How much electricity does a heat pump use? Energy consumption and costs explained

Heat pump power consumption – do heat pumps use a lot of electricity?

To calculate how much electricity a heat pump uses per day in the UK, we need to understand the average kWh of heat used per year and per day in an average household in the UK. For a home requiring 11,500kWh of heat per year (the UK average), or 32kWh of heat per day on average (including both hot water and heating), you should expect the heat pump to need 10kWh of electricity.  

Why? Well, this is because correctly installed air source heat pumps should be around 320% efficient or more – so for every 1kWh of electricity used, you’ll get 3.2kWh of useful heat from the system.  That’s likely to be around 3 – 4 times more efficient than a gas boiler.

Let’s take a quick look at how much electricity an air source heat pump would use in different sized houses. The table below provides some very approximate estimates (over the course of the year), per property size:

There are of course variations depending on several factors including flow temperature, system manufacturer, design, desired internal temperatures, and so forth, but this should give you a good idea. Of course, the bigger the home, the more electricity you will use, all other things being equal.  

How much does a heat pump cost to run?

For the heat pump to be cheaper than a gas boiler, two key factors come into play. Firstly, the efficiency of the two systems (the existing gas boiler and the heat pump replacement). Secondly, the difference in price between gas and electricity on a per kWh basis. Let’s look at an example.

• An 80% efficient gas boiler needs 12,500KWh of gas to provide 10,000kWh of useful heat. Let’s say the gas price is 7p/kWh, so it would cost you £875.00 per year

• A 320% efficient heat pump will need 3,125kWh of electricity each year to provide 10,000kWh of useful heat. If the electricity price is 22p/kWh, then that will cost £687.50. In this case the heat pump is cheaper to run

• But, in the case where gas is 6p/kWh and electricity is 25p/kWh, the two figures are £750 for gas, and £781.25 for the heat pump. This is because the heat pump efficiency can’t ‘make up for’ the difference in price on a kWh basis

This is called the ‘Spark Gap’ – the difference in price between electricity and the cost of fuel for heating. Oil and LPG are more expensive that natural gas, so the cost differential is better for heat pumps when replacing these. If you’re replacing direct electricity and don’t have an off-peak tariff (like Economy 7, to charge storage heaters at night for example), then your heating bill should drop by over two thirds.  

You should be aware that as of April 2025 the Government is looking at opportunities to reduce the Spark Gap in the future, which will make heat pumps much more competitive in terms of ongoing running costs, including against gas boilers.

Anything else I need to think about – and how can Thermly help me?

The energy used by a heat pump will depend on the efficiency of the heat pump and the heat demands of the property – the bigger the property, the more energy it will need (typically). Of course, if you improve the insulation of the property as well, the amount of energy needed will fall and you may be able to reduce the size and output of the heat pump, reducing your installation costs.  

Find out more today: contact our team on 0800 029 3129 or register for a call back: https://www.thermly.co.uk/contact  

• Read about the efficiency of heat pumps: https://thermly.co.uk/articles/article/how-efficient-are-heat-pumps  

• Find many of your questions answered here: https://www.thermly.co.uk/articles

‍

‍