The heat pump cost calculator and the 2026 heat pump cost report use one engine, so the same home always gives the same numbers. Everything is a range, because two homes of the same type can need very different systems. Nothing here is a quote: an installer's room-by-room heat loss survey decides the real figure. Every constant below is also in the downloadableassumptions file (JSON) and CSV.
Inputs and defaults
| Input | Values | Use and default |
|---|---|---|
| Property type | Detached · Semi-detached · Terraced · Bungalow · Apartment | Required. Bungalows use the CSO's detached-house figures; terraced uses mid-terrace |
| Year built | Before 1978 · 1978–1999 · 2000–2006 · 2007–2020 · 2021 or later | Required. Built or first lived in from 2021: no grant |
| Floor area | m², optional | If blank: the CSO average for the type and build period (table below) |
| BER | A0–G, an old A1–G certificate, or "don't know" | If not known: estimated from the CSO average energy value for the type and period. Old grades map to their letter (E1 → E) |
| Heat Loss Indicator | W/K·m², optional | At or below 2.3, a pre-2007 home needs no technical assessment |
| Current heating | Oil · Gas · LPG · Solid fuel · Storage heaters · Electric heaters · Other or none | Sets the fuel price, the boiler efficiency and whether boiler scrappage applies |
| Heating emitters | Radiators · Underfloor · Both | Recorded; no Irish data splits performance by emitter, so it doesn't change the figures |
| New radiators needed? | Yes · No · Not sure (default) | "Not sure" adds anything from €0 to the top of the radiator range, and shows the central heating grant as "may apply" |
Property type
- Values
- Detached · Semi-detached · Terraced · Bungalow · Apartment
- Use and default
- Required. Bungalows use the CSO's detached-house figures; terraced uses mid-terrace
Year built
- Values
- Before 1978 · 1978–1999 · 2000–2006 · 2007–2020 · 2021 or later
- Use and default
- Required. Built or first lived in from 2021: no grant
Floor area
- Values
- m², optional
- Use and default
- If blank: the CSO average for the type and build period (table below)
BER
- Values
- A0–G, an old A1–G certificate, or "don't know"
- Use and default
- If not known: estimated from the CSO average energy value for the type and period. Old grades map to their letter (E1 → E)
Heat Loss Indicator
- Values
- W/K·m², optional
- Use and default
- At or below 2.3, a pre-2007 home needs no technical assessment
Current heating
- Values
- Oil · Gas · LPG · Solid fuel · Storage heaters · Electric heaters · Other or none
- Use and default
- Sets the fuel price, the boiler efficiency and whether boiler scrappage applies
Heating emitters
- Values
- Radiators · Underfloor · Both
- Use and default
- Recorded; no Irish data splits performance by emitter, so it doesn't change the figures
New radiators needed?
- Values
- Yes · No · Not sure (default)
- Use and default
- "Not sure" adds anything from €0 to the top of the radiator range, and shows the central heating grant as "may apply"
When the floor area or BER is left blank, the calculator uses these defaults: the CSO's average floor area and average BER energy value for the type, averaged over the CSO build periods in the band.1,2
| Built | Detached | Semi-detached | Terraced | Bungalow | Apartment |
|---|---|---|---|---|---|
| Before 1978 | 140 m² · F | 127 m² · E | 92 m² · E | 140 m² · F | 55 m² · G |
| 1978–1999 | 159 m² · C | 102 m² · C | 83 m² · C | 159 m² · C | 61 m² · E |
| 2000–2006 | 196 m² · C | 108 m² · C | 96 m² · C | 196 m² · C | 71 m² · C |
| 2007–2020 | 220 m² · B | 120 m² · B | 108 m² · B | 220 m² · B | 76 m² · B |
| 2021 or later | 205 m² · A | 118 m² · A | 105 m² · A | 205 m² · A | 73 m² · A |
Before 1978
- Detached
- 140 m² · F
- Semi-detached
- 127 m² · E
- Terraced
- 92 m² · E
- Bungalow
- 140 m² · F
- Apartment
- 55 m² · G
1978–1999
- Detached
- 159 m² · C
- Semi-detached
- 102 m² · C
- Terraced
- 83 m² · C
- Bungalow
- 159 m² · C
- Apartment
- 61 m² · E
2000–2006
- Detached
- 196 m² · C
- Semi-detached
- 108 m² · C
- Terraced
- 96 m² · C
- Bungalow
- 196 m² · C
- Apartment
- 71 m² · C
2007–2020
- Detached
- 220 m² · B
- Semi-detached
- 120 m² · B
- Terraced
- 108 m² · B
- Bungalow
- 220 m² · B
- Apartment
- 76 m² · B
2021 or later
- Detached
- 205 m² · A
- Semi-detached
- 118 m² · A
- Terraced
- 105 m² · A
- Bungalow
- 205 m² · A
- Apartment
- 73 m² · A
How each figure is worked out
- Heat the home uses = metered fuel use per m² for its BER band × floor area. The CSO measured what gas-heated homes actually burned in 2022 (low) and 2021 (high); we apply the same heat need to homes on other fuels.4 We don't use the BER's theoretical energy value, which overstates older homes.
