Gas vs Heat Pump Calculator
Should you keep your gas boiler or switch to a heat pump? Compare installation costs, running costs, and CO₂ emissions over time.
Enter Your Values
Using shared profile · 3,500/mo · EUR — edit on Dashboard
Heat energy needed — not gas/electricity consumed
Coefficient of Performance — output ÷ input
Results update automatically as you change values.
What-If Scenarios
Results update instantlyCost Breakdown
15-Year Total Cost
Click chart to expand
Annual Running Cost
Click chart to expand
Side-by-Side Comparison
Bars show relative size · ✓ marks the better option- Installation Cost
- €3,500
- Efficiency (output/input)
- 90%
- Energy Needed/yr
- 13,333 kWh
- Year 1 Running Cost
- €1,187
- 15-Year Energy
- €19,839
- 15-Year Total
- €25,139
- CO₂ Emissions
- 40,000 kg CO₂
- Installation Cost
- €12,000
- Efficiency (output/input)
- COP 3.5
- Energy Needed/yr
- 3,429 kWh
- Year 1 Running Cost
- €1,109
- 15-Year Energy
- €19,130
- 15-Year Total
- €32,330
- CO₂ Emissions
- 20,571 kg CO₂
| Factor | Gas Boiler Best Value | Recommended Heat Pump |
|---|---|---|
| Installation Cost | €3,500 | €12,000 |
| Efficiency (output/input) | 90% | COP 3.5 |
| Energy Needed/yr | 13,333 kWh | 3,429 kWh |
| Year 1 Running Cost | €1,187 | €1,109 |
| 15-Year Energy | €19,839 | €19,130 |
| 15-Year Total | €25,139 | €32,330 |
| CO₂ Emissions | 40,000 kg CO₂ | 20,571 kg CO₂ |
Over 15 years, the Gas Boiler costs €7191 less. Gas needs 13333 kWh/yr at 90% efficiency. The heat pump uses 3429 kWh electricity/yr at COP 3.5. The heat pump cuts 19.4 tonnes of CO₂.
Scenario Analysis
How the outcome shifts if your assumptions turn out better or worse than expected.
Higher gas prices, good insulation
At your stated values
Low gas prices, poor COP
Compare Scenarios
Pin up to 3 and see them side by sideSet your inputs, then Pin current to save this scenario. Pin a few variations to compare their scores and outcomes here.
What Moves the Needle Most
How much each factor changes your Gas: Total Cost across its full range. Period has the biggest impact.
Focus your attention on Period — getting it right matters most. Factors lower down move the result less, so rough estimates there are fine.
Confidence & Assumptions
The outcome is fairly stable across best and worst cases — this is a robust decision.
Heat Pump Total: €22,625 (worst) → €25,139 (expected) → €27,481 (best)
These are the estimates the result depends on. Adjust them (and the Advanced inputs) to match your real situation — the closer they are to reality, the more reliable your decision.
These estimates are for informational purposes only and do not constitute financial advice. Actual results may vary based on factors not captured in this calculator.
How This Calculator Works
What this calculator does
This calculator compares the total cost of heating with a gas boiler versus an air-source heat pump, including installation, energy, maintenance, and emissions.
How the calculation works
Gas consumption = heating demand ÷ boiler efficiency. Heat pump electricity = heating demand ÷ COP. We compare total costs over your analysis period with energy price inflation.
Formula
Gas kWh = Heating Demand / Boiler Efficiency Heat Pump kWh = Heating Demand / COP Total = Install + Σ (Energy × Price × inflation^t) + Maintenance
Sources & defaults
- EU energy labelling & COP guidance
Heat-pump COP and boiler efficiency defaults
- Typical retail tariff structures (standing + unit)
Standing charge × days + kWh × unit rate; inflate over the horizon
- Eurostat / national CPI
Default inflation ~2–3% unless you override it
Example
12,000 kWh heating demand: Gas (90% efficient) uses 13,333 kWh gas at €0.08 = €1,067/yr. Heat pump (COP 3.5) uses 3,429 kWh at €0.30 = €1,029/yr. Heat pump install is higher but running costs are similar.
How to Use This Calculator
- 1Enter your numbers
Fill in the inputs for Gas vs Heat Pump Calculator. Defaults are realistic starting points — replace them with your actual figures.
- 2Understand the calculation
Gas consumption = heating demand ÷ boiler efficiency. Heat pump electricity = heating demand ÷ COP. We compare total costs over your analysis period with energy price inflation.
- 3Review results and scenarios
Check metrics, cost breakdown, comparison tables, and best / expected / worst scenarios. Use sliders to stress-test assumptions.
- 4Decide with the verdict
Read the decision engine recommendation and FAQ. Example: 12,000 kWh heating demand: Gas (90% efficient) uses 13,333 kWh gas at €0.08 = €1,067/yr. Heat pump (COP 3.5) uses 3,429 kWh at €0.30 = €1,029/yr. Heat pump install is higher but running costs are similar.
Factors to Consider
- Heat pumps work best in well-insulated homes
- COP drops in very cold weather
- Government grants can reduce heat pump install cost by €3,000-10,000
- Gas prices are volatile — long-term trends favour electrification
- Radiator upgrades may be needed for heat pumps
Common Mistakes
- Comparing gas kWh price to electricity kWh without accounting for COP
- Ignoring installation cost difference
- Using nameplate COP instead of seasonal average (SCOP)
- Not factoring in insulation upgrades needed for heat pumps
Frequently Asked Questions
Is a heat pump cheaper than gas?+
Running costs are often similar, but heat pumps cost more to install. Over 15+ years with rising gas prices, heat pumps usually win — especially with government grants.
What COP should I use?+
Modern air-source heat pumps achieve SCOP 3.0-4.5. Use 3.5 as a reasonable average. Ground-source heat pumps can reach 4.0-5.0.
Can I keep my radiators?+
Maybe. Heat pumps run at lower flow temperatures (35-45°C vs 60-70°C for gas). Older radiators may need upsizing or underfloor heating.
This calculator provides estimates for informational purposes only and does not constitute financial, investment, tax, or legal advice. Always consult a qualified professional before making important financial decisions.
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