Last Updated on October 20, 2026
Most fixed air conditioners are reversible, so the unit that cools a bedroom in July can heat it in November. This guide works out the heating with air conditioning cost UK homeowners can expect per kWh of heat and sets it against a gas boiler, using Ofgem’s October 2026 unit rates and the January 2027 forecasts.
A good unit beats gas per kWh of heat while it runs at a seasonal efficiency of about 3 or better, which suits single rooms more than whole houses.
Quick answer: At Ofgem’s October 2026 cap rates, air conditioning in heating mode costs about 5.1p to 6.1p per kWh of heat (SCOP 5.2 to 4.3), against 8.9p for a 90% efficient gas boiler. It wins for single rooms in spring and autumn. Its edge disappears if real-world efficiency falls below about 3.
Contents
- 1 Heating with air conditioning cost UK: the per-kWh maths
- 2 What will the January price cap do to heating with air conditioning?
- 3 How much does heating with air conditioning cost per hour?
- 4 Where heating with air conditioning wins
- 5 Where heating with air conditioning does not win
- 6 Best heat pump air conditioner for heating
- 7 What about installation cost, VAT and the grant?
- 8 FAQs
- 8.1 Is it cheaper to heat a room with air conditioning than with gas?
- 8.2 How much does it cost to run air conditioning on heat mode per hour?
- 8.3 Can air conditioning replace central heating?
- 8.4 Do air conditioners still heat in freezing weather?
- 8.5 Will the January 2027 price cap change the comparison?
- 9 Our Verdict
- 10 Sources
Key takeaways
- A reversible unit delivers heat for 5.1p to 6.1p per kWh, against 8.9p for a 90% efficient gas boiler and 26.3p for a panel heater.
- Break-even is a seasonal efficiency of about 3.0. Below it, gas is cheaper.
- January forecasts run from £1,999 (Cornwall Insight) to £2,185 (British Gas), with gas expected to rise faster than electricity.
- Installed units are zero-rated for VAT until 31 March 2027, and the £2,500 air-to-air grant requires an existing fossil fuel or electric heating system to be replaced.
Heating with air conditioning cost UK: the per-kWh maths
We have used Ofgem’s price cap unit rates for 1 October to 31 December 2026: 26.32p per kWh for electricity and 7.97p per kWh for gas.
A unit’s efficiency is its SCOP, the kWh of heat delivered per kWh of electricity over a standard season.
Panasonic rates its Etherea 2.5 kW at 5.2 and its TZ 2.5 kW at 4.6, while Mitsubishi Electric rates the MSZ-HR 2.5 kW at 4.3.
A government impact assessment, using Energy Saving Trust field trials, assumed 84% efficiency for existing boilers and 90% for new ones.
| Heat source | Efficiency | Cost per kWh of heat | Cost of 1,000 kWh |
|---|---|---|---|
| Panel or fan heater | 100% | 26.3p | £263 |
| Gas boiler, new | 90% | 8.9p | £89 |
| Air con, Mitsubishi MSZ-HR | SCOP 4.3 | 6.1p | £61 |
| Air con, Panasonic TZ | SCOP 4.6 | 5.7p | £57 |
| Air con, Panasonic Etherea | SCOP 5.2 | 5.1p | £51 |
Our calculation, excluding standing charges. Gas heat cost is 7.97p divided by boiler efficiency.
Divide 26.32p by 8.86p, the cost of a kWh of heat from a 90% efficient boiler, and the break-even efficiency is about 2.97 (2.8 against an 84% efficient boiler).
SCOP comes from a standardised test, so treat it as a benchmark rather than a guarantee of real-world performance.
The best UK field evidence we found is for air-to-water heat pumps: Energy Systems Catapult’s trial of 742 heat pumps measured a median efficiency of 2.80, falling to 2.44 on the coldest days.
Those findings are not directly interchangeable with air-to-air systems, but they illustrate why real-world efficiency matters.
We therefore pay particular attention to the 3.0 break-even point, not just the 5.2 on the product specifications.
What will the January price cap do to heating with air conditioning?
Ofgem is due to announce the January to March 2027 energy price cap by 25 November 2026.
