Can air conditioning heat your home?
By the A.C. Wilgar air conditioning team · Last updated October 2026
Quick answer: yes. Almost every modern split air conditioner is a reversible air-to-air heat pump. In heating mode a good unit delivers around 3 to 4.5 kWh of heat for every kWh of electricity it uses, which makes it three to four times more efficient than a plug-in electric heater and, at current energy prices, slightly cheaper per unit of heat than a typical gas boiler (see our cost assumptions below).
How air conditioning heats a room
An air conditioner moves heat rather than creating it. In summer it takes heat out of your room and releases it outside. In heating mode the refrigerant cycle runs in reverse: the outdoor unit draws heat from the outside air, even on cold days, and the indoor unit releases it into your room as warm air.
Because most of the energy comes from the outside air, rather than from the electricity itself, the system produces far more heat than the power it consumes. Many models keep heating effectively down to around -15°C outside.
How efficient is air conditioning for heating?
Heating efficiency is measured by the SCOP (seasonal coefficient of performance): the heat delivered over a typical heating season divided by the electricity used. A SCOP of 4 means 4 kWh of heat for every 1 kWh of electricity. You will find it on the unit’s energy label:
| Heating energy label | SCOP |
|---|---|
| A+++ | 5.1 or higher |
| A++ | 4.6 – 5.1 |
| A+ | 4.0 – 4.6 |
| A | 3.4 – 4.0 |
By comparison, a plug-in electric heater converts 1 kWh of electricity into 1 kWh of heat, and a modern gas boiler typically delivers around 0.9 kWh of heat per kWh of gas.
What it costs per unit of heat
Using the Ofgem price cap for October to December 2026 (electricity 26.32p per kWh, gas 7.97p per kWh, average direct debit rates), here is what each kWh of heat costs:
| Heating method | Efficiency | Cost per kWh of heat |
|---|---|---|
| Plug-in electric heater | 100% | 26.3p |
| Gas boiler | about 90% | 8.9p |
| Air conditioning, SCOP 3.5 | 350% | 7.5p |
| Air conditioning, SCOP 4.5 | 450% | 5.8p |
Running cost assumptions: the cost figures in this guide are illustrative estimates, not a quote or a guarantee of savings. They assume Ofgem price cap average direct debit unit rates for 1 October to 31 December 2026 (electricity 26.32p per kWh, gas 7.97p per kWh), exclude standing charges, and assume a gas boiler efficiency of 90% and air conditioning seasonal heating efficiency (SCOP) of 3.5 or 4.5. Your actual costs and any savings will depend on your energy tariff, the model installed, the size and insulation of the room, the weather, your settings and how you use the system.
For installation and cooling costs, see how much air conditioning costs to install and run.
Where heating with air conditioning works best
- Conservatories and garden rooms that are too hot in summer and too cold in winter.
- Loft conversions and extensions that the central heating struggles to reach.
- Home offices, so you can heat one room during the day without running the whole heating system.
- Spring and autumn, when you want to take the chill off without firing up the boiler.
- Bedrooms, where you can cool in summer and heat in winter from the same unit.
What air conditioning will not do
- It does not heat hot water. You still need a boiler, cylinder or other system for that.
- It heats with warm air rather than radiators, so it heats the room it is in. Heating a whole house would need an indoor unit in each room.
- In cold, damp weather the outdoor unit briefly pauses heating to defrost itself. This is normal.
- It works best in reasonably insulated rooms that are sized correctly. See what size air conditioner you need.
Air conditioning vs an air-to-water heat pump
| Air conditioning (air-to-air) | Air-to-water heat pump | |
|---|---|---|
| Heats | Rooms, with warm air | Radiators or underfloor heating |
| Cools | Yes | Usually no |
| Hot water | No | Yes, with a cylinder |
| Typical use | Individual rooms or zones | Whole-house heating |
| Disruption to install | Low: usually 1–4 days | Higher: can involve new radiators and a cylinder |
Many homes use both: a boiler or heat pump for whole-house heating and hot water, and air conditioning for the rooms that need cooling in summer and extra heat in winter.
Get expert advice for your home
We install air conditioning across Bromley, Beckenham, Orpington, Sevenoaks and the surrounding areas. Get an instant estimate online, or book a free home survey and one of our F-gas certified engineers will recommend the right system for your rooms.
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