- Useful heat = fuel used × the current system's seasonal efficiency (SEAI's bands; condensing boilers assumed for homes built from 2007).
- Running cost now = fuel used × SEAI's price for the fuel.9
- Heat pump running cost = useful heat ÷ SPF × the standard electricity price (34.38c/kWh). The range pairs the least heat with the best SPF (4) and the most heat with the worst (2.5); the single figure uses the average SPF of 3.22 measured in Irish homes.9,10
- Installed cost = the published guide range for the floor-area band, plus €1,500–€5,000 for new radiators ("not sure": €0 to €5,000).5,6
- Grant = €10,500 for a house's heat pump + €2,000 if new radiators are needed + €2,000 if a qualifying system is removed (oil, gas, solid fuel, electric storage, or none). LPG and direct electric show scrappage as "may apply". Apartments: €8,500 + €1,000 + €2,000, capped at €11,500. Never more than the installed cost; nothing for homes built from 2021.7,8
- You pay = from (lowest installed − highest grant) to (highest installed − lowest grant), never below €0.
- Yearly saving = from (lowest cost now − highest heat pump cost) to (highest cost now − lowest heat pump cost).
- Payback = you pay ÷ saving, from (lowest you-pay ÷ highest saving) to (highest you-pay ÷ lowest saving). If the lowest saving is zero or less, payback is shown as "not certain", or as "likely costs more to run" when even the highest saving is zero or less. If the grant covers the whole cost, payback is 0.
Rounding: money to the nearest €10 (after the sums, never before); floor area to the nearest m²; payback to 0.1 year. Useful heat is not rounded.
Every constant
Metered fuel use (kWh per m² a year)
| BER band | kWh/m²/yr |
|---|---|
| A0, A, B | 75–88 |
| C | 86–101 |
| D | 96–112 |
| E | 103–119 |
| F, G | 104–120 |
A0, A, B
- kWh/m²/yr
- 75–88
C
- kWh/m²/yr
- 86–101
D
- kWh/m²/yr
- 96–112
E
- kWh/m²/yr
- 103–119
F, G
- kWh/m²/yr
- 104–120
Installed cost before the grant
| Home size | Range |
|---|---|
| Small home, under 90 m² | €13,000–€16,000 |
| Typical 3-bed semi-d, 90–130 m² | €15,000–€18,000 |
| 4-bed detached, 130–180 m² | €17,000–€22,000 |
| Large detached, over 180 m² | €20,000–€28,000 |
Small home, under 90 m²
- Range
- €13,000–€16,000
Typical 3-bed semi-d, 90–130 m²
- Range
- €15,000–€18,000
4-bed detached, 130–180 m²
- Range
- €17,000–€22,000
Large detached, over 180 m²
- Range
- €20,000–€28,000
These are published Irish guide ranges, not observed prices. SEAI's observed medians for comparison are in the 2026 report.
