Every house advertised for sale must show a BER, and the seller has to hand over the certificate and the advisory report. Most buyers look at the letter and stop. The letter is the least useful page.
The scale
A1 is the best, G the worst. The number underneath, kWh per square metre per year, is what the letter summarises: under 25 for A1, over 450 for G. A 1970s semi with no insulation upgrade is typically D or E. The scale was tightened in 2026, so a certificate issued before then can read one band better than the same house would today. Check the date of issue.
The advisory report
This is the assessor’s list of what they saw and what each upgrade would do. Walls, roof, floor, windows, heating, ventilation, each with a current and a potential rating. It tells you whether an F is an F because of a single 1990 boiler or because the house is solid-wall with single glazing. The first is a €4,000 fix. The second is a deep retrofit. Same letter, very different purchase.
Money
Green mortgage rates from the main lenders need a B2 or better and are worth several thousand euro over the term, so a B3 house that could reach B2 with attic insulation is a real saving. At the other end, SEAI grants cover part of a retrofit; a One Stop Shop deep retrofit on a typical semi runs from €25,000 upwards after grants. Price that in. A seller cannot argue with their own advisory report.
Checking
The SEAI register lets you look up a certificate by its number. The report on this site pulls the certificate and the advisory report for the Eircode, translates the rating to the 2026 scale and attaches both PDFs, so you have them before the viewing rather than after the offer. By area: BER ratings by county and town.