Cornwall Insight forecast £1,999 a year on 30 September, up 16% from the current £1,723.
The latest supplier forecasts reported by MoneySavingExpert on 15 October were:
- E.ON Next: £2,130
- EDF: £2,148
- British Gas: £2,185
Their average is £2,154, approximately 25% above the current cap.
These are forecasts, not confirmed prices.
No forecaster in our source comparison publishes final January unit rates, but Energyswitch reports that Cornwall splits its £1,999 forecast into approximately £959 for electricity and £1,040 for gas.
Against roughly £858 and £866 today, based on our arithmetic for 2,500 kWh of electricity and 9,500 kWh of gas annually, and assuming standing charges remain unchanged, that implies unit rates of approximately 30.4p for electricity and 9.8p for gas.
That would represent a gas price increase of around 23% and an electricity price increase of approximately 15%.
| Cost per kWh of heat | Now | January, Cornwall split (illustrative) | January, both rates up 25% (illustrative) |
|---|---|---|---|
| Electricity and gas unit rates | 26.32p and 7.97p | 30.4p and 9.8p | 32.9p and 10.0p |
| Gas boiler at 90% | 8.9p | 10.9p | 11.1p |
| Air con at SCOP 4.3 | 6.1p | 7.1p | 7.7p |
| Air con at SCOP 5.2 | 5.1p | 5.8p | 6.3p |
| Break-even efficiency | 3.0 | 2.8 | 3.0 |
Because Cornwall expects a larger percentage rise in gas prices, the case for heating with air conditioning strengthens in that scenario.
However, these figures are illustrations until Ofgem publishes the actual rates.
Our January 2027 energy price cap guide covers the forecasts and announcement timetable.
How much does heating with air conditioning cost per hour?
Panasonic’s figures for the Etherea 2.5 kW give 3.40 kW of heat from 0.70 kW of electricity at the rated operating point.
Its electricity input ranges from 0.16 kW to 1.18 kW.
At 26.32p per kWh, that means:
- Around 18p per hour at rated heating output.
- Around 31p per hour at maximum electricity input.
- Potentially less when the room is warm and the inverter reduces its output.
To put that into context, consider a room requiring 8 kWh of heat, equivalent to a 2 kW heating demand for four hours.
| Heating method | Cost to deliver 8 kWh of heat |
|---|---|
| Air conditioning at SCOP 5.2 | 40p |
| Gas boiler at 90% efficiency | 71p |
| Electric panel heater | £2.11 |
These figures assume the stated efficiencies and exclude standing charges.
A gas boiler cannot normally heat just one room without heating other parts of the system, so the practical saving may come from heating only the room you are using.
For example, using an air conditioner to warm a home office could avoid running the central heating throughout the house.
Our air conditioning running costs guide includes further annual examples.
Where heating with air conditioning wins
Air conditioning is particularly effective for heating individual rooms during milder weather.
Spring and autumn evenings
Spring and autumn are often the ideal times to use a reversible air conditioner for heating.
The outdoor air is relatively mild, which helps the heat pump operate efficiently.
An inverter unit can also reduce its electricity consumption as the room reaches the desired temperature.
For example, the Panasonic Etherea 2.5 kW can reduce its electricity input to 0.16 kW under suitable operating conditions.
Rather than heating the entire house with a gas boiler, you can warm the room you are occupying.
Homes currently using electric heaters
The potential savings are even greater when replacing direct electric heating.
A reversible air conditioner with a SCOP of 4.6 delivers heat for approximately 5.7p per kWh, compared with 26.3p from a panel or fan heater.
That represents a saving of approximately 78% per kWh of heat under the stated conditions.
This can make air-to-air heat pumps attractive for:
- Home offices
- Garden rooms
- Loft conversions
- Flats without gas
- Bedrooms requiring occasional heating
Our guide to how to heat your home cheaply explores other options.
Homes with solar panels
If you have solar panels, using an air conditioner for heating during daylight hours may reduce how much electricity you need to buy from the grid.
The benefit depends on how much solar electricity is available, the home’s heating demand and the value of any export tariff you would otherwise receive.
For more information, read our guide to using a heat pump with solar panels.