Fuel prices and efficiencies
| Fuel | Price | Efficiency, built before 2007 | Efficiency, built 2007 on |
|---|---|---|---|
| Oil | 11.72c | 60–75% | 85–97% |
| Gas | 13c | 55–75% | 85–97% |
| LPG | 17.67c | 55–75% | 85–97% |
| Solid fuel | 9.45c | 65–85% | 65–85% |
| Storage heaters | 15.42c | 90% | 90% |
| Electric heaters | 34.38c | 100% | 100% |
Oil
- Price
- 11.72c
- Efficiency, built before 2007
- 60–75%
- Efficiency, built 2007 on
- 85–97%
Gas
- Price
- 13c
- Efficiency, built before 2007
- 55–75%
- Efficiency, built 2007 on
- 85–97%
LPG
- Price
- 17.67c
- Efficiency, built before 2007
- 55–75%
- Efficiency, built 2007 on
- 85–97%
Solid fuel
- Price
- 9.45c
- Efficiency, built before 2007
- 65–85%
- Efficiency, built 2007 on
- 65–85%
Storage heaters
- Price
- 15.42c
- Efficiency, built before 2007
- 90%
- Efficiency, built 2007 on
- 90%
Electric heaters
- Price
- 34.38c
- Efficiency, built before 2007
- 100%
- Efficiency, built 2007 on
- 100%
Heat pump: SPF 2.5–4 (SEAI's range for air to water), 3.22 measured average; electricity 34.38c/kWh standard rate (Band DD). Gas and electricity prices are from SEAI's July–December 2025 price survey; oil, LPG and solid fuel are 1 July 2026 supplier prices.
Worked examples you can check by hand
The calculator's three reference homes, using its own intermediate figures. The same homes are hand-checked in our automated tests, which fail if the calculator's output changes, and they're the worked examples on the calculator and cost pages.
3-bed semi-d, 1978–1999, oil heating, BER unknown
- Floor area
- 102 m² (CSO average for the type and period)
- BER band
- C (estimated from the CSO average energy value)
- Fuel used a year
- 86–101 kWh/m² × 102 m² = 8,772–10,302 kWh
- Useful heat
- × 60–75% efficiency = 5,263.2–7,726.5 kWh
- Running cost now
- 8,772–10,302 kWh × 11.72c = €1,028–€1,207 → €1,030–€1,210
- Heat pump running cost
- 5,263.2 ÷ 4 × 34.38c = €452; 7,726.5 ÷ 2.5 × 34.38c = €1,063 → €450–€1,060; at SPF 3.22: €690
- Installed cost
- Typical 3-bed semi-d, 90–130 m²: €15,000–€18,000 + radiators €1,500–€5,000 = €16,500–€23,000
- Grant
- €10,500 heat pump + central heating €2,000 + scrappage €2,000 = €14,500
- You pay
- €16,500–€23,000 − grant = €2,000–€8,500 (lowest price − highest grant to highest price − lowest grant)
- Yearly saving
- €1,030–€1,210 now − €450–€1,060 heat pump = −€30 to €760
- Payback
- Not certain: Savings depend on your tariff and how well the system is designed, so payback on running costs alone isn't certain.
Bungalow built before 1978, oil heating, BER E1
- Floor area
- 140 m² (CSO average for the type and period)
- BER band
- E (from the certificate, E1 on the old scale)
- Fuel used a year
- 103–119 kWh/m² × 140 m² = 14,420–16,660 kWh
- Useful heat
- × 60–75% efficiency = 8,652–12,495 kWh
- Running cost now
- 14,420–16,660 kWh × 11.72c = €1,690–€1,953 → €1,690–€1,950
- Heat pump running cost
- 8,652 ÷ 4 × 34.38c = €744; 12,495 ÷ 2.5 × 34.38c = €1,718 → €740–€1,720; at SPF 3.22: €1,130
- Installed cost
- 4-bed detached, 130–180 m²: €17,000–€22,000 + radiators €0–€5,000 = €17,000–€27,000
- Grant
- €10,500 heat pump + central heating €0–€2,000 (may apply) + scrappage €2,000 = €12,500–€14,500
- You pay
- €17,000–€27,000 − grant = €2,500–€14,500 (lowest price − highest grant to highest price − lowest grant)
- Yearly saving
- €1,690–€1,950 now − €740–€1,720 heat pump = −€30 to €1,210
- Payback
- Not certain: Savings depend on your tariff and how well the system is designed, so payback on running costs alone isn't certain.
