BER Ratings Explained: The A0 to G Scale
Since 24 May 2026, every new BER in Ireland is rated on a simpler scale with 8 ratings: A0, A, B, C, D, E, F and G. A0 is the best BER rating, and is only given to zero emission homes. G is the lowest rating, and is given to the least energy efficient homes. Here's what each rating means, how the new scale compares to the old A1 to G scale, and what it means for your home.
What's Your Home's BER?
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Get BER QuotesWhat is the Best BER Rating?
A0 is the best BER rating. It's a new rating for zero emission homes, introduced on 24 May 2026 under the EU Energy Performance of Buildings Directive. To be rated A0, a home must meet all of the SEAI's zero emission building criteria:
- Energy use of 42 kWh/m²/yr or less
- Carbon emissions of 5 kg CO2/m²/yr or less
- No fossil fuels used in the home, so no oil or gas boiler and no fossil fuel stove or fire
- A heat pump or solar PV panels, which the SEAI counts as being able to respond to signals from the electricity grid
- Energy needs met by renewable sources, or by grid electricity that meets the national carbon criteria
- Compliance with the Nearly Zero Energy Building (NZEB) standard
If a home uses 75 kWh/m²/yr or less but doesn't meet every one of these criteria, it's rated A instead. This means a home heated by an oil or gas boiler can't be rated A0, however well insulated it is.
A0 homes are still rare. According to the CSO, more than 12,000 homes were rated A0 between 24 May and the end of September 2026.
What is the Lowest BER Rating?
G is the lowest BER rating. It's given to homes that use more than 375 kWh/m²/yr. According to the SEAI, G rated homes typically need a lot of energy to heat and have the highest energy bills. They tend to be older homes with little insulation, which also means they're often the homes that gain the most from energy upgrades.
The BER Scale at a Glance
Your BER is based on how much energy your home needs each year for heating, hot water, ventilation and lighting, per square metre of floor area (kWh/m²/yr). The lower the figure, the better the rating.
| Rating | Energy use (kWh/m²/yr) | What it means |
|---|---|---|
| A0 | 42 or less, and meets the zero emission criteria | A zero emission home. The best BER rating. |
| A | 75 or less | Very energy efficient. Over 99% of homes built since 2020 are rated A0 or A. |
| B | Over 75, up to 150 | Good energy efficiency. B is also the minimum rating for an SEAI One Stop Shop upgrade. |
| C | Over 150, up to 225 | Average. C is the most common rating for Irish homes with a BER. |
| D | Over 225, up to 275 | Below average. Upgrades like insulation and better heating controls can make a real difference. |
| E | Over 275, up to 325 | Poor energy efficiency, with higher heating bills. |
| F | Over 325, up to 375 | Very poor energy efficiency. Usually an older home with little insulation. |
| G | Over 375 | The least energy efficient homes, with the highest energy bills. |
Energy thresholds from the SEAI's DEAP Guide. Figures on homes built since 2020 and the most common rating are from the CSO's Domestic Building Energy Ratings release for Q3 2026.
How Does the A0 to G Scale Compare to the Old Scale?
Before 24 May 2026, homes were rated on a 15 point scale from A1 to G, with sub-ratings like B2 and C3. The new scale drops the numbers and adds A0 at the top.
For ratings of C and above, the energy thresholds are exactly the same on both scales. So a home rated A1, A2 or A3 on the old scale would be an A on the new one (or an A0 if it meets the zero emission criteria), B1 to B3 would be a B, and C1 to C3 would be a C.
