Air Conditioning Electricity Usage, Explained in kWh

Typical draw by unit size

As a broad guide, a 2.5kW bedroom unit tends to average somewhere around 0.4–0.7kW in use, a 3.5kW living room unit around 0.6–1.0kW, and a 5.0kW unit serving a large open-plan space around 0.9–1.5kW. Those are averages across a session, not peak figures.

Every property is different. Solar gain, insulation, glazing and how often doors are opened all shift the numbers.

Turning that into daily and monthly figures

Multiply average draw by hours used to get kWh per day. A bedroom unit at 0.5kW for five hours is 2.5kWh — roughly the same as a couple of loads of washing.

Across a British summer, most households use air conditioning heavily for a handful of weeks, not continuously, which is why annual costs are usually modest.

The settings that move the number most

Set point is the biggest lever. Every degree lower in cooling costs more, and 23–24°C is comfortable for most people once humidity is under control. Fan speed on auto lets the unit find its efficient point rather than sitting at maximum.

Closing internal doors keeps the unit working on one room rather than trying to condition the hallway and stairs as well.

• Set 23–24°C in cooling rather than 18°C
• Use auto fan and let the inverter modulate
• Close doors, and blinds on sun-facing glass
• Clean the filters — a blocked filter costs real money

If you have solar panels

Cooling demand peaks when the sun is strongest, which is exactly when a solar array is generating. Households with PV often run cooling at close to no marginal cost through the middle of the day.

Pre-cooling the house on generation and coasting into the evening is a genuinely effective strategy.