What Nearly Zero Energy Building means for your project and the most cost-effective ways to achieve compliance.
NZEB stands for Nearly Zero Energy Building. It's an EU-driven standard under the Energy Performance of Buildings Directive (EPBD) that requires all new buildings in EU member states to have very high energy performance, with the nearly zero or very low amount of energy required covered to a significant extent by energy from renewable sources.
In Ireland, NZEB requirements are implemented through TGD Part L 2019. Since 1 November 2019, every new dwelling must achieve NZEB status — there's no opt-out or exemption for smaller developments or self-builds.
In practical terms, achieving NZEB in Ireland means meeting these three targets simultaneously:
The RER requirement is the most specifically "NZEB" element — it's what distinguishes NZEB from earlier Part L standards that focused primarily on energy reduction without specifying renewable contribution.
An air-to-water heat pump in a well-insulated dwelling typically delivers an RER of 0.30–0.40 on its own — comfortably exceeding the 0.20 minimum. This is why heat pumps have become the default heating system for new construction in Ireland since 2019.
Solar PV or solar thermal panels on top of a heat pump push the RER even higher, often to 0.40–0.60. Even a modest 2kW PV array makes a meaningful contribution and provides a comfortable compliance margin.
It's technically possible to achieve NZEB with a gas boiler, but it requires significantly more renewable contribution (typically both solar thermal and solar PV) and extremely good fabric performance. Most developers have found it's more cost-effective to use a heat pump as the primary heating system.
We'll review your design and advise on the most cost-effective route to NZEB compliance.
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