Apartment, 2007–2020, storage heaters, BER B
- Floor area
- 76 m² (CSO average for the type and period)
- BER band
- B (from the certificate)
- Fuel used a year
- 75–88 kWh/m² × 76 m² = 5,700–6,688 kWh
- Useful heat
- × 90% efficiency = 5,130–6,019.2 kWh
- Running cost now
- 5,700–6,688 kWh × 15.42c = €879–€1,031 → €880–€1,030
- Heat pump running cost
- 5,130 ÷ 4 × 34.38c = €441; 6,019.2 ÷ 2.5 × 34.38c = €828 → €440–€830; at SPF 3.22: €600
- Installed cost
- Small home, under 90 m²: €13,000–€16,000 + radiators €1,500–€5,000 = €14,500–€21,000
- Grant
- €8,500 heat pump + central heating €1,000 + scrappage €2,000 = €11,500
- You pay
- €14,500–€21,000 − grant = €3,000–€9,500 (lowest price − highest grant to highest price − lowest grant)
- Yearly saving
- €880–€1,030 now − €440–€830 heat pump = €50 to €590
- Payback
- €3,000–€9,500 ÷ yearly saving = 5.1–190 years
County statistics method
County figures come from the CSO's Domestic Building Energy Ratings Q2 2026 release: Table 8 (main space heating fuel) and Table 14 (heat pumps), covering every dwelling rated from 2009 to June 2026.11 CSO publishes 31 geographies. For the 21 counties published as one row we use CSO's whole-number percentage unchanged.5 are split: Dublin (Dublin 01–24 and Dublin County), and Cork, Galway, Limerick and Waterford (city and county). For those:
county share = Σ (row share × row's BER-rated dwellings) ÷ Σ row BER-rated dwellings
For example, Dublin's oil share = (4% × 309,255 + 9% × 105,417) ÷ 414,672 = 5.3%, shown as ≈5%. Because each row was already rounded to a whole number, the combined figure can be up to half a point out. Table 14 has no Dublin 01–24 row, so Dublin's heat pump share combines its postal districts and Dublin County. Counties are ranked on the whole number shown; equal figures share a rank. National figures are CSO's own totals, not our sum. The original rows are in the CSO Table 8 CSV, and our tests recompute every county from them.
Limits
- Ranges describe typical homes, not yours. Heat loss, the existing radiators and the installer's design decide the real cost and performance.
- Installed costs are published guide ranges. We haven't surveyed installer quotes; when we have enough anonymised quotes, we'll show them separately with the number of quotes.
- Running costs leave out standing charges, servicing, hot water from other sources and the cost of the installation. They price all heat pump electricity at the standard rate.
- Metered use comes from gas homes in 2021–2022; homes on other fuels may use more or less.
- BER statistics describe dwellings rated since 2009, not every home.
Scenarios where payback is uncertain or negative
When the heat pump's worst-case running cost is higher than the current fuel's best case, the saving range starts below zero and we don't show a payback figure. This happens most with solid fuel, efficient condensing boilers and poorly performing systems.
How we update the figures
- Grants: checked monthly and whenever SEAI announces a change; the calculator updates at once.
- Fuel prices: when SEAI publishes a new Domestic Fuel Cost Comparison.
- CSO statistics: when the CSO publishes a new BER quarter, the live county figures move on; the 2026 report keeps its Q2 2026 data.
- The 2026 report is dated and frozen: if the grant or prices change, it keeps the figures it was published with, and a new edition carries the new ones.
Spotted an error? Email hello@heatpumpinstallation.ie and we'll check it against the source.
Downloads
- Calculator assumptionsEvery constant with value, unit, use, source and checked date.Download Calculator assumptions (JSON)
- Calculator assumptionsThe same as a spreadsheet.Download Calculator assumptions (CSV)
- 2026 report figuresThe frozen figures behind the 2026 report.Download 2026 report figures (JSON)
- Data dictionaryColumn definitions for the county files.Download Data dictionary (CSV)