Air Conditioning as Winter Heating: How Much an Air-to-Air Heat Pump Saves

A split air conditioner is in fact an air-to-air heat pump – and modern inverter models can reliably heat in winter, typically down to roughly −15 °C (premium cold-climate units are rated for operation as low as −25 °C). With a seasonal coefficient of performance (SCOP) of around 4 to 4.5, 1 kWh of heat costs roughly 0.9 to 1.1 CZK, about four times cheaper than direct electric heating, which on the D57d tariff uses roughly 4 CZK of electricity for the same kilowatt-hour. Air conditioning as winter heating is therefore an excellent supplementary and transitional solution for one or more rooms – but it is not a full replacement for an air-to-water system that heats the whole house, including hot water.

Air Conditioning and an Air-to-Air Heat Pump Are the Same Thing

The split air conditioner we install in flats and family homes is technically an air-to-air heat pump. The outdoor unit draws heat from the outside air, the compressor pumps it indoors, and the indoor unit releases it into the room. In summer the cycle runs in reverse and cools the room. The same machine therefore both cools and heats – you simply switch modes.

The fundamental difference compared with an air-to-water system lies in where the heat goes. Air conditioning heats the air in the room directly, where the indoor unit is mounted. An air-to-water system, by contrast, heats the heating water for radiators or underfloor heating and can also prepare domestic hot water for the whole house. That is why air conditioning is ideal for quickly heating a single room, but it will not distribute heat to the bathroom, the upstairs bedrooms, or the tap.

How Far Below Zero Air Conditioning Actually Heats

Common modern inverter air conditioners heat down to roughly −15 °C. Premium cold-climate models (Daikin, Mitsubishi, Toshiba, and others) are rated for operation as low as −25 °C. As the outdoor temperature drops, however, both the heating output and the efficiency gradually decline.

Efficiency is described by the coefficient of performance – the instantaneous COP and the seasonal SCOP. As a rough guide, the instantaneous COP falls as follows:

• around +7 °C: COP roughly 4–5 (1 kWh of electricity yields 4–5 kWh of heat),
• 0 °C: COP approximately 3–4,
• −5 °C: COP approximately 2.5–3.5,
• −10 °C: COP approximately 2–2.8,
• −15 °C: COP approximately 1.5–2.5.

So even at −15 °C, air conditioning delivers 1.5–2.5× more heat than the electricity it consumes – still far better than direct electric heating. The seasonal SCOP of quality units is usually 4.0 to 4.8, while premium models in energy class A+++ reach 5.1 and above. The difference between an SCOP of 3.5 and 5.0 means over a 30 % difference in consumption, so the specific model matters a great deal.

Defrosting – Why the Unit Sometimes Stops Heating

At low temperatures and high humidity, ice forms on the evaporator of the outdoor unit. The unit therefore automatically runs a short defrost cycle: for a few minutes it reverses operation, melts the frost, and then returns to heating. During defrosting the delivered heating output temporarily drops – this is normal behaviour, not a fault. In a colder and damper climate, defrosting kicks in more often, which slightly reduces the real seasonal efficiency.

How Much 1 kWh of Heat from Air Conditioning Costs

This is the main reason to heat with air conditioning at all. At a low-tariff price of around 4 CZK/kWh (the D57d tariff for heat pumps and electric heating) and an SCOP of around 4.5, 1 kWh of heat costs roughly 0.9 CZK. For comparison:

• Air conditioning (air-to-air), SCOP approx. 4.5: roughly 0.9 CZK/kWh of heat,
• Air-to-water heat pump, SCOP approx. 3.5: roughly 1.1–1.2 CZK/kWh of heat,
• Direct electric heating / electric boiler: roughly 4 CZK/kWh of heat (every kWh consumed = one kWh of heat),
• Natural gas (boiler approx. 90 %): roughly 1.6–3.2 CZK/kWh of heat depending on the gas price.

In running costs, then, air conditioning is roughly four times cheaper to run than direct electric heating and ranks among the cheapest electric heat sources to operate. Energy prices are variable, however, and differ by supplier and distribution area – in the Šumperk region and across the whole Olomouc Region, the distributor is EG.D, where the regulated component differs slightly from ČEZ. We therefore always recommend recalculating the specific saving against the current price list. A welcome change in 2026 is the abolition of the POZE levy (the Czech renewable-energy support fee), which has made running all electric heat sources cheaper by roughly 599 CZK for every MWh consumed.

When Air Conditioning as Winter Heating Pays Off – and When It Doesn't

In our experience, air conditioning as heating pays off mainly where it works as a supplementary or transitional source:

• heating one or more rooms – living room, attic, study, office,
• the transitional seasons in spring and autumn, when firing up the main boiler isn't worth it,
• properties where you want the air conditioning for cooling anyway – winter heating then comes practically as a bonus,
• quickly warming up a cold room, because warm air comes out of the unit within a few minutes.

Conversely, air conditioning is not a good choice as the sole heat source for a whole house:

• it does not heat domestic hot water or distribute heat to rooms without an indoor unit,
• in hard frosts below −15 °C, both output and efficiency drop significantly, so you need a backup source,
• warm-air heating can dry out the room air in winter and the heat is harder to retain than with radiant underfloor heating,
• the outdoor unit is a stationary noise source – at night the compressor must not exceed the noise limit at a neighbour's façade (40 dB at night, and with a correction for the tonal component effectively even less), so its placement needs careful thought.

The Šumperk Region and Mountain Climate – Why the Region Matters

The Šumperk and Zábřeh areas, and especially the foothills of the Jeseníky Mountains, have colder and longer winters than the lowlands. There are more days here when the temperature drops below −15 °C, and it is precisely on those days that air conditioning loses the most output. If you want to heat with air conditioning in winter in such a location, we recommend choosing a cold-climate model with rated operation deep below zero and allowing for backup heating during the harshest frosts.

For clients in Šumperk, Zábřeh, Mohelnice, Jeseník, Šternberk, Bludov, and the surrounding villages, we therefore recommend air conditioning for heating mainly as a smart supplement. If you want to heat your whole house economically and comfortably, including hot water, the right choice is an air-to-water heat pump, which we will design to match the building's heat loss.

What We Pay Attention to During Installation

For new residential air conditioners, we now use the refrigerant R-32 as standard (or R-454B), which complies with the European F-gas regulation in force in 2026; the older R-410A is no longer sold for new small split units. We carry out the installation with a valid F-gas handling certification, so you can be sure of safe and legal operation. We also plan the placement of the outdoor unit so that the compressor doesn't disturb the neighbours and so that water from defrosting can drain away freely.

Want Advice on Whether Heating with Air Conditioning Makes Sense for You?

Every house and every room is different – it depends on the insulation, the heat loss, the orientation, and how you want to heat for the rest of the year. As two specialists with more than ten years of experience in the field, we are happy to assess, with no obligation, whether air conditioning as supplementary heating will pay off for you, or whether an air-to-water heat pump makes more sense right away. Get in touch at +420 724 805 305 or by email at [email protected] and we'll arrange a no-obligation consultation at your home.