Where heating with air conditioning does not win
Although reversible air conditioners can be efficient heaters, they are not automatically the best choice for every property.
Deep winter and whole-house heating
Heating output and efficiency can fall as outdoor temperatures decrease.
For example, the Panasonic Etherea 2.5 kW delivers 3.40 kW of nominal heating output but approximately 2.80 kW at -7°C.
That is about 82% of its nominal output.
Its efficiency also decreases in colder conditions.
A system designed to provide primary heating must therefore be sized to meet the property’s heat demand on cold days, not simply selected using its nominal output.
For larger homes, multiple indoor units may be required.
Domestic hot water
Air-to-air heat pumps warm the air inside your rooms.
They do not normally provide domestic hot water.
If you currently use a gas boiler for hot water, you may need to keep it or install a separate hot water system.
Keeping the gas connection also means continuing to pay the gas standing charge.
At 29.68p per day, that is approximately £108 per year.
For a comparison of whole-home heating options, read our air source heat pump vs air conditioner guide.
Best heat pump air conditioner for heating
At 2.5 kW, several leading models have very similar heating efficiency ratings.
That means correct sizing and installation quality may matter more than the manufacturer’s name.
| Model, 2.5 kW class | SCOP | Heating limit or note |
|---|---|---|
| Mitsubishi Electric MSZ-LN25 | 5.20 | A+++ heating efficiency |
| Daikin Perfera 25 | 5.20 | Heating operation down to -20°C |
| Panasonic Etherea 2.5 kW | 5.20 | Heating operation down to -20°C |
| Panasonic TZ 2.5 kW | 4.60 | Heating operation down to -15°C |
| Mitsubishi Electric MSZ-HR25 | 4.30 | A+ heating efficiency; value range |
Sources: Mitsubishi Electric MSZ-LN, Daikin Perfera, and Panasonic’s Etherea and TZ technical specifications.
Which model should you choose?
For regular heating, a model with a higher SCOP may reduce electricity consumption.
The Daikin Perfera, Mitsubishi Electric MSZ-LN and Panasonic Etherea are all strong options at 2.5 kW.
If you primarily need occasional heating in a small room, a less expensive system such as the Panasonic TZ or Mitsubishi MSZ-HR may be sufficient.
The installer should assess the room’s heat loss, insulation and available wall space before recommending a capacity.
Our Daikin vs Mitsubishi Electric vs Panasonic comparison explores the differences in efficiency, noise, warranty and price.
What about installation cost, VAT and the grant?
The upfront installation cost is an important part of deciding whether heating with air conditioning makes financial sense.
According to AirConAdviser’s September 2026 pricing guide:
| Installation type | Typical fitted cost |
|---|---|
| Single-room split system | £1,500–£3,000 |
| Multi-split system | £3,500–£7,000 |
The final cost depends on the equipment, number of indoor units, pipework route, electrical requirements and outdoor unit location.
Our air conditioning installation cost guide explains these factors in more detail.
Is there VAT on air conditioning installation?
Under HMRC’s VAT Notice 708/6, qualifying installations of permanently fixed air source heat pumps are zero-rated for VAT until 31 March 2027.
The published rules provide for a reduced rate of 5% from 1 April 2027.
HMRC states that most fixed air conditioning units are air source heat pumps, although eligibility is assessed according to the circumstances.
Equipment purchased separately without qualifying installation generally attracts standard VAT.
Ask your installer to confirm the applicable VAT treatment before accepting a quotation.
Can you get a grant for air conditioning used as heating?
The Boiler Upgrade Scheme offers £2,500 towards eligible air-to-air heat pump installations in England and Wales.
However, the grant has important restrictions.
According to Ofgem’s guidance, the system must replace an existing fossil fuel or electric heating system and be designed to meet the whole property’s heating requirements.
Daikin’s guidance also explains that an eligible installation cannot operate alongside an existing fossil fuel heating system.
This means that installing a single air conditioning unit in a spare room while keeping your gas boiler would not normally qualify.
Confirm grant eligibility and installer accreditation before including the £2,500 in your budget.
FAQs
Is it cheaper to heat a room with air conditioning than with gas?
