Can I heat a flat with a heat pump or an air conditioner? Split units, the label, running costs and building rules

Usually yes. An air conditioner with a heating mode is a heat pump: in winter it moves heat from the outdoor air into your rooms. Called air-to-air heat pumps (mini splits in the US), they are often the simplest way to use a heat pump in a flat: no work on the radiators or the building’s central heating. They have two limits: they heat only the rooms that have an indoor unit, and they do not make hot water for the taps. In the example below, with Italian average prices for the first half of 2026, a unit with a seasonal efficiency of 4 heats a flat that needs 5,000 kWh of heat a year for about €390, against about €660 with a new gas boiler.

Is an air conditioner with a heating mode really a heat pump?

Yes. A heat pump works like a fridge run backwards: an electric compressor takes heat from the outdoor air, even cold air, and releases it indoors. The EU label rules for air conditioners, Delegated Regulation (EU) No 626/2011, cover devices that cool or heat indoor air, or both, and call one that does both “reversible”.

Not every air conditioner heats. Look at the label: a unit that heats shows a SCOP next to a red fan, a cooling-only unit only a SEER, its cooling efficiency over a summer, next to a blue one.

Air-to-air or air-to-water: which fits a flat?

	Air-to-air (split air conditioner)	Air-to-water
What it heats	The air in each room with an indoor unit	The water in your radiators or underfloor pipes
Hot water for the taps	No	Yes, if it is a model built for it (a “combination heater” on the label)
Work inside the flat	Indoor units on the walls, refrigerant pipes, a drain for condensation	Connection to the flat’s own heating circuit in place of the boiler
EU energy label	626/2011: SCOP printed, for up to three climates	811/2013: classes for water at 55 °C and 35 °C, no SCOP printed

Three ways to use a heat pump in a flat. A split air-to-air unit and a unit with no outdoor unit heat the room air and make no hot water for the taps; an air-to-water heat pump heats the water in the radiators, in place of the flat’s boiler. The labels differ: 626/2011 for the first two (a SCOP for a split, one COP at 7 °C for a unit with no outdoor unit), 811/2013 for air-to-water.

An air-to-water heat pump needs a flat with its own boiler and radiators that work with cooler water (how to check). In a building with central heating, the heating plant is a common part (Italian civil code, art. 1117). An owner may leave it only if this causes no significant imbalance or extra cost for the others, and still pays a share of its extraordinary maintenance, upkeep and safety upgrades (art. 1118). A split unit can simply run alongside the central heating.

How do you read the efficiency on the label?

SCOP, the seasonal coefficient of performance, is the heat a unit gives over a whole heating season divided by the electricity it uses: a SCOP of 4 means 4 kWh of heat for each kWh of electricity. The coefficient of performance, COP, is the same ratio at one moment. The label prints the SCOP for up to three climates: “Average”, always declared and calculated for a design day of −10 °C outside, “Warmer” (+2 °C) and “Colder” (−22 °C). It also gives the design load in kW, the heating need the unit is declared to cover on that design day, and the sound power of the indoor and outdoor units in dB(A), the usual unit for how much noise a machine makes.

Heating classes for the Average season run from A+++ (SCOP 5.10 or more) through A++ (4.60 to 5.10), A+ (4.00 to 4.60) and A (3.40 to 4.00) down to D. The ecodesign rules, Regulation (EU) No 206/2012, have required since 2014 a SCOP of at least 3.80 for units up to 12 kW using refrigerants with a GWP (global warming potential, how strongly a gas warms the climate compared with carbon dioxide) above 150, and limit the sound power of units up to 6 kW to 60 dB(A) indoors and 65 dB(A) outdoors.

Do not compare the SCOP with an air-to-water figure: the test rules differ.

What does it cost to run?

Assumption	Value	Source
Heat the flat needs in a year	5,000 kWh	Example value; change it to yours
SCOP of the air-to-air unit, Average season	4.0	Example value: the lower edge of class A+
Electricity	€0.3142 per kWh	Eurostat, Italy, January to June 2026, households using 2,500 to 4,999 kWh a year, all taxes included
Gas	€0.1137 per kWh	Eurostat, Italy, same period, band 20 to 199 GJ a year, all taxes included
Gas boiler seasonal efficiency	86%	Minimum for most new gas boilers since 26 September 2015 under Regulation (EU) No 813/2013

Both prices are Eurostat half-year averages, published in October 2026 and checked on 1 November 2026. They include VAT and other taxes, and also network charges and meter rental (electricity, gas), so the fixed parts of the bill are spread over each kWh.

