How efficient are air source heat pumps?

Air source heat pumps are one of the most efficient heating for your home. Generating three times the amount of heat for every kw of energy used. Heat pumps are a sustainable, low carbon and help you save energy.  

By installing an Air Source Heat Pump – you can: 

• Increase Energy Efficiency by 300% (1) 

• Reduce Carbon Emissions by 80% (2) 

• Save £240 a year on energy bills (3) 

Unlike boilers that burn fuel to create energy (using 1kw of Gas to create 0.85kw of energy), air source heat pumps can produce 3kw of energy for every 1kw of electricity used – this is known as the Coefficient of Performance (CoP).  

So, if a heat pump has a CoP of 3.0, then it gives out three units of heat for every unit of electricity it uses. 

Gas boilers produce energy by burning fuel (a volume of gas is ignited, and a certain amount of energy is released). This means you can’t ever release more energy than is stored in that volume of gas. Meaning with a fuel burning system you can never achieve more than 100% efficient.  

For example: if you ignite some wood in a fire, you can’t get more energy than you have with that wood without adding more wood. You burn the fuel, you get heat, the fuel is gone, no more energy! 

On the other hand – Air source heat pumps don’t create heat. Air source heat pumps extract energy from the air to change the state of the refrigerant which is then compressed to produce heat. This useful heat is then transferred to the water that runs around the central heating system.  

Heat pumps are not a source of energy. Because they don’t have to burn a fuel, their efficiency depends on how well they’re able to move energy from one place to another.  

As technology improves, there’s no theoretical maximum to how efficiently you can move energy. Which means getting to be four, five, or ten times more effective at moving energy is simply an engineering problem – not a problem that breaks the laws of physics.

There are a few factors that affect heat pump efficiency (CoP), such as external temperature, the size of the property and how well your heat pump has been designed & installed. 

That’s why the design of an air source heat pump system is critical to ensuring the best possible performance.  

Systems that are designed correctly will dig into several factors and variables to ensure CoP is at a level where your heat pump can efficiency heat your home & provide hot water all year round.  

Heat pumps will keep you warm in winter, and provide the hot water you need, so there’s no disruption to your daily life.  

You may experience a drop in your CoP (efficiency) in temperatures below zero. Thankfully MCS requirements means all systems must efficiency be designed down to sub-zero temperatures. So, it’s only in locations and at times temperatures drop below this you will see efficiency impacted.  

In order to move that energy from one place, you have to use a certain amount of energy to power components like pumps, fans, and compressors. 

So when we talk about the energy used by an air source heat pump system, we’re talking about the energy required to operate it and actually extract the required heat from the air.  

For Example – If heat pumps use 1kW of electricity and produce 3kw of heat. A household that uses 12,000kw of gas a year, will only need to use 4,000kw of electricity to produce the same amount of heat – that’ a huge saving on energy & carbon.  

The average cost of an air source heat pump installation (including design, parts, and labour) is £6,100 – based on real installations, inclusive of government grants. 

A heat pump could cost you less than this or more, depending on a variety of factors, such as what type of house you live in, the number of occupants, insulation levels, and location. 

While installation costs may be higher than a gas boiler. Heat pumps have a much longer life span and have a much greater level of efficiency. 

Running costs for a heat pump also vary. Factors such as your energy tariff, type and size of system are a few of the variables which impact running costs. We explore more about costs in our dedicated costs page. 

Under current electricity prices (being higher than gas), A heat pump would be expected to cost a similar amount to run than the average gas boiler. If you’re replacing an older, G-rated gas boiler, you could even save around £240 a year on your energy bills (4). 

However, there is a way to save even more. Switching to a heat pump tariff (like the EDF Heat pump tariff) means you pay less for running your heat pump at certain times. Reducing the cost of your electric bill.  

With some clever scheduling of your hot water and smart meter, you can be money-savvy and save even more with your heat pump running costs.  

If you have solar panels then a heat pump may be the perfect choice. As the power (electricity) that is produced, can be used to also power your heat pumps, which means you can get reduce your energy bill even more. 

Much like any heating system, your energy consumption will be more in colder months, due to outside temperature and the heat loss profile of your home (the rate in which your property loses heat).  

A heat pump is similar to any other heating system in those colder months. As your home loses more heat, more heat is required to keep it warm.  

In winter you can expect your heat pump to use more energy and see an increase in your energy bill (depending on what kind of tariff you are on). The important thing to consider is that over the year, you would have still used 3x less energy than a boiler and saved some money too.  

Remember – Even if the savings on your energy bill are not enough to win you over, you are still reducing carbon and energy consumption, leaving a better world behind for future generations. Fitting your home with the latest technology can also increase it’s value. 

Of course, there are some quick ways you can ensure your heat pump remains as efficient as possible, which include:  

• Ensure TRVs (Thermostatic Radiator Valves) are set to their highest setting 

• Ensure weather compensation is set up correctly. 

• Leave your heat pump turned on all year round. 

• Ensure your hot water schedules are set up correctly 

• Keep windows closed on colder days (reducing heat loss) 

• Don’t alter the settings of your heat pump without first consulting an expert.  

• Look at dedicated energy tariffs which make running costs cheaper  

• Look into the benefits of solar panels to power your home & heat pump 

• Keep it clear from debris and obstruction, allowing for good air flow.  

We’ve been installing air source heat pumps for over 20 years now and know what happens when a system is poorly designed or installed. We’ve learned a  lot about heat pumps in these 2 decades. 

So, if you’re just starting to look into the options, or have a few questions. Save yourself some time. Give us a call or fill in a form.  

(1) (2) Annual heating demand of 25,000kWh; average heat pump SPF of 2.64; gas boiler efficiency of 84%; mains gas carbon emissions 0.21kg CO2e per kWh; electricity carbon emissions of 0.136kg CO2e per kWh; vehicle emissions of 225g CO2e per mile; average driving distance of 7,400 miles per year. https://energysavingtrust.org.uk/case-study/raj-and-his-familys-air-source-heat-pump/ 

 (3) Potential annual savings of installing a standard air source heat pump in a three bedroom semi-bedroom detached home, with radiator upgrades as required. https://energysