildings and the rest of the built stock remains relevant mainly in mixed projects, where an auditor may have in the same complex buildings with different legal regimes and, implicitly, with different application deadlines.

What Mc 001-2022 requires in practice

The methodology for calculating the energy performance of buildings, reference Mc 001-2022, was approved by Order MDLPA no. 16/2023 and published in the Official Gazette no. 46 of 17 January 2023 (technical annex, in no. 46 bis). The order entered into force gradually: the general rule is 30 days from publication, that is from 16 February 2023, but the provisions of Chapter 2 — the thermal envelope of the building, subchapters 2.6-2.12 — and of Chapter 3 — the assessment of energy consumption for installation systems without renewable sources — had an entry-into-force deadline of 180 days from publication, that is from summer 2023. For certificates issued in 2026, all these provisions are already fully applicable.

In terms of content, Mc 001-2022 treats nZEB not as a separate chapter, but as the reference level against which every new building assessed is measured. For the building assessed, the methodology requires compliance with maximum primary energy consumption limits — a reference level close to zero, covered predominantly from renewable sources, according to the 30% threshold set by law. Concretely, this translates into requirements on three levels:

• The building envelope — a level of thermal insulation high enough for the energy demand for heating and cooling to remain low before active systems intervene; the methodology details how heat transfer through the envelope is calculated, but the concrete level results from the calculation specific to each building, not from a single threshold applicable to all typologies.
• The installation systems — the efficiency of heating, cooling and domestic hot water systems, while mechanical ventilation becomes mandatory for non-residential buildings where n50 < 1,5 (Mc 001-2022, §2.2.3.3).
• Renewable sources — covering at least 30% of the total primary energy through renewable sources (photovoltaic panels, heat pumps, solar thermal, biomass, depending on the technical solution chosen), a threshold set by law and taken over as such in the methodological calculation.

A necessary clarification here: the exact value of the primary energy reference level, expressed in kWh/m²/year, differs according to the category of the building and the climate zone and is read from Mc 001-2022, Tab. 2.10a, which gives the thresholds for the five climate zones (I–V), not from a single value valid across the whole territory; the table in the application reproduces them by zone. Any figure of this kind must be read from the normative table and from the result of the calculation under Mc 001-2022, not taken as a fixed standard — which is exactly why the calculation engine remains the only source of truth, and an auditor should not rely on "as a rule" figures circulated informally in the profession.

How it is verified and certified through the CPE

Compliance with nZEB requirements is not declared, it is calculated and documented. The Energy Performance Certificate (CPE), issued under Mc 001-2022, is the instrument by which the auditor demonstrates — for the building assessed — both the energy class resulting from the calculation and, for new buildings, compliance with the minimum threshold of 30% energy from renewable sources imposed by law for nZEB status.

In practice, verification involves going through the whole energy performance calculation — envelope, systems, contribution from renewable sources — and generating the documents that accompany the certificate: Annex 1, Annex 2 and the calculation summary. These documents must reflect coherently the input data of the building and the result of the calculation, including the real share of renewable energy obtained, not an assumed one.

What this means for an auditor at Step 6

In the workflow of an energy audit, generating the final documents — Step 6 — is the moment when all the data entered earlier (envelope, systems, renewable sources) is turned into the CPE, Annex 1, Annex 2 and the calculation summary, ready for issue. For a new building subject to nZEB requirements, this step is not merely an administrative formality: it is the moment when the auditor checks, in black and white, whether the result of the calculation actually confirms the nZEB status declared by the designer — including the percentage of energy from renewable sources resulting from the calculation, not only from the design.

A frequent error at this step is treating nZEB as a box ticked at the start of the project, without rechecking at the end of the calculation, when the actual execution data (installed equipment, collection surfaces, declared efficiencies) may differ from those of the design phase. The documents generated at Step 6 are the ones that remain associated with the building in the long term, which is why the coherence between the calculation and the reality on site deserves to be checked explicitly before issue, not assumed.

For an energy audit that goes coherently through all the steps — from building data to the CPE, Annex 1, Annex 2 and the calculation summary under Mc 001-2022 — you can see the complete workflow in the Zephren calculation program.