Lower down the scale, the new ratings are stricter. D now stops at 275 kWh/m²/yr instead of 300, and anything over 375 kWh/m²/yr is now a G, where the old G started at 450. This means some homes rated D2, E1, E2 or F on the old scale would get a lower letter on a new BER.
| Old rating | Energy use (kWh/m²/yr) | Same energy use on the new scale |
|---|---|---|
| A1 A2 A3 | 75 or less | A or A0 if it meets the zero emission criteria |
| B1 B2 B3 | Over 75, up to 150 | B |
| C1 C2 C3 | Over 150, up to 225 | C |
| D1 | Over 225, up to 260 | D |
| D2 | Over 260, up to 300 | D up to 275, E above 275 |
| E1 | Over 300, up to 340 | E up to 325, F above 325 |
| E2 | Over 340, up to 380 | F up to 375, G above 375 |
| F | Over 380, up to 450 | G |
| G | Over 450 | G |
Old ratings aren't converted to the new scale, and a new BER assessment won't always give exactly the same energy figure, especially if anything in your home has changed. Thresholds from the SEAI and CSO.
Upgraded Since Your Last BER?
If you've added insulation, new windows, a heat pump or solar panels since your last BER, a new BER could move your home into a better rating. That can help when you're selling or renting, and some lenders offer lower green mortgage rates for A and B rated homes.
Compare BER QuotesDo I Need a New BER Because the Scale Changed?
No. All BER certificates issued before 24 May 2026 remain valid for 10 years from their date of issue, and you can still use them to sell or rent your home, including when renewing a rental contract. The rules on when you need a BER haven't changed. You'll only need a new BER if your current one has expired, or if major renovations have changed your home's energy performance. See how long a BER cert is valid for.
If you're advertising a property, the advert must show the rating from the BER certificate you're using. A BER issued before 24 May 2026 is shown with the old rating (for example B2), and a BER issued since then is shown on the new A0 to G scale.
What's on a BER Certificate Since 24 May 2026?
BER certificates issued since 24 May 2026 show the new A0 to G scale and include more information than before. The certificate is now three pages long and includes:
- Your home's energy use, including its primary energy use and the energy delivered to the home
- How much of your home's energy comes from renewable sources
- Its Global Warming Potential (GWP), which measures the carbon emissions involved over the whole life cycle of the building
- Information on whether your home meets the zero emission building standard
- A QR code that links to your BER details and energy upgrade information for your home
Every BER still comes with an advisory report, which recommends upgrades to improve your rating. See our sample BER certificate for more on what's included.
BER Ratings, Grants and Green Mortgages
SEAI grants: If you're doing a full home energy upgrade through an SEAI One Stop Shop, your home must now reach a B rating after the works, instead of B2. The SEAI has confirmed that the minimum improvement in energy efficiency required hasn't changed. See BER certs for SEAI grants.
Green mortgages: Many Irish lenders offer lower fixed rates for energy efficient homes. PTSB, for example, now offers its green mortgage rate for homes with a BER of A or B. If you're buying or switching your mortgage, check which ratings your lender accepts, including on older certificates.
What is a Good BER Rating?
As a guide, B or above is a good BER rating for an existing home, while A is now the standard for new homes. According to the CSO, of the 1.4 million homes in Ireland with a BER:
- 19% are rated A0 or A
- 18% are rated B
- 30% are rated C, the most common rating
If your home is rated D or below, energy upgrades could make a big difference to your comfort and your heating bills.
How Can I Improve My BER Rating?
Your BER depends on your home's insulation, windows and doors, heating system and controls, ventilation, lighting and any renewable energy systems. The biggest improvements usually come from insulating your attic and walls, and replacing an old oil or gas boiler with a heat pump. New windows and doors, better heating controls and solar panels can also improve your rating, and SEAI grants are available for many of these upgrades.
See how to improve your BER rating and will solar panels improve my BER rating?
How Do I Find Out My Home's Rating?
If your home already has a BER, you can look it up on the SEAI National BER Register using the BER number or the MPRN number on your electricity bill. See Find Your BER Rating. If your home doesn't have a BER, or it has expired, you'll need a new BER assessment from an SEAI-registered BER assessor. You can browse local assessors in our BER assessor directory, or compare quotes from several at once.
Get Your BER Quotes Today
Ready to find out your home's rating on the new scale? Compare quotes from trusted, SEAI-registered BER assessors in your area. Requesting quotes is free, and will save you money. See how much a BER cert costs.