Heating with air conditioning: is it cheaper than gas?

Quick answer: Yes. Heating with air conditioning works if the unit is fixed and reversible, and it is far cheaper than electric panel heaters. Against a working gas boiler the saving is small. On Ofgem's rates for 1 October to 31 December 2026, a unit with a seasonal efficiency (SCOP) of 4.0 delivers heat at about 6.6p per kWh. A 90% efficient gas boiler delivers it at about 8.9p. Direct electric heating costs 26.3p. The break-even SCOP against gas is about 3.0, so if you already have a gas boiler that works, the fuel saving will not repay the installation.

Last checked 10 October 2026, against Ofgem, the Energy Saving Trust (EST), HMRC, the Boiler Upgrade Scheme rules, MCS, one Eurovent certificate and one Daikin data sheet. The arithmetic is ours. We found no measured study of air-to-air performance in UK homes, and we have not seen quotes for your home.

Can air conditioning heat a house?

Yes, if the unit is reversible and fixed to the wall. Cooling-only units do not heat.

The EST says air-to-air heat pumps are sometimes referred to as air conditioning, and that air conditioning can also be used for heating. HMRC's VAT guidance says its understanding is that most air conditioning units are air source heat pumps. Which? (17 July 2026) says that in theory there is little difference between the two.

It heats the rooms it serves. Whether that means the whole house depends on the number of indoor units, their size and how well the house holds heat.

How a reversible unit moves heat

The unit runs the cooling cycle backwards. The outdoor unit pulls heat from the outside air and the indoor unit releases it into the room. Nothing is burned, so one kWh of electricity can move several kWh of heat. The EST puts it at three to four units of heat per unit of electricity for heat pumps in general.

What it does not do

The EST's air-to-air page lists the limits: it does not usually heat water for taps and showers, it recirculates room air so you still need to ventilate, indoor units can be noisier than other heat pumps, and several indoor units normally need new pipework.

Check that the unit is reversible

Ask for the heating capacity in kW and the SCOP on the data sheet before you pay a deposit. Of the 39 Brighton and Hove installers on our list, 11 list air-to-air heat pump work on their own sites. Our guides to the air-to-air heat pump, the split system and air conditioning versus a heat pump cover the hardware.

How much does heating with air conditioning cost per kWh of heat?

Work in pence per kWh of heat, not pence per kWh of fuel. Gas and electricity are only comparable once you divide by efficiency.

The two Ofgem rates

Ofgem's price cap for 1 October to 31 December 2026, Direct Debit, Great Britain average: electricity is 26.32p per kWh and gas is 7.97p per kWh. Ofgem's summary notes that VAT on electricity bills is cut from 5% to zero from 1 October 2026 to 31 March 2027, while gas stays at 5%. We leave standing charges out of the table and return to them below.

Turning a rate into the price of heat

Divide the fuel price by the efficiency. The EST says an A-rated boiler should convert 90% of its fuel into usable heat. For a heat pump, use the seasonal figure: a SCOP of 4.0 means four units of heat for each unit of electricity over a heating season. COP is the same ratio at one test point, so ask for the SCOP, not the best COP in the brochure.

Rates: Ofgem, 1 October to 31 December 2026. Boiler efficiency: EST, updated 16 July 2026. The 80% row is our assumption for an old boiler. The arithmetic is ours.

Why the maker's number is not your bill

A certificate figure comes from a laboratory test of one unit. It does not include your insulation, your thermostat habits or a cold snap in February. The EST says there is currently "not much data on how air-to-air systems perform in the UK", so it is hard to know how much you would save. We treat a SCOP of 5 as a best case. Our running costs guide and running costs calculator let you test your own rate.

Is air conditioning cheaper than gas heating?

Per kWh of heat, yes above a SCOP of about 3.0, by a small margin at typical figures.

The break-even SCOP

Divide the electricity rate by the price of gas heat: 26.32 / 8.86 = 2.97. Above a SCOP of about 3.0, the air conditioner is cheaper to run than a 90% gas boiler. Against an 80% boiler the break-even is 2.64. Below those numbers, gas wins on fuel cost.

Case A: replacing electric panel heaters

Assume a room or flat needs 3,000 kWh of heat a year. That figure is ours, not sourced. Change it to match your own use.

• Panel heaters: 3,000 x 26.32p = £789.60 a year.
• Air conditioning at SCOP 4.0: 3,000 x 6.58p = £197.40 a year.
• Difference: about £592 a year.

The EST's typical cost for one room is about £1,900. At about £592 a year, that repays in a little over three years on heating alone, before any cooling. This is the strongest case for heating with air conditioning.

Case B: a house with a working gas boiler

Same 3,000 kWh of heat. Gas at 90% costs about £266 a year. Air conditioning at SCOP 4.0 costs £197.40, a saving of about £68. At SCOP 3.0 it costs £263.10, a saving of under £3.

The EST makes the general point for heat pumps: with a newer gas or oil boiler they will not necessarily be cheaper to run, because electricity costs more per unit. Against £1,900 or more installed, the gas comparison alone never pays back. With a working boiler, the case for air conditioning is cooling, plus heat for a room with no radiator.

Case C: a room or home with no heating, or no gas

Compare the unit with the heater you would otherwise buy. Against a plug-in electric heater, the Case A sums apply. See our guides to air conditioning in flats and air conditioning for a bedroom.

