Heat Loss Indicator: the number that decides your heat pump grant
If your home was built before 2007, SEAI will only fund a heat pump once it is satisfied the house holds its heat. The test is the Heat Loss Indicator, or HLI: a BER with an HLI of 2.3 or less passes; otherwise you need a technical assessment, and possibly insulation work, first.
What the Heat Loss Indicator measures
The HLI is how much heat a house loses, per degree of difference between inside and outside, for each square metre of floor area. Its unit is watts per kelvin per square metre, written W/(K·m²). It is worked out in the BER assessment from the fabric of the house: walls, roof, floor, windows, doors and draughts. A lower number means a house that holds its heat better.
It matters for heat pumps because a heat pump delivers heat gently, at a lower temperature than a boiler, over long hours. In a leaky house it runs flat out, costs a lot to run, and may not keep up on the coldest days. The HLI rule is SEAI's way of not funding that outcome.
The rule
| Home | What SEAI requires |
|---|---|
| Built before 2007 | A technical assessment, unless you have a valid BER showing an HLI of 2.3 or less. The assessment must be done before you apply for the grant. |
| Built in 2007 or later | No technical assessment required. You can still choose to have one, and fabric upgrades are not mandatory. |
SEAI pays €200 towards the technical assessment. The assessor measures the heat loss, tells you whether the house is ready for a heat pump, and if not, which fabric upgrades would bring it under the line.
Where to find your HLI
It is calculated as part of a BER assessment, but it is not the letter grade on the certificate, and a good BER grade does not guarantee a low HLI (a house with a big solar panel array can rate well while losing a lot of heat). Ask the assessor who did your BER for the figure. If your BER is old or you never had one, a new BER produces it; SEAI's median cost for a BER in 2026 is about €280.
If your home is above 2.3
- The usual fixes are attic insulation, wall insulation and draught-proofing, in roughly that order of cost-effectiveness. SEAI has separate grants for each.
- Do the fabric work before the heat pump, not after. It lowers the heat loss, which lowers the size of heat pump you need and the radiators it needs, which lowers the quote.
- The One Stop Shop route has more flexibility. Since July 2026 SEAI has run a pilot that relaxes the HLI requirement for heat pumps installed as part of a whole-house retrofit through a One Stop Shop, the Community Energy Grant or the Warmer Homes Scheme. For the individual heat pump grant the 2.3 threshold still applies.
Why it matters beyond the grant
Even where no assessment is required, the heat loss of the house is what decides your running cost. A quote that comes with a room-by-room heat loss calculation is a design; one without is a guess. It is the first item on our quote checklist, and the running costs page shows how much the answer moves.
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