Heat pump: 5,000 ÷ 4.0 = 1,250 kWh of electricity × €0.3142 = about €390 a year.
Gas boiler: 5,000 ÷ 0.86 = about 5,810 kWh of gas × €0.1137 = about €660 a year.
Break-even SCOP: €0.3142 ÷ (€0.1137 ÷ 0.86) = about 2.4.

How much it moves: with a SCOP of 3.0 (example value: new split units must show at least 3.80 on the label, but your own season can differ) the heat pump costs about €520; with electricity at €0.25, about €310; against an older boiler at 70% (example value), gas costs about €810. Your own heat need, from an Italian bill: gas for heating in Smc × 10.7 kWh (the conventional conversion ARERA uses) × your boiler’s efficiency. If you keep gas for hot water or cooking, the saving is smaller, because the gas contract stays. The heat pump vs gas boiler calculator works for an air conditioner too: enter its SCOP.

What about units with no outdoor unit?

Air conditioners sold “without an outdoor unit” sit wholly inside the room against an outside wall, drawing outdoor air through one duct and sending it back out through a second: two holes in the wall. Regulation 626/2011 calls them double duct air conditioners. Compared with a split unit:

A different efficiency figure. Their label gives a COP at one condition, 7 °C outside and 20 °C inside, not a SCOP for a whole season, so the two figures cannot be compared directly, and the letters use another scale: class A means a COP of 3.10 to 3.60 here, a SCOP of 3.40 to 4.00 for a split. The EU label rules call these units “inherently less efficient than split appliances”.
A lower legal minimum: a COP of 2.60 under Regulation 206/2012, against a SCOP of 3.80 for split units (both for refrigerants with a GWP above 150).
Noise in the room. The compressor is indoors, and the ecodesign rules allow these units a sound power of up to 65 dB(A) indoors, against 60 dB(A) for the indoor unit of a split up to 6 kW.

What rules apply in a block of flats?

Checked on 1 November 2026; rules can change.

Italy. The façade is a common part (art. 1117). Each owner may use common parts without changing their purpose or stopping the others from using them (art. 1102). Works in your flat must not damage common parts or harm the building’s stability, safety or “decoro architettonico”, its architectural appearance, and the administrator must be told beforehand (art. 1122); read the condominium’s regulation too. Under Legislative Decree 190/2024 (art. 7 and Annex A), heat pumps serving buildings need no building permit, as long as they comply with the town’s planning and building rules. On listed buildings, in protected natural areas and in protected landscapes a simplified authorisation procedure applies instead, and in some protected landscapes the landscape authority must approve the unit first. Neighbours can object to noise beyond “normale tollerabilità”, normal tolerance, judged case by case (art. 844).
England. Since 29 May 2025 the national permitted development right for air source heat pumps, which lets you install one without applying for planning permission, also covers units that heat and cool, such as air-to-air ones, as long as they are not used only for cooling (explanatory memorandum). On a block of flats it covers only one heat pump per building, with an outdoor unit of at most 0.6 cubic metres, and the installation must meet the MCS Planning Standards, which include a noise calculation. It does not cover listed buildings or a wall facing a road above the ground floor, and the limits are tighter in conservation areas.
France. An outdoor unit that changes the look of the building needs a déclaration préalable, a short planning declaration, at the town hall (service-public.gouv.fr, checked by its publisher on 30 March 2026) and, in a copropriété, a building owned in shares, a vote of the general assembly by absolute majority before work starts (service-public.gouv.fr).

Which incentives can you get?

Checked on 1 November 2026; incentives can change.