Standing charge and an hourly check

The gas standing charge is 29.68p a day, £108.33 over a year. You save it only if you remove gas entirely.

Daikin's Perfera data sheet lists the 35 size at 4.00 kW of heat for 0.99 kW of electricity, at 7°C outside. At 26.32p that is about 26p an hour, or about £1.04 for four hours. A full day at that rating would be about £6.25. Inverter units slow down once the room is warm, so real use is usually lower, though a unit pushed harder in cold weather can draw more.

Does it work in a cold UK winter?

It works, and efficiency falls as it gets colder. The certificate for one unit gives numbers.

What the certificate says at -10°C

Eurovent Certita certifies Daikin's RXM35A and FTXM35A pairing. The certificate lists a COP of 4.55 at the standard 4.00 kW of heat. At -10°C the COP is 3.15, with an output of 2.50 kW. The seasonal figure is a SCOP of 5.20. Daikin's Perfera data sheet gives a heating operating range of -20 to 24°C or -15 to 24°C, depending on the outdoor model.

At 26.32p, a COP of 3.15 works out at about 8.4p per kWh of heat, still a little under gas at 90%. That is our arithmetic on one certified point.

Three limits. It is one unit, from an older generation than the current Perfera. The figures come from a laboratory. And the certificate does not label the climate zone for the SCOP, so we do not read it as an average UK winter. At -10°C the unit also gives out less heat, so a larger unit or a second heat source may be needed.

Run it steadily

The same certificate lists part-load results. At 0.95 kW of output the COP is 6.48, against 4.55 at the full 4.00 kW; under the EN 14825 test standard both of those points sit at 7°C outside. That suggests low, steady output is the efficient way to run a unit. We found no independent UK study confirming it, so treat it as a pointer from one certificate, not a rule.

When heating with air conditioning makes sense, and when it does not

It suits a small, well-insulated home or a flat, with a unit in each room you use. The EST notes that air-to-air systems are more often installed in smaller properties.

A single indoor unit heats one open space, not the house. Several indoor units mean a multi-split system, which the EST says normally needs new pipework. Our multi-split page for Brighton and Hove explains the layout. Outdoor units can need planning permission, so read our planning guide for Brighton and Hove and check with the council.

What it costs to put in

The EST gives a typical cost of about £1,900 for one room and around £3,700 for a three-bed semi, without showing a method or date. Published single-split ranges we read: Trade2Base £1,800 to £3,500 (1 July 2026), Heatable £2,000 to £3,500 (7 October 2026) and Airtasker £1,500 to £3,000 (25 August 2026). For a three-room multi-split, Trade2Base gives £4,500 to £7,500.

Only 7 of the 39 installers on our list publish any price, so you will need quotes. Our installation cost guide and cost calculator set out the ranges.

Grants and VAT: what you can and cannot claim today

Boiler Upgrade Scheme: £2,500 on paper

Ofgem's installer guidance, in force from 28 April 2026, lists £2,500 for air-to-air heat pumps in residential properties. The scheme requires an MCS-certified installer. On 10 October 2026, MCS said no installers were yet certified to install air-to-air heat pumps, and the EST (updated 11 September 2026) said grants for them were not available yet. So the £2,500 could not be claimed on the date we checked.

The rules also require the heat pump to fully replace the old fossil fuel or non-heat-pump electric system. A heat pump installed alongside a gas or oil boiler is ineligible. Seven of the 39 installers on our list claim MCS certification in their own words; given MCS's statement, those claims most likely relate to other heat pump work. Our air-to-air heat pump grant guide tracks the position.

VAT on installation: 0% to 31 March 2027, then 5%

HMRC's Notice 708/6 says a zero rate applies to installing certain specified energy-saving materials from 1 May 2023 to 31 March 2027, reverting to 5% from 1 April 2027. In cases of doubt, whether a given air conditioning unit counts depends on the facts of each case. Installers on our list disagree: some quote 5%, others 0%. This is general information, not tax advice. Ask for the VAT rate and any grant claim to be written into the quote.

What moves the numbers after today

• Electricity VAT returns. If 5% VAT is added back to the 26.32p rate after 31 March 2027, it becomes 27.64p. The break-even SCOP against a 90% boiler rises to about 3.12, and SCOP 4.0 heat costs 6.91p. That is our arithmetic, not a forecast.
• The cap resets. Ofgem sets the cap every three months; the next periods start on 1 January and 1 April 2027. Ofgem will announce the January rates by 25 November 2026.
• Standing charges. They change with the cap, and you only save the gas one by removing gas.
• Tariff. The EST says a heat pump time-of-use tariff should cut running costs. We have not checked individual suppliers' tariffs.

What to ask before you buy

1. Ask for the heating capacity at low outdoor temperatures and the SCOP, from the data sheet.
2. Ask for a running-cost estimate for your home, with its assumptions.
3. Ask for the installer's F gas certificate and check the register. Our F gas guide shows how.
4. Ask for the VAT treatment and any grant claim in writing on the quote.
5. Get three itemised quotes for the same specification, with noise levels and the position of the outdoor unit.

Our Brighton and Hove air conditioning installers pages show what we found for each firm, including where we found nothing. A separate list covers heat pump installers in Brighton and Hove. We take no money to list or rank anyone.

our Brighton and Hove installer directory