If you’re thinking about getting a heat pump, you might have heard that they are more efficient than other types of heating such as boilers or electric storage heaters.

But what exactly does heat pump efficiency mean? And how might it affect your heat pump running costs?

What does efficiency mean?

The efficiency of an appliance is determined by how much of the energy it uses goes towards its intended purpose, rather than being wasted.

Modern gas boilers, for example, are required to be around 92% efficient. This means that 92% of the fuel they burn is used to provide heating and hot water, and around 8% is lost. So, for every £1 you spend on gas, at least 8p is wasted. What’s more, in-depth research finds that boilers rarely actually meet this 92% efficiency mark, and this figure also disregards the fact that gas boilers use some electricity to run.

How efficient are heat pumps?

Heat pumps capture renewable energy from the air using a small amount of electricity, and can generate almost four times as much energy as they use.

In some circumstances (ie when the weather is warm), heat pumps can be over 400% efficient. With our heat pump systems, we aim for a year round average efficiency of 340% – and our data shows that our installations achieve this.

Known as Seasonal Coefficient of Performance (SCOP), we calculate this average efficiency by taking into account the changes in outdoor temperature throughout the year.

Why are heat pumps so efficient?

Heat pumps can reach such a high level of efficiency because of the way the technology is designed.

They work by allowing heat energy from the air outside to transfer to a refrigerant gas inside the unit, which has an incredibly low boiling point of -52 degrees Celsius.

The refrigerant gas that has collected this heat energy then increases in pressure and temperature, and is passed through a compressor to raise its temperature even further. This heat energy is then transferred to water for use in your wet heating and hot water system.

The heat pump consumes electricity to run the above process, which enables it to efficiently transfer heat energy from the air outside into your home.

How can you make sure your heat pump is efficient?

At Good Energy, our heat pump experts will carefully design your heat pump system so that it can achieve a Seasonal Coefficient of Performance (SCOP) of 340%.

Our Head of Operations, Max Waddingham

Lots of different factors can impact how efficiently a heat pump can heat your home.

The good news is, most of the work to make sure your heat pump is efficient is down to us, the installer. We’ll check your EPC rating to see how well insulated your home is, and will recommend that any proposed insulation work is completed before you get a heat pump. You can still get a heat pump installed if your property isn’t as well insulated as it could be; and you no longer have to have completed all recomended items on your EPC in order to access the government’s £7500 heat pump grant. However, it will cost you more to heat an energy-inefficient home, just as it would with a gas or oil boiler.

Heat pump installation

During your home survey, we will explore what changes may need to be made to your existing heating system to be ready for a heat pump – for example you might benefit from having radiators with a larger surface area so they can emit more heat. This is to account for the fact that heat pumps heat water to a lower temperature than a gas boiler would.

We will also assess whether your current hot water cylinder will work effectively with your heat pump, or if you need one with a larger coil (again, because a larger surface area means more heat can be transferred).

Before you agree to installation, you’ll receive a detailed proposal showing the efficiency level your heat pump is likely to reach based on its design. This will give you a good idea of your expected running costs.

The final part of making sure your heat pump is working efficiently is down to using it efficiently. This technology is designed to provide a consistent level of warmth, rather than short blasts of heat. That means it’s more efficient to keep your home at a constant temperature – for example, setting your thermostat at 20 degrees during the day, and a few degrees lower overnight – rather than turning your heat pump off for long periods of time.

How much does a heat pump cost to run?

Although exact running costs will be down to the particularities of your house, electricity tariff and more, on average heat pump running costs are comparable to other types of heating. If you’re upgrading an older, less efficient boiler, then a heat pump could cost you substantially less in your monthly bills.

Here’s how heat pump running costs compare to different types of gas boiler:

Heat pump running costs compared with gas

Estimated annual heating costs of air source heat pumps and gas boilers for a medium-usage household with a heat demand of 12,000kWh. Running costs based on the following kWh prices (April 2024 price cap): £0.245 for electricity; £0.06 for gas with a £0.31 daily standing charge; heating efficiency of 70% for old gas boilers, 90% for modern gas boilers and 340% for heat pumps.

Find out more about how much a heat pump costs to run in this article.

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