Italy, ecobonus. It covers heat pumps that replace the heating, fully or in part. An air conditioner added to a home that keeps heating with its gas boiler is not eligible, says ENEA’s FAQ 5D; the boiler may stay for hot water only if a qualified technician certifies that it can no longer easily be switched back to heating (FAQ 7D). The ENEA guide of 23 September 2026 gives 50% for the main home and 36% otherwise on spending in 2026 (36% and 30% in 2027), up to a deduction of €30,000 per home, with a form to ENEA within 90 days of finishing.
Italy, bonus casa. The renovation deduction lists “pompe di calore per climatizzazione degli ambienti” among energy-saving works (Agenzia delle Entrate guide, February 2026): 50% for an owner’s main home, 36% otherwise, on up to €96,000 per home, in 10 yearly instalments, with a form to ENEA within 90 days.
Italy, Conto Termico 3.0. A grant from the GSE, not a tax deduction, for heat pumps that replace existing heating; private households in homes can apply for this kind of work. It pays up to 65% of costs within caps worked out from the unit’s output and efficiency, in one payment up to €15,000. You apply on the GSE Portaltermico within 90 days of finishing, while the yearly budget lasts. The GSE heat pump catalogue for this work lists air-to-air models too, so a split system that replaces the old heating can qualify.
England and Wales. The Boiler Upgrade Scheme gives £2,500 towards an air-to-air heat pump to owners replacing fossil fuel or electric heating; an MCS-certified installer applies for you and the grant is taken off the price (how to apply).

The rest, country by country: home energy incentives by country.

Who installs it, and what should you ask?

Under the EU F-gas rules, Regulation (EU) 2024/573, people and companies who install or repair air conditioners and heat pumps containing fluorinated gases must be certified (art. 10), and equipment that is not hermetically sealed (its refrigerant pipes are joined on site, as in a split unit) may be sold to an end user only with evidence that a certified company will install it (art. 11). Italy’s national F-gas register, run by the chambers of commerce, lets you consult certifications. From 1 January 2029, new split air-to-air units up to 12 kW using gases with a GWP of 150 or more can no longer be placed on the EU market, save for safety reasons (Annex IV); fixed double duct units count as split. From 1 January 2035 the ban extends to new split units up to 12 kW using any fluorinated gas, again save for safety reasons. Units already installed can still be used and repaired.

Ask for:

The SCOP for your climate and each unit’s design load.
The outdoor unit’s position, sound power and condensation drain.
The installer’s F-gas certification and the refrigerant’s GWP.
For Italian incentives, the documents ENEA lists, such as the DM 37/08 declaration of conformity.
At least three written quotes.

This page explains how it works and what to ask; it is not financial advice or a design. Electrical work and paperwork are for a qualified installer or advisor.

Where to go next

Common questions

Is a mini split a heat pump?

Yes, if it has a heating mode. A mini split, or split air conditioner, that both cools and heats is an air-to-air heat pump: in winter it moves heat from the outdoor air into the room. The EU energy label tells you: a unit that heats shows a SCOP, its seasonal heating efficiency, while a cooling-only unit shows only the SEER, its seasonal cooling efficiency.

Is it cheaper to heat with an air conditioner than with a gas boiler?

It can be. With Italian average prices for January to June 2026 and a new gas boiler at 86% efficiency, a heat pump costs less to run once its SCOP is above about 2.4. In the example on this page, a unit with a SCOP of 4 heats a flat that needs 5,000 kWh of heat a year for about 390 euro, against about 660 euro with gas. The calculator redoes it with your figures.

Is there a heat pump without an outdoor unit?

Yes: air conditioners sold as having no outdoor unit sit entirely inside the room and use two ducts through the outside wall. EU rules call them double duct units. Their label gives one efficiency figure at 7 °C outside rather than a figure for the whole season, their legal minimum is lower than for split units, and the compressor runs inside the room.

Ecobonus or bonus casa for an air conditioner with a heat pump?

It depends on what the unit replaces. ENEA says the ecobonus does not cover a heat pump added to a home that keeps heating with its gas boiler; it covers heat pumps that replace the heating, fully or in part, and the old boiler may stay for hot water only if a technician certifies it can no longer easily heat the home. The bonus casa lists heat pumps for space heating among energy-saving works. In 2026 both give 50% on the main home of an owner and 36% in other cases (checked on 1 November 2026).

Do I need permission to put an air conditioner on the façade of a block of flats?

In Italy the façade is a common part of the building: each owner may use it as long as its purpose is not changed and the others can still use it. Works in your own flat must not harm the building's architectural appearance, the administrator must be told beforehand, and the condominium's regulation may add rules. In France an outdoor unit that changes the building's look needs a vote of the co-owners and a declaration at the town hall. In England one air source heat pump per block of flats needs no planning application, within size and siting limits.

Topics: heat pumps, air conditioning, flats, SCOP, air-to-air