An NZEB, or Nearly Zero Energy Building, is a house built to have a very high energy performance, with most of its low remaining energy demand met from renewable sources, as required under national building regulations transposing the EU Energy Performance of Buildings Directive. Almost all new dwellings in Ireland must now be built to this standard, typically achieving a BER in the A rating band.
NZEB stands for Nearly Zero Energy Building, a concept introduced across the EU under the Energy Performance of Buildings Directive and implemented in Ireland through amendments to Technical Guidance Document Part L. It sets a very high standard of energy performance for new buildings, requiring both a low overall energy demand achieved through excellent fabric and services design, and that a significant share of the remaining energy need is met from renewable sources.
In Ireland, new dwellings for which planning applications were made from November 2019 onwards generally must comply with the NZEB requirements. This typically translates into thick, well-detailed insulation in walls, roofs and floors, high-performance windows, careful attention to airtightness and thermal bridging, and a renewable heating solution, most commonly an air-to-water heat pump, sometimes supplemented with solar PV or solar thermal panels.
Because these requirements are demanding by the standards of much older Irish housing stock, an NZEB house will usually achieve a BER well into the A band, most often A2, and should have noticeably lower running costs for heating and hot water than a typical older home of the same size.