What changed on 24 May 2026
The Building Energy Rating got a new scale this summer. The Central Statistics Office put it in one line:
CSO, Domestic BERs Q2 2026: "On 24 May 2026 the Building Energy Rating (BER) scale was modified in line with new EU wide regulations under the Energy Performance of Buildings Directive (EPBD). The scale has been simplified from fifteen points to eight (A0, A, B, C, D, E, F, G)."
The law that made the change, S.I. 168 of 2026, says the same in its own words:
S.I. 168/2026, explanatory note: "The existing alpha numerical system from A1 to G will be simplified to use only letters and the previous subdivisions shall no longer apply."
So B1, B2 and B3 are all just B now, and the same for A, C, D and E. On top there is a new grade, A0:
CSO: "an A0 rating (lowest primary energy usage, with zero fossil fuel demand and carbon emissions)"
It is rare so far. The CSO's headline in August:
CSO, 26 August 2026: "Over 3,000 dwellings received the new highest BER rating of A0 as of Q2 2026"
New certificates also carry more than the letter:
S.I. 168/2026, explanatory note: "Additional metrics relating to energy usage, global warming potential and greenhouse gases will be reported on the new BER certificates issued."
Your old rating against the new letters
A BER is a number first: the energy the home needs, in kWh per square metre a year. The letter is the band that number falls in. These are the CSO's two tables, side by side, each line as the CSO printed it:
| Letter | Old scale, before 24 May | New scale, from 24 May |
|---|---|---|
| A | A1 ≤ 25, A2 ≤ 50, A3 ≤ 75 | A0 ≤ 42*, A ≤ 75 |
| B | B1 ≤ 100, B2 ≤ 125, B3 ≤ 150 | B ≤ 150 |
| C | C1 ≤ 175, C2 ≤ 200, C3 ≤ 225 | C ≤ 225 |
| D | D1 ≤ 260, D2 ≤ 300 | D ≤ 275 |
| E | E1 ≤ 340, E2 ≤ 380 | E ≤ 325 |
| F | F ≤ 450 | F ≤ 375 |
| G | G > 450 | G > 375 |
The asterisk on A0 is the CSO's: "Also meets criteria for Zero Emission Building (ZEB) defined in directive." Each row is a letter's band on each scale, not a translation: a home's number falls in one old grade and one new grade, and below C those can be different letters.
From C up, nothing moved but the names:
CSO: "The energy thresholds between ratings is identical for ratings of C and above in both scales."
Below C, the lines moved. The bottom of the scale got tighter, so the same number can earn a lower letter on a new certificate. Worked out from the two tables:
- An old D2 (D2 ≤ 300) now spans two letters: D ≤ 275 and E ≤ 325. The top part of the old D2 is an E today.
- An old E1 (E1 ≤ 340) spans E ≤ 325 and F ≤ 375.
- An old E2 (E2 ≤ 380) spans F ≤ 375 and G > 375.
- An old F (F ≤ 450) is all G on the new scale, because G > 375.
A new assessment can also give a different number from the old one, for other reasons: the house may have changed, and the assessor works from what they can see and the paperwork you show them. What a rating cert costs has the papers worth digging out first.
Your certificate still counts
You do not need a new certificate because the scale changed:
CSO: "BERs awarded before 24 May 2026 will remain valid for ten years and are included in the tables of this release."
The CSO adds when that stops:
CSO: "They become invalid if material changes are made to the dwelling during that period."
When the CSO counts homes, it reads an old grade as its new letter:
CSO: "To allow data from both scales to be used together, ratings from the old scale have been converted directly to their equivalent letter in the new scale."
So an old B3 is counted as a B, and an old D2 as a D, even where a new assessment of the same house might come out lower.
What it means for grants and mortgages
Most SEAI grants for single jobs do not ask for a letter. What matters for the heat pump is the heat loss figure on the certificate, not the grade:
SEAI, heat pump systems: "You do not need one if your valid BER says your Heat Loss Indicator is equal to or less than 2.3 W/(K.m2)."
The One Stop Shop scheme, for a whole-house upgrade, does ask for a letter. Its page now says B, where it used to say B2:
SEAI, One Stop Shop: "Your home must achieve a minimum post works BER of B, plus either have installed a heat pump or achieved a primary energy uplift of 100 kWh/m²/yr."
SEAI's page on the new scale says the improvement it expects for grants has not changed, only the label. We could not fetch that page to check it word for word, so when a One Stop Shop quotes you a target, ask them which line they are working to. Our improve-ber pages measure against the old B2, the stricter line.
Green mortgages changed in the same way: AIB, for one, now takes the old A1 to B3 on a certificate from before 24 May, or A0, A or B on one from after. Green mortgage rates has each lender's terms.
What to do with this
If you have a certificate, find the number on it, not just the letter, and read it against the table above. If your home sits near the bottom of a band below C, a new certificate after works will show whether the work moved it across a line.
Check my home puts the work in the right order for your house type and age, with every grant SEAI pays for each job.