How Much Does Air-Conditioning Cost to Run Per Hour?

Air conditioning is no longer seen as a luxury in the UK. With warmer summers and more people working from home, homeowners across Hampshire, Berkshire, Surrey, and Oxfordshire are investing in cooling and heating systems. One of the most common questions we hear is: how much does it cost to run an air-conditioning unit per hour?

The good news is that modern systems are highly efficient, and the running costs are often lower than people expect.

Typical Running Costs in the UK

The cost to run an air-conditioning unit depends on the size of the system, how it is used, and the current electricity tariff. As of 2025, the average UK electricity price is 28p per kWh (source: Ofgem).

Based on this, here are typical hourly running costs:

• Small bedroom unit (2.5 kW): 0.75 kWh per hour ≈ 21p per hour
• Medium bedroom unit (3.5 kW): 1.0 kWh per hour ≈ 28p per hour
• Large living room unit (5.0 kW): 1.2 kWh per hour ≈ 34p per hour
• Garden cabin unit (2.0 kW): 0.6 kWh per hour ≈ 17p per hour

These costs assume normal usage with the system running steadily, not constantly at maximum output.

Why Running Costs Are Lower Than Expected

Many homeowners are surprised by the affordability of AC use. This is because:

• Modern systems use inverter technology, adjusting power output to match the room’s needs rather than running flat out.
• Systems act as heat pumps, providing both cooling and heating with higher efficiency than electric heaters.
• Once the room reaches the set temperature, the system uses far less energy to maintain it.

This makes AC one of the most efficient ways to heat or cool a single room or a small set of rooms.

Local Examples

• A homeowner in Reading ran their 2.5 kW bedroom unit for 6 hours a day during summer. Total cost: around £38 per month.
• In Guildford, a 5.0 kW lounge unit cost around £1.50 per day when used for both heating in spring and cooling in summer.
• A garden office in Basingstoke used a 2.0 kW unit at £20 per month, cheaper than using a fan heater.

These figures show how practical AC has become in everyday life.

Factors That Affect Running Costs

Several things influence what you’ll pay:

• Set temperature: Lowering the thermostat more than necessary increases consumption.
• Insulation: Poor insulation means the system works harder.
• System size: An oversized unit uses more power, while an undersized one runs constantly.
• Usage patterns: Running AC continuously at maximum output is less efficient than steady, moderate use.

Comparing AC to Other Options

For heating, AC systems can be more efficient than traditional electric radiators. A 2.5 kW AC unit can provide the same heat output for less energy. For cooling, AC is far more effective than fans, which only circulate air rather than lowering the temperature.

Professional Guidance Ensures Best Results

Professional installation and correct system sizing are key to keeping running costs low. An experienced installer ensures:

• Units are matched to the size of each room
• Installation is compliant with F-Gas and Building Regulations
• The system runs efficiently and quietly

At ClimateWorks, we design and install systems that balance comfort with affordability. Across Hampshire, Surrey, Berkshire, and Oxfordshire, our customers are finding AC to be one of the most cost-effective upgrades to their homes.

References

• Ofgem – Domestic Electricity Prices
• Energy Saving Trust – Heating and Cooling Guidance
• UK Government – Building Regulations

Author Bio

Dr Julian Carter is Technical and Compliance Director at ClimateWorks. With more than 25 years of experience in air conditioning, refrigeration, and ventilation, he advises on energy efficiency, compliance, and system design. Julian has worked on projects across Hampshire, Berkshire, Surrey, and Oxfordshire, helping homeowners reduce running costs while improving comfort. As a visiting professor at a UK university, he teaches building services engineering and sustainable system design, combining academic expertise with real-world solutions.

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