Heat Pump vs Gas Running Costs: What January 2027's Forecast Shows
Every forecast for January has gas rising faster than electricity. Here's what that means for heat pump running costs, using Cornwall Insight's and EDF's figures.
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For years, the answer to "will a heat pump save me money?" has depended heavily on one stubborn fact: UK electricity costs roughly three to four times as much per unit as gas. That gap, known in the industry as the "spark gap", is the single biggest reason heat pumps haven't always beaten a modern gas boiler on pure running costs, even with their 3-4x efficiency advantage. New forecast data suggests that gap is starting to move, and worth understanding exactly how much.
Quick answer: Cornwall Insight's latest forecast (30 September 2026) has the January to March 2027 electricity rate rising 15%, from 26.32p to 30.28p per kWh, and gas rising 22%, from 7.97p to 9.76p. Because gas rises faster, electricity goes from 3.30 times the price of gas to 3.10 times. For a heat pump against a 92% efficient gas boiler, the efficiency needed to break even on a standard tariff falls from a SCOP of about 3.0 to about 2.85. That is close to the UK field-trial median, so the average heat pump moves from just behind gas to roughly level. It is a forecast, and Ofgem confirms the real cap by 25 November.
The Numbers: Now and Forecast
The current rates are Ofgem's confirmed cap for October to December 2026. The forecasts are for January to March 2027. Both are GB averages for a home paying by Direct Debit.
| Per kWh | Now (Oct to Dec 2026) | Cornwall Insight forecast (30 Sept) | EDF forecast (14 Sept) |
|---|---|---|---|
| Electricity | 26.32p | 30.28p (+15%) | 32.61p (+24%) |
| Gas | 7.97p | 9.76p (+22%) | 10.97p (+38%) |
| Electricity ÷ gas | 3.30 | 3.10 | 2.97 |
Sources: Ofgem price cap for October to December 2026; Cornwall Insight forecast published 30 September 2026; EDF's published forecast, updated 14 September 2026. Our January 2027 price cap guide tracks the forecasts as they change.
The two forecasts differ on how big the rise will be, but they agree on the direction: gas goes up faster than electricity. That is what matters for a heat pump. Cornwall Insight's figure is the more recent of the two and it is the one we use below. It has already moved by £127 in a single update, so treat both as a direction rather than a number.
The Spark Gap, Explained
A heat pump with a SCOP (seasonal coefficient of performance) of 3 delivers about 3 units of heat for every unit of electricity. A modern gas boiler is about 92% efficient, so 1 unit of gas gives 0.92 units of heat. To match the boiler on cost, the heat pump needs a SCOP of at least the electricity-to-gas price ratio multiplied by 0.92.
The SCOP a heat pump needs to match gas on a standard tariff
- Now (October to December 2026): about 3.0
- January 2027, Cornwall Insight forecast: about 2.85
- January 2027, EDF forecast: about 2.75
Field trials put the median UK heat pump at a SCOP of about 2.8, and a well-designed system reaches 3.5 or more. So on Cornwall Insight's forecast the average heat pump on a standard tariff moves from just behind gas to roughly level, and a good installation moves further ahead. Most heat pump owners are not on a standard tariff, though. On a heat pump tariff such as Octopus Cosy the comparison was already in the heat pump's favour, and this shift helps a little more. Try your own numbers in our heat pump running cost calculator.
What This Means If You're Deciding Now
If you're replacing a dying boiler this winter
This trend strengthens the case for a heat pump over a like-for-like gas boiler swap, on top of the £7,500 Boiler Upgrade Scheme grant (£9,000 for oil and LPG homes until 31 March 2027). See our heat pump vs gas boiler comparison for the full picture.
If your current boiler is fine
One quarter's forecast isn't, on its own, a reason to replace a working boiler early: the upfront cost and disruption still need to be weighed properly. In the meantime, an electric heater in the room you use most can let you turn the whole-house heating down. Our electric heater guide shows what each type costs per hour.
If you already have a heat pump on a standard tariff
Worth checking whether a smart tariff would improve your numbers further. See our Octopus tariff comparison for the real rates available specifically for heat pump owners.
Caveats Worth Keeping in Mind
These are forecasts, not confirmed rates. Forecasters revise them as wholesale prices move, and Ofgem will confirm the January to March 2027 cap by 25 November 2026. Real running costs depend on your heat pump's SCOP, your insulation and your radiator sizing, and a poorly sized system won't benefit as much as a well-designed one. Under recent price caps, heat pumps on a standard tariff have not reliably beaten gas for most homes. This piece describes a forecast shift in that balance, not a claim that it has already reversed.
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Published September 2026, updated 10 October 2026. Current rates: Ofgem price cap for October to December 2026. Forecasts: Cornwall Insight (30 September 2026) and EDF's price cap forecast (14 September 2026). Read Ofgem's price cap page for confirmed rates. Ofgem announces the January to March 2027 cap by 25 November 2026.
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