BER Ratings Explained: the New A0 to G Scale for New Homes

A Building Energy Rating (BER) places an Irish home on a scale from A0 to G by its calculated primary energy use per square metre per year. Since 24 May 2026 this simplified scale has replaced the A1 to G bands; A0 marks the most efficient homes, with no fossil fuels. A registered assessor calculates the rating in DEAP, and several lenders offer green mortgage rates for high BERs.

The BER is the energy label of an Irish home: you see it on property listings, your lender asks for it, and for a new home it shows how the design performs. Behind the letter is a calculation of primary energy per square metre, made with a fixed method so homes can be compared. This guide explains the bands, what moves a rating up or down, what new homes achieve under Part L, and how to read the certificate.

A0–G

the simplified BER scale in force since 24 May 2026, aligned with the EU

the top band, for the most efficient homes that use no fossil fuels

20%

renewable energy ratio Part L requires for a new home

What do the BER bands mean?

The BER shows the calculated primary energy a home uses per square metre per year for space heating, hot water, ventilation, pumps and lighting, under standard occupancy. Primary energy includes the losses in producing and delivering the energy, and the certificate also shows the CO₂ emissions.

Since 24 May 2026 the scale runs from A0 to G. SEAI introduced the simplified scale to align Ireland's energy performance bands with other European countries, and A0 marks the most energy-efficient homes that do not use fossil fuels. Certificates issued before that date keep the former A1 to G bands and their original ten-year validity, unless material changes to the home invalidate them. The current upper limits in kWh/m²/yr are A: 75; B: 150; C: 225; D: 275; E: 325; and F: 375. G is above 375. A0 requires no more than 42 kWh/m²/yr and must also meet the zero-emission building criteria.

Source: SEAI, Building Energy Rating.

What BER does a new home get?

New homes must meet the nearly zero energy building (NZEB) standard of Part L. It sets limits on the energy and carbon performance of the design compared with a reference home, and requires a renewable energy ratio of 20%. Where a new home lands on the scale comes from the DEAP calculation of its design. Very low heating demand, efficient hot water, heat recovery ventilation and solar panels all raise the rating, and the top band A0 is reserved for the most efficient homes that use no fossil fuels.

The rating comes from the design and the installed systems, calculated in SEAI's Dwelling Energy Assessment Procedure (DEAP) by a registered BER assessor. A provisional rating can be issued from the plans; the final BER follows completion.

Key Takeaway

A BER compares homes on the same method, which makes it useful when you buy or borrow. For a new home, ask your assessor to model the design early: changes are cheap on paper and expensive after the house is built.

Why does the BER matter for your mortgage?

Several Irish lenders offer green mortgage rates for homes with a high BER; each lender sets its own qualifying bands. The rating is also part of the completion documents a lender asks for before the final drawdown. A BER is required when a home is offered for sale or rent, and a new home normally needs one before it is occupied; a standalone building with a total useful floor area under 50 m² is exempt from the statutory requirement, but a lender may still ask for a rating.

How do you read a BER certificate?

The band and the number: the letter and the kWh/m²/yr figure behind it.
The CO₂ indicator: the emissions per square metre per year.
The floor area: the DEAP floor area, which may differ from a brochure figure.
The advisory report: recommendations that would improve the rating.

Where do BioBuilds homes stand?

BioBuilds' standard MODULAR homes are built on a Passivhaus-certified building system, with a heating demand target of around 15 kWh/m² per year calculated with the Passivhaus method. Infinity has a separate energy specification. The Passivhaus method and DEAP use different floor areas and assumptions, so the figures are not directly comparable. The BER of a specific home is calculated in DEAP for that project by a registered assessor. To see the models and Irish prices, configure your home.

Frequently Asked Questions

A new home must meet the NZEB standard of Part L, and its band on the A0 to G scale comes from the DEAP calculation of the design and the installed systems. Very low heating demand, efficient hot water, heat recovery ventilation and solar panels all raise the rating; A0 marks the most efficient homes that use no fossil fuels.

A registered BER assessor calculates it in SEAI's Dwelling Energy Assessment Procedure (DEAP) from the design and the installed systems, under standard occupancy. It covers space heating, hot water, ventilation, pumps and lighting, and shows primary energy and CO₂ emissions per square metre per year.

Generally yes. A BER is required when a home is offered for sale or rent, and a new home normally needs one before occupation; a provisional BER can be issued from the plans. A standalone building under 50 m² of useful floor area is exempt from the statutory requirement, though a lender may still want one.

Often, yes. Several Irish lenders offer green mortgage rates for homes with a high BER. Check the current conditions with lenders, because rates and qualifying bands change, and the scale itself changed on 24 May 2026.

Andreea B.

Client Experience Lead

Certified Passive House Consultant with 8 years experience in timber-frame construction and prefabricated housing. Helping families across Europe build smarter, healthier homes.