Ireland yet to set zero-emission building timeline

This article was originally published in issue 52 of Passive House Plus magazine. Want immediate access to all back issues and exclusive extra content? Click here to subscribe for as little as €15, or click here to receive the next issue free of charge

The revised EPBD (EU/2024/1275) was adopted in May 2024, and must be transposed into national law by 29 May 2026. Its central preoccupations are the renovation of the existing building stock, tightened performance requirements for new buildings, and the reduction of whole life greenhouse gas emissions – including embodied carbon.

Critically for new build standards, it requires member states to articulate and adopt a definition of zero emissions buildings (ZEB), replacing the nearly zero energy building (NZEB) requirement that has underpinned Part L since 2019.

In response to questions from Passive House Plus, a spokesperson for the department confirmed that a number of directive requirements had already been transposed, including Article 17(15), which prohibits subsidies for standalone fossil fuel boilers, and Article 13(10)(d), which covers building automation and control systems. Draft regulations transposing further articles are, the spokesperson says, expected shortly. On the outstanding articles, including those covering ZEBs, the response was that "work is continuing." The SEAI is also involved in transposition preparation. Questions on how Ireland intends to create a national definition for ZEB, and when a consultation process is planned, were not addressed directly.

On the face of it, the overarching requirements for ZEB in the revised directive sets a performance threshold that sits close to the passive house standard, given the definition of ZEB includes a building that has “a very high energy performance […] requiring zero or a very low amount of energy”. In addition, the directive specifies “zero on-site carbon emissions from fossil fuels” and that buildings produce “zero or a very low amount of operational greenhouse gas emissions.”

Performance gap questions for ZEB

With evidence of a performance gap in notionally low energy buildings gaining increasing media coverage, the directive also stipulates that the calculated or metered energy use “shall reflect typical energy use” for regulated loads including heating, cooling, hot water, ventilation and lighting. “Member States shall ensure that the typical energy use is representative of actual operating conditions […] and reflects the typical user behaviour.”

The directive also requires that national calculation methodologies “account for varying conditions that significantly affect the operation and performance of the system and the indoor conditions, and to optimise health [and] indoor air quality, including comfort levels”.

All of this suggests significant work will be required to improve upon Ireland’s current calculation methodology and NZEB definition, with a weight of academic research indicating suboptimal performance of notionally low energy buildings in Ireland in terms of energy use, indoor air quality and thermal comfort. A 2021 paper by Coyne and Denny found A and B rated homes used 39 per cent more energy than calculated, while the SEAI-funded nZEB101 monitoring study found NZEBs underperforming on average by one BER band.

Meanwhile, in 2025 the SEAI-funded ALIVE project found significant issues in terms of monitored indoor air quality and overheating in naturally ventilated NZEBs.

In part the answer for member states may lie in adhering to a standard which sets parameters for indoor environmental quality (IEQ), including thermal comfort and indoor air quality: EN 16798-1, which sets far more ambitious IEQ parameters than Ireland’s current approach.

The Dwelling Energy Assessment Procedure (DEAP) has been Ireland’s national methodology for dwellings since 2006. It assumes intermittent heating, with homes heated for 8 hours per day, to temperatures of 21C in the living area, and 18C in the rest of the space. In a typical Irish home, the living area represents circa 20 per cent of the total, meaning an assumed temperature of 18.6 during heated periods. Previous analysis published by Passive House Plus has demonstrated that this can translate to calculated temperatures as low as 15.5C in compliant NZEB homes during the 16 unheated hours.

Meanwhile, EN 16798-1 assumes that homes are heated 24 hours per day, and sets different temperatures bands for different IEQ categories: IEQI for occupants with special needs (children, elderly and people with disabilities; IEQII for a normal level; IEQIII for an acceptable level – albeit with the risk of reduced performance for some occupants; and IEQIV, for homes which are only in use for short times during the year. The four levels set heating season temperature bands of 21-25C (IEQI), 20-25C (IEQII); 18-25C (IEQIII) and 17-25C (IEQIV). Critically, these thresholds apply not just to living rooms, but to bedrooms and kitchens too, and deviation from these temperature bands is only briefly permitted in order to meet these classes. All in all, it appears that many homes which meet Ireland’s NZEB definition may not even meet the lowest level in EN 16798-1, IEQIV. Meanwhile, the passive house standard sets a minimum whole house temperature of 20C during the heating season, on a 24 hour per day basis.

A spokesperson for the Department of Housing, Local Government and Heritage said the department was undertaking "significant work" alongside the SEAI to prepare for transposition, and that draft regulations for further articles of the directive were expected shortly. In response to follow-up questions from Passive House Plus a Department spokesperson said: “Work on the transposition of the EPBD is ongoing and detailed technical issues will be considered as part of the ongoing development of the Articles of the Directive”.