Which detached houses are closest to an A or B?

The newer ones. In published BERs for sale and letting, 55% of detached houses built 2005–2010 are rated A or B, against 4% of detached houses built before 1940. How high a home can go depends on the house.

What one job most often gets a detached house under the heat pump line?

Built before 1940: insulating the walls (5% of those above it). Built 1940–1969: insulating the walls (3% of those above it). Built 1970–1989: replacing the windows (8% of those above it). Built 1990–2004: replacing the windows (45% of those above it). Built 2005–2010: replacing the windows (55% of those above it).

How to get a detached house to an A or B

Age decides most of it: 24% of detached houses built 2005–2010 are B2 or better in published BERs, against 2% of detached houses built before 1940. How high a home can go depends on the house.

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A single-storey rural bungalow with two cream-rendered front gables, a red-brick recessed porch with a red door, a slate roof and a large lawn in front, under a cloudy sky. — Twin gable bungalow to east of Doon village · Neil Theasby · CC BY-SA 2.0 · Photo credits

By age

How close detached houses are to an A or B, by age, and the job that most often gets them over the heat pump line
Built	A or B now	Under the heat pump line	One job that most often crosses it
before 1940	4%	4%	Insulating the walls (5%)
1940 – 1969	6%	6%	Insulating the walls (3%)
1970 – 1989	8%	8%	Replacing the windows (8%)
1990 – 2006	19%	34%	Replacing the windows (45%)
2007 – 2010	55%	84%	Replacing the windows (55%)

Certificates for a sale or letting, January 2019 to September 2026: 14,652 built before 1940, 9,534 built 1940–1969, 16,107 built 1970–1989, 20,269 built 1990–2004, 11,137 built 2005–2010. The last column is the share of homes above the line that the one job brings under it. SEAI BER Research Tool, file of 26 September 2026 (CC BY 4.0 (SEAI)). A pattern across similar homes, not a fact about yours.

The detail

The two lines that matter

The heat pump line: a BER that shows the house holds heat well enough (a heat loss indicator of 2.3 or less) means no technical assessment before the heat pump grant.
“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).” SEAI: Heat pump systems grant, read 25 Sept 2026
The windows grant asks for the same line after the works.
“The property must meet a Heat Loss Indicator (HLI) value of 2.3” SEAI: Windows and doors grant, read 13 Jul 2026
The B2 line: SEAI’s One Stop Shop scheme asks for a B2 after the works, plus a heat pump or a big cut in the energy the house uses.
“Your home must achieve a minimum post works BER of B2, plus either have installed a heat pump or achieved a primary energy uplift of 100 kWh/m²/yr.” SEAI: One Stop Shop: multiple energy upgrades (grant table), read 30 Apr 2026
B2 is the lower half of the old B band.
“B2 ≤ 125” Source: CSO Domestic BERs Q2 2026 — background notes, read 27 Sept 2026
Certificates since 24 May 2026 use a new scale with a single B, which covers a little more than the old B2. The figures here are from certificates on the old scale.
“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).” Source: CSO Domestic BERs Q2 2026 — background notes, read 27 Sept 2026