Can air conditioning heat a house?

Yes: air conditioning that heats is a heat pump

An air conditioner doesn't make cold. It moves heat. In summer it takes heat out of your room and releases it outside. In heating mode the same refrigerant circuit runs in reverse: the outdoor unit draws heat out of the outside air, even on a cold day, and the indoor unit blows it into the room as warm air. This is why heating-capable systems are often called reverse-cycle air conditioning.

Planning law in England treats a heating-capable unit as an air source heat pump, and so does the Boiler Upgrade Scheme, which calls it an air-to-air heat pump. Every home system we fit heats as well as cools, so the question is less whether it can heat your house and more whether it's the right way to heat your house.

COP and SCOP in plain English

COP (coefficient of performance) is the heat a unit gives out divided by the electricity it uses, measured at one test condition. A COP of 4 means 4 kWh of heat for every 1 kWh of electricity. A plug-in electric heater has a COP of 1: every kWh of electricity becomes one kWh of heat, and no more.

SCOP is the seasonal version. It averages performance across a whole heating season, with mild days, cold days and the unit slowing down once the room is warm. It's printed on the energy label and it's the figure to compare. It uses an average European climate, so treat it as a fair guide rather than a promise for every week of winter.

Real heating figures from manufacturer data

Heating output and SCOP for popular bedroom and living room sizes, from the manufacturers' published data and their Eurovent certification records.

The size a unit is sold as is its cooling rating. In heating mode most units give out more than that. SCOP is for an average European climate.

Cost per kWh of heat: air con, gas and electric heaters

The fairest comparison is what each kWh of heat in the room costs you. We used the Ofgem price cap for 1 October to 31 December 2026: 26.32p per kWh of electricity and 7.97p per kWh of gas, the GB averages for Direct Debit.

Unit prices only. Standing charges are left out because you pay them whatever heats the room. Your region and tariff will differ slightly.

What an hour of heat costs

The same sums for putting 2 kW of heat into a room for an hour, about what a typical plug-in heater gives out on full.

Inverter units slow down once the room is warm, so a real hour often costs less than a full-output hour.

Is it cheaper to heat with air conditioning than gas?

Per kWh of heat, yes, at today's prices. Divide the electricity price by the gas cost per kWh of heat and you get the break-even point: 26.32p ÷ 8.9p is about 3. Whenever the unit is running at an efficiency above 3, it's cheaper than a 90% gas boiler. The models in the table above average 4.6 to 5.2 over a season.

It doesn't always win. Efficiency falls on the coldest days, so in a freezing week the gap narrows. If you keep gas for hot water or cooking, you keep paying the gas standing charge, 29.68p a day at the current cap. And energy prices move every three months, so the sums can change. Rerun them with the formula above if they do.

Where it wins clearly is against electric heating. Against plug-in heaters, panel heaters or an electric fire, air conditioning gives the same heat for about a fifth of the cost.

Room by room, or the whole house?

Most people start with one room: a cold loft, an extension the radiators don't reach, a home office used all day, or a bedroom that's too hot in summer and too cold in winter. One wall unit heats that room quickly and on its own thermostat, while the boiler carries on with the rest.

Heating a whole house is possible, but it's a design job, not one unit in the hallway. Warm air doesn't travel well through doors and up stairs, so each room you want heated needs its own indoor unit, usually several on one outdoor unit as a multi-split. We work out the heat loss of each room and size each unit for the coldest weather, not just the summer.

• Good fit: lofts, extensions, conservatories, garden rooms and home offices
• Good fit: flats with electric panel or storage heaters
• Good fit: rooms you want cooled in summer as well
• Needs care: whole-house heating, which needs a unit in every room you heat
• Not a fit on its own: homes that also need it to make hot water

Does it still heat when it's freezing outside?

Yes, within limits shown on the spec sheet. Panasonic lists its TZ range as heating with the outdoor temperature anywhere from -15 °C to 24 °C. Mitsubishi Electric's MSZ-LN25 is certified to keep heating down to -15 °C with its standard outdoor unit, and down to -25 °C with its Hyper Heating outdoor unit.

Output does drop as it gets colder. Panasonic's figures for the TZ25 show 3.3 kW of heat at its nominal rating and 2.7 kW at -7 °C outside. That's why we size for the coldest weather when you'll heat with it, not only for the summer.

In cold, damp weather the outdoor unit also defrosts itself every so often. The warm air pauses for a few minutes while it does, then carries on. That's normal, and not a fault.

The £2,500 Boiler Upgrade Scheme grant

Since 28 April 2026, the Boiler Upgrade Scheme in England and Wales has included £2,500 towards an air-to-air heat pump. In practice it can't be claimed yet. The grant needs an MCS-certified installer, and MCS said in April 2026 that installers can only apply once the certification bodies have UKAS accreditation, with no date given. Government statistics show 145 applications for the air-to-air grant by the end of August 2026 and no vouchers issued.

When it opens, it will be for homes only, it must replace your existing fossil fuel or electric heating, and the system must meet the whole home's heating demand, so one bedroom unit won't qualify. We'll never add the grant to a quote until it can really be claimed. Check mcscertified.com for the latest position.

Planning permission

On a house in England, a heating-capable unit can be permitted development under Class G, so you often don't need to apply. The outdoor unit must meet the size, position and noise rules, and since 29 May 2025 the unit must not be used solely for cooling. Our planning permission guide sets out every rule, and our planning checker looks up your postcode.

Prices for systems that heat and cool

Every home system on this list heats as well as cools. Prices include VAT. Multi-splits run several rooms from one outdoor unit.

• A bedroom or study

  2.5 kW wall unit, 5 m pipe, fitted in a day

  from£1,850inc. VAT

• A living room

  3.5 kW wall unit

  from£2,050inc. VAT

• Open plan or a loft

  5 kW wall unit

  from£2,450inc. VAT

• Two rooms, one outdoor unit

  Multi-split

  from£3,650inc. VAT

• Three rooms

  Multi-split

  from£5,100inc. VAT

• Four rooms

  Multi-split

  from£6,500inc. VAT

Heating with air conditioning: questions