From the European directive to the BOE
The concept comes from European energy policy: the directives on the energy performance of buildings established that member states' new buildings had to be nearly zero-energy, leaving the quantitative definition to each state. The Spanish transposition culminated with Royal Decree 732/2019, which rewrote the DB-HE: since its entry into application, a building complying with sections HE 0 and HE 1 in their current version is, by regulatory definition, a nearly zero-energy building.
This legal architecture has a practical consequence worth underlining: in Spain there is no specific nearly zero-energy procedure, seal or certificate. The accreditation is the project's own energy verification and the finished building's energy performance certificate. The term describes a level of requirement, not an additional procedure.
What it requires in practice
The Spanish operational definition rests on the indicators described in the article on HE 0 and HE 1: limits on total and non-renewable primary energy consumption, demand control through the envelope's global coefficient, solar control and airtightness, individual limits per element and thermal bridge treatment, all modulated by climate zone and use, with the renewable contribution of sections HE 4 and HE 5 completing the picture. No single indicator suffices, and all are verified together.
Translated into design decisions, the ordinary Spanish nearly zero-energy building shows a recognisable repertoire: envelopes with insulation appreciably above the previous generation, high-performance joinery with low-emissivity glazing, systematic attention to junctions and airtightness, ventilation designed together with energy, with heat recovery gaining ground in cold zones, and efficient generation where the air-to-water heat pump has become the dominant solution, accompanied by photovoltaics where section HE 5 requires it or the developer makes it pay. That repertoire is decided in preliminary design and detailed afterwards.
| Indicator | What it controls | Document that sets it |
|---|---|---|
| Total and non-renewable primary energy consumption | Energy used by the building, by climate zone and use | HE 0 |
| Global envelope coefficient | Heating and cooling demand | HE 1 |
| Solar control and airtightness | Summer gains and infiltration | HE 1 |
| Individual limits per element and thermal bridges | Minimum performance of each part of the envelope | HE 1 |
| Renewable contribution | Domestic hot water and photovoltaic generation | HE 4 and HE 5 |
Nearly zero-energy and Passivhaus: relatives, not synonyms
The most frequent commercial confusion around the term is its identification with voluntary high-efficiency standards, with Passivhaus as the main reference. The real relationship is kinship, not identity. Nearly zero-energy is the legal minimum: it is defined by the regulatory limits, verified with the official tools and carries no external certification. Passivhaus is a voluntary, certified standard, with requirements of its own, notably stricter on demand and airtightness, pressurisation test included, and with a results-guarantee approach the legal minimum does not pursue.
For economic analysis, the distinction is operational: the extra cost of a Passivhaus is measured against the ordinary code-compliant building, and figures circulating that mix both levels are meaningless. The cost of building a passive house, with its own ranges, is covered in the dedicated article of the construction cost cluster.
What the jump cost and what it costs today
The interesting economic question about nearly zero-energy is no longer what it costs, because it is the legal floor and no legally buildable cheaper alternative exists, but what the jump cost and where that cost sits. Analyses of the 2019 transition placed the extra cost of the tightening, relative to the previous regulatory generation, in indicative single-digit percentage ranges over the PEM (presupuesto de ejecución material, the direct construction cost) in ordinary residential, with strong variation by climate zone: the jump was larger where the starting point was laxer and the climate harsher.
That extra cost sits in identifiable items, more centimetres of insulation, better joinery, thermal bridge resolution, more sophisticated ventilation, more efficient generation, and is partially recovered in operation through the energy bill, with payback periods depending on climate, use and energy prices. For the developer, the mature reading is not about extra cost but positioning: the regulatory level is indistinguishable between competitors, and real differentiation is played out today above the minimum, in demonstrable comfort and measured consumption.
The next stage: from nearly zero to zero emissions
Nearly zero-energy is not the final station. The 2024 European directive on the energy performance of buildings introduced the zero-emission building concept as the new horizon for new construction, and the CTE reform currently going through approval, expected in the course of 2026, articulates its transposition: definition of the zero-emission building, reinforcement of renewable requirements with a new solar generation section, and a sustainability basic document incorporating the global warming potential of the building's full life cycle.
The direction is unequivocal: less consumption, fewer operational emissions and, the major novelty, attention to the carbon embodied in materials. For projects and developments with a multi-year horizon, the operational recommendation is to design with headroom over today's minimums and follow the reform's final text, because the building that complies to the millimetre today will be the first to fall short.
Frequent errors
The first is selling regulatory compliance as a distinction: every new building is nearly zero-energy by obligation, and the serious commercial argument starts above the minimum. The legal minimum does not differentiate one development from another.
The second is confusing the legal level with certified standards, with the cost distortions already described. Each standard has its own threshold and its own certification procedure.
The third is entrusting everything to the machine: nearly zero-energy rests first on the envelope, and brilliant systems on poor fabric produce buildings that comply on paper and disappoint in use. The envelope is decided first and governs the size of the equipment.
The fourth is ignoring the regulatory trajectory: budgeting today a development to be delivered after the reform with no margin over current limits is scheduling a change order. Leaving margin over current limits is prudent on long horizon developments.
Note: the extra cost ranges cited are indicative and depend on climate zone, building type and market; the applicable regulatory definition is that of the consolidated DB-HE in force and, in due course, that of the final text of the reform under approval.