The worse the rating, the faster it pays
We worked out what a full upgrade costs for every common kind of Irish home. The homes that look worst on paper are the ones where the money comes back quickest — because there is more waste to stop.
A home rated F or G earns it back in about 5 years. One rated D takes 7 years.

The twenty most common homes
| Home | Homes | The work | Grant | You pay | Pays back in |
|---|---|---|---|---|---|
| A 1990s detached house on oil, rated CEnergy rating C | 47,829 | €16,500 | €12,500 | €4,500 | 7 years |
| A 1990s semi-detached on gas, rated CEnergy rating C | 37,798 | €16,800 | €12,500 | €4,300 | 11 years |
| A 1990s semi-detached on oil, rated CEnergy rating C | 29,131 | €16,800 | €12,500 | €4,300 | 11 years |
| A 1970s–80s detached house on oil, rated CEnergy rating C | 24,045 | €19,000 | €10,300 | €8,900 | 15 years |
| A 1990s apartment on electric heating, rated CEnergy rating C | 23,787 | €10,100 | €5,500 | €4,600 | 4 years |
| A 1970s–80s detached house on oil, rated DEnergy rating D | 23,707 | €36,400 | €19,000 | €16,300 | 9 years |
| A pre-1970 detached house on oil, rated F/GEnergy rating F/G | 21,637 | €42,400 | €23,000 | €18,100 | 5 years |
| A 1990s apartment on electric heating, rated DEnergy rating D | 21,468 | €10,100 | €5,500 | €4,600 | 4 years |
| A 1990s terrace house on gas, rated CEnergy rating C | 20,620 | €15,000 | €12,500 | €2,500 | 8 years |
| A 1990s apartment on gas, rated CEnergy rating C | 19,505 | €10,100 | €9,500 | €600 | 2 years |
| A 1970s–80s terrace house on gas, rated CEnergy rating C | 17,875 | €15,000 | €12,500 | €4,300 | 11 years |
| A 1990s detached house on oil, rated DEnergy rating D | 15,504 | €31,100 | €19,000 | €12,300 | 10 years |
| A pre-1970 terrace house on gas, rated CEnergy rating C | 15,252 | €15,000 | €12,500 | €4,300 | 10 years |
| A pre-1970 terrace house on gas, rated DEnergy rating D | 14,573 | €23,300 | €15,900 | €7,400 | 9 years |
| A 1970s–80s semi-detached on gas, rated CEnergy rating C | 14,454 | €16,800 | €12,500 | €6,900 | 14 years |
| A pre-1970 detached house on oil, rated DEnergy rating D | 13,321 | €28,000 | €19,000 | €9,500 | 7 years |
| A pre-1970 detached house on oil, rated EEnergy rating E | 12,266 | €36,700 | €21,000 | €15,100 | 5 years |
| A 1990s detached house on gas, rated CEnergy rating C | 11,482 | €16,500 | €12,500 | €5,000 | 9 years |
| A pre-1970 terrace house on gas, rated EEnergy rating E | 10,967 | €32,100 | €17,700 | €14,400 | 8 years |
| A 1970s–80s semi-detached on oil, rated DEnergy rating D | 10,819 | €29,300 | €17,300 | €11,800 | 11 years |
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Why it works out that way
A home rated F or G is burning far more than it needs to. The work costs more, but it stops a much bigger bill, so the money comes back sooner. A home already rated B has little waste left to stop, so the same spend takes far longer to earn out.
Age is most of it. 3 in 10 homes built before 1970 are rated F or G; among those built in the 1990s and early 2000s it is closer to 1 in 100. The oldest houses are where both the waste and the saving are.
2025 medians (n=47,067 upgrades; OSS n=1,406). 2026-07-01. BER file 2026-09-08. DEAP standard occupancy.