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Take a home needing 12,000 kWh of heat a year. A gas boiler at ~90% efficiency burns about 13,333 kWh of gas → ≈ 2.8 t CO₂e. A heat pump at a seasonal COP of 3 uses about 4,000 kWh of electricity → ≈ 0.54 t. That's roughly 81% less, or about 107 trees a year.
And the gap widens over time: gas stays gas, while the electricity a heat pump runs on keeps getting cleaner as the grid decarbonises. TreeMonkey's Compare tab lets you set your own heat demand and COP.
Source: SAP 10.2 emission factors; illustrative boiler efficiency 90%, heat-pump SCOP 3. Figures are illustrative UK equivalents.
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Frequently asked questions
What COP should I assume?
A well-designed air-source heat pump typically achieves a seasonal COP (SCOP) around 3, sometimes higher with low-temperature emitters. TreeMonkey uses 3 for illustration; a higher COP widens the saving.
Does the grid factor change the answer?
Yes — the cleaner the electricity, the bigger the heat-pump advantage. We use the SAP 10.2 electricity factor; the live grid is often lower still.