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What is a Nearly Zero Energy Building in Ireland?

A Nearly Zero Energy Building (NZEB) is a building with very high energy performance whose remaining low energy demand is met substantially from renewable sources, as required by EU and Irish building regulations for new construction. In Ireland this standard has applied to almost all new dwellings and many other new buildings since the relevant amendments to Part L took effect.

The term Nearly Zero Energy Building comes from the recast EU Energy Performance of Buildings Directive, which required all EU member states to ensure new buildings meet a very high energy performance standard, with the small remaining energy demand covered to a significant extent by renewable energy, including energy produced on-site or nearby. Ireland transposed this requirement through updates to the building regulations, principally Technical Guidance Document Part L for dwellings and equivalent guidance for non-residential buildings.

In practice, NZEB is not a single fixed specification but a performance-based standard: designers must demonstrate, through calculation, that a building's energy use and carbon emissions fall below defined limits, and that renewable technologies contribute a required share of the remaining demand. For homes, this is checked using the DEAP methodology; for larger or non-domestic buildings, an equivalent method (NEAP) is used.

The practical result for most new Irish homes is a highly insulated, airtight building with a heat pump or other renewable heating source, commonly resulting in a BER in the A band. For non-residential buildings such as offices, schools or commercial units, NZEB requirements apply in a broadly similar way but are assessed against non-domestic performance benchmarks rather than the domestic BER scale.

Where NZEB requirements apply

NZEB standards generally apply to:

  • New dwellings, from the relevant regulatory implementation date
  • New non-residential buildings such as offices, schools and retail units
  • Some cases of major renovation, depending on the extent of the works, under the wider EPBD framework

Whether a specific renovation project triggers NZEB-equivalent requirements depends on its scale and nature, and this should be checked with the project's architect, engineer or the local building control authority.

Difference from a BER

NZEB is a regulatory design and construction standard applied at the point a building is built or significantly renovated, while a BER is the certificate and rating that measures and communicates a building's actual calculated energy performance once complete; a building designed and built to NZEB standard will typically, but not automatically, achieve a high BER once assessed.

Sources

Last reviewed 24 August 2026. General information only — not legal or planning advice.

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