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The SAP 10.2 emission factors put grid electricity at 0.136 kg CO₂e/kWh and mains gas at 0.21. That electricity is now lower than gas is the whole reason a heat pump beats a boiler — it wasn't true a decade ago, when the grid was far dirtier.
Two figures often get mixed up: the fixed SAP factor used for compliance, and the live grid intensity (National Grid ESO), which is often lower still and changes by the hour as wind and solar rise. TreeMonkey keeps them separate and labels which is which.
Source: SAP 10.2 emission factors; National Grid ESO for live grid intensity. Figures are illustrative UK equivalents.
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Frequently asked questions
Why is the SAP electricity factor lower than gas?
Because the grid has decarbonised rapidly — lots of wind, solar and less coal. SAP 10.2 reflects that, which is why electrified heat now carries less carbon than burning gas.
Is the live grid figure different?
Yes — the real-time grid intensity varies through the day and is often below the fixed SAP compliance factor. TreeMonkey shows both so you can see the trend.