Air Conditioning vs Electric Heating: Which Costs Less to Run?
If you're choosing between air conditioning and traditional electric heating for a room (a loft conversion, a garden office, an extension), the comparison is more one-sided than most people expect, but it's worth understanding why.
They're not really different fuel types
This is the part that surprises people: modern split air conditioning systems and electric panel heaters both run on electricity. The difference isn't the energy source. It's how efficiently that electricity is turned into heat.
How electric resistance heating works
A plug-in electric heater, panel heater, or storage heater generates heat through electrical resistance: essentially, electricity flowing through an element that gets hot. This is close to 100% efficient in the sense that almost all the electricity becomes heat, but 100% is actually the ceiling, not an achievement. You get roughly 1 unit of heat for 1 unit of electricity, no more.
How a heat pump (air conditioning) works
A split air conditioning system in heating mode works as a reversible heat pump. Rather than generating heat directly, it moves heat: extracting warmth from the outside air (yes, even when it's cold outside) and concentrating it indoors via the refrigeration cycle. Because it's moving heat rather than creating it from scratch, it can produce several units of heat output for every unit of electricity consumed. This efficiency ratio is typically referred to as the Coefficient of Performance (CoP), and well-specified systems commonly exceed 3, meaning three or more units of heat for every unit of electricity used.
What that means for running costs
In practical terms, heating a room with a heat pump-based air conditioning system can cost meaningfully less than heating the same room with a plug-in electric heater or storage heater, because you're getting multiple units of heat output per unit of electricity input rather than a roughly one-to-one exchange. The exact saving depends on the specific system's efficiency, the outside temperature, and how well insulated the room is. The underlying principle (moving heat vs generating it) is what drives the difference, not marketing claims.
Where electric heating still makes sense
Very occasional use. If a room is heated for an hour a week, the upfront cost of installing a split system may not be worth it compared to a cheap plug-in heater, even if the running cost per hour is higher.
No suitable outdoor unit location. Heat pump systems need an outdoor condenser unit; if there's genuinely nowhere sensible to put one (a mid-terrace flat with no external wall access, for example), electric heating remains the simpler option.
Very small or occasional-use spaces. For a small utility room or similar, the efficiency gains may not offset the installation cost within a reasonable timeframe.
Where air conditioning wins clearly
Rooms you heat regularly through winter and cool in summer (a home office, a loft conversion, a garden room used year-round) get the double benefit: efficient heating in winter, proper cooling in summer, from one system.
Larger or harder-to-heat rooms, where a plug-in heater would need to run for hours to make a dent, benefit most from the efficiency multiplier a heat pump provides.
The honest summary
If a room only needs occasional, light heating, a cheap electric heater is still a reasonable choice. But for any space you're heating regularly, especially one that also needs cooling in summer, a heat pump-based air conditioning system will typically cost less to run over a year, on top of solving the overheating problem a heater can't touch.
Want a proper comparison for your specific room? Get in touch for a free survey and we'll give you an honest recommendation, including if we think your usage pattern doesn't justify the investment.