Ireland's housing stock is at a crossroads: gas boilers are being phased out for new builds from 2025, and the government's retrofit programme is pushing heat pumps as the primary replacement for existing homes. But the economics are not straightforward. Whether a heat pump is cheaper than a gas boiler in 2026 depends on your home's insulation, your usage pattern, and which energy tariff you choose. This guide works through the real numbers.
How Each System Works
A gas boiler burns natural gas to produce hot water for radiators and domestic hot water (DHW). It is a direct energy conversion — gas in, heat out — with a typical efficiency of 85–92% for a modern condensing boiler.
A heat pump moves heat from outside air (or the ground) into your home using a refrigerant cycle powered by electricity. The key metric is the Coefficient of Performance (COP): a COP of 3.5 means 3.5 kWh of heat is delivered for every 1 kWh of electricity consumed. In mild Irish winters, air-to-water heat pumps typically achieve a seasonal COP of 3.0–4.0.
The heat pump's efficiency advantage is significant on paper — but it must be weighed against the price difference between electricity and gas. In Ireland in 2026, electricity costs roughly 5–6 times more per kWh than gas, so a heat pump needs a COP of 5–6 to break even on pure energy cost. In practice, COP of 3–4 means heat pumps are slightly more expensive to run per unit of heat in a poorly insulated home — and cheaper in a well-insulated home where lower flow temperatures allow higher COP.
Installation Costs in 2026
| System | Installed cost | SEAI grant | Net cost | |--------|---------------|-----------|---------| | Gas boiler (replacement) | €2,500–€4,000 | None | €2,500–€4,000 | | Air-to-water heat pump | €12,000–€18,000 | Up to €6,500 | €5,500–€11,500 | | Ground source heat pump | €18,000–€25,000 | Up to €6,500 | €11,500–€18,500 |
The SEAI heat pump grant — up to €6,500 for air-to-water systems — meaningfully closes the gap. But the net installation cost of a heat pump remains €3,000–€7,000 more than a like-for-like gas boiler replacement, even after the grant.
For homes replacing an end-of-life boiler, the question is whether the long-term running cost savings justify the higher upfront investment.
Running Costs: Side by Side
Using a typical Irish three-bed semi-detached with 15,000 kWh annual heating demand:
Gas boiler:
- Gas unit rate: ~6.5c/kWh (Bord Gáis or Flogas variable rate 2026)
- Boiler efficiency: 90%
- Effective cost per kWh of heat: ~7.2c
- Annual heating cost: ~€1,080
Air-to-water heat pump (well-insulated home, COP 3.5):
- Electricity unit rate: 23c/kWh (standard variable tariff)
- Effective cost per kWh of heat: ~6.6c
- Annual heating cost: ~€990
Air-to-water heat pump (night rate tariff, COP 3.5, running overnight):
- Night rate electricity: ~10c/kWh
- Effective cost per kWh of heat: ~2.9c
- Annual heating cost: ~€435
The night rate scenario is the key insight: a heat pump on a night rate tariff can cut annual heating costs by 60% compared to a gas boiler. This requires a well-insulated home with sufficient thermal mass (underfloor heating or radiators sized for low-temperature heating) and a smart heating controller.
BER Rating Impact
A heat pump installation typically improves a home's BER rating by 1–2 grades — from a D1 to a C2 or B3. BER improvements directly affect:
- Mortgage rates — green mortgages from AIB, Bank of Ireland, and EBS offer 0.1–0.3% rate reductions for homes with BER B3 or better
- Property value — research from the ESRI suggests each BER grade improvement adds 2–4% to property value
- Rental yield — higher BER ratings reduce void periods as tenants increasingly prioritise energy efficiency
The gas boiler, even a new condensing one, contributes far less to BER improvement than a heat pump.
Which Homes Suit Heat Pumps?
Heat pumps work best in:
- Well-insulated homes — walls, roof, and floor insulated to modern standards. Running a heat pump in a leaky house is expensive and inefficient.
- Homes with underfloor heating — underfloor systems operate at 35–45°C flow temperature, which maximises COP. Older radiator systems typically need to run at 55–65°C, reducing efficiency.
- Homes without gas connection — replacing an oil boiler or storage heaters with a heat pump offers the most compelling economics.
- New builds — designed from the ground up for heat pump efficiency.
Heat pumps are a poor fit for:
- Solid-wall Victorian or Georgian homes without external insulation
- Homes with old, undersized radiators
- Homes where there is no budget for insulation upgrade alongside the heat pump
SEAI will not approve a heat pump grant for a home that does not meet minimum insulation standards — a practical acknowledgement of this constraint.
The Verdict
In a well-insulated home on a night rate tariff, a heat pump is clearly cheaper to run than a gas boiler. The break-even on installation cost versus a replacement boiler is typically 8–12 years after grant. The break-even over a boiler that still has 10 years of life left is longer, but the regulatory trajectory — carbon tax increases, gas network charges, eventual phase-out — favours moving to a heat pump sooner.
In a poorly insulated home, a gas boiler is currently cheaper to run. The correct sequence is: insulate first (claim SEAI insulation grants), then install the heat pump, then switch to the right electricity tariff.
If you are replacing a gas boiler in a well-insulated home, 2026 is an excellent time to make the switch — grants are high, contractors are competing, and electricity tariffs specifically designed for heat pump users are now available from several Irish suppliers.
Find the best electricity tariff for a heat pump home — including night rate and smart tariff options.
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