Yes, per kWh of heat, provided the air conditioner operates above an efficiency of approximately 3.
At October 2026 electricity and gas rates, a unit operating at SCOP 5.2 delivers heat for approximately 5.1p per kWh, compared with 8.9p from a 90% efficient gas boiler.
The practical saving can be greater when you heat only the room you are using rather than the whole house.
How much does it cost to run air conditioning on heat mode per hour?
A 2.5 kW Panasonic Etherea draws approximately 0.70 kW at its rated heating output.
At 26.32p per kWh, that costs about 18p per hour.
At its maximum electricity input of 1.18 kW, it costs approximately 31p per hour.
Once the room reaches the desired temperature, the inverter can reduce its output, so actual hourly consumption will vary.
Can air conditioning replace central heating?
Yes, but the system must be designed to meet the property’s heating needs.
For one or two rooms, a suitable reversible air conditioner can provide effective heating.
A whole home may require a multi-split system or several single-split units, sized for the coldest days.
You will also need a separate solution for domestic hot water because air-to-air heat pumps do not normally heat water.
Our guide to heating your home without gas explores the alternatives.
Do air conditioners still heat in freezing weather?
Yes, many modern reversible air conditioners can operate below freezing.
For example, Panasonic rates the Etherea to provide heating at outdoor temperatures down to -20°C.
However, its 2.5 kW model delivers approximately 2.80 kW at -7°C, compared with 3.40 kW nominally.
Heating capacity and efficiency can fall as temperatures decrease.
A system intended for primary heating should therefore be sized for the property’s winter heat demand.
Will the January 2027 price cap change the comparison?
Potentially in favour of air conditioning.
Cornwall Insight’s forecast implies gas prices could rise by approximately 23% and electricity prices by around 15%, based on our illustrative calculation.
If that happens, the efficiency needed for air conditioning to beat gas could fall from approximately 3.0 to 2.8.
However, these are forecasts.
Ofgem is due to announce the actual January 2027 cap by 25 November 2026, and the final unit rates may differ.
Our Verdict
Heating with air conditioning can be cheaper than gas, particularly when you only need to warm one or two rooms.
At October 2026 prices, a reversible split system operating at SCOP 4.6 delivers heat for approximately 5.7p per kWh, compared with 8.9p from a 90% efficient gas boiler.
That makes air conditioning especially attractive for home offices, bedrooms and living rooms during spring and autumn.
It is also substantially cheaper to run than direct electric heaters under comparable conditions.
However, we would not recommend relying on a small single-room unit to heat an entire property through winter without a proper heat-loss assessment.
Air-to-air systems also do not normally provide hot water, and installing one alongside an existing gas boiler would not ordinarily qualify for the £2,500 Boiler Upgrade Scheme grant.
Our recommendation is to choose a model with a strong SCOP, have it sized through a professional survey and compare the complete installation cost rather than the equipment price alone.
Qualifying installations currently benefit from 0% VAT until 31 March 2027.
Eco Happy can help you compare suitable air conditioning systems and obtain a survey-based quotation for your home.
Sources
- Ofgem – Energy Price Cap Unit Rates and Standing Charges
- Ofgem – October to December 2026 Energy Price Cap
- Cornwall Insight – January 2027 Price Cap Forecast
- Energyswitch – January 2027 Energy Price Cap Forecast
- MoneySavingExpert – Energy Price Cap Predictions
- Panasonic UK – Etherea Technical Specifications
- Panasonic UK – TZ Technical Specifications
- Mitsubishi Electric – MSZ-HR Product Information
- Mitsubishi Electric – MSZ-LN Product Information
- Daikin Europe – Perfera Technical Specifications
- UK Government – Improving Boiler Standards and Efficiency Impact Assessment
- Energy Systems Catapult – Heat Pump Field Trial
- AirConAdviser – Air-to-Air Heat Pump Costs
- HMRC – VAT on Energy-Saving Materials
- GOV.UK – Boiler Upgrade Scheme Grant Amounts
- Ofgem – Boiler Upgrade Scheme for Property Owners
- Daikin UK – Boiler Upgrade Scheme Guidance
- Daikin Central Europe – Air-to-Air Heat Pump Overview
