What nZEB means when buying a new house

A legal standard, not a marketing claim

nZEB stands for nearly zero-energy building. In Romania, the standard is defined by Law 372/2005 on the energy performance of buildings and is mandatory for all new buildings with permits issued after 31 December 2020.

A new house, properly permitted in 2025 or 2026, must be nZEB by law. It is not a developer's option and it is not an upgrade. What separates one project from another is not whether the standard applies, but how rigorously it is implemented and documented.

What the standard actually requires

nZEB has two conditions, verified by calculation by a certified energy auditor:

First: very low primary energy consumption. The house must stay below strict consumption thresholds set by the national calculation methodology. In practice, this is achieved through the thermal envelope (correctly dimensioned insulation on walls, roof and foundation slab, high-performance windows, elimination of thermal bridges) and through efficient building systems.

Second: energy from renewable sources. A share of the house's consumption must be covered by renewable sources produced on-site or nearby.

A heat pump is a renewable source

Both EU and Romanian legislation recognise aerothermal energy, the heat drawn from the outside air, as a renewable source. An air-to-water heat pump consumes one kilowatt of electricity and delivers three to four kilowatts of heat; the difference is renewable energy captured from the environment.

This is why, in most new houses in Romania, the heat pump alone meets the 30% renewable threshold, without a single panel on the roof. A house with a well-executed thermal envelope and an air-to-water heat pump is nZEB in the full legal sense.

Photovoltaic panels are a valuable addition: they cut the electricity bill and can generate income under Romania's prosumer scheme. But they are a separate decision from the standard, one each owner can take at their own pace.

nZEB and “a house with solar panels”: two different things

A poorly insulated house remains an inefficient house, no matter how many panels sit on the roof. The right order is the envelope and the systems first, then, optionally, self-generation.

What to check before buying

Regardless of developer or location, these are the questions that separate a rigorously implemented nZEB from a box-ticking one:

• The energy performance certificate: ask for it. It states the energy class, the primary energy consumption, and the share of renewable sources.
• The heating source: which unit is included in the price, its capacity, and who covers the warranty.
• The envelope build-up: thickness and type of insulation on walls, roof and floor slab; the windows and the glazing specification.
• Solar readiness: whether the cable routes and the distribution board allow panels to be installed later without damage to finishes.

A serious developer answers all four with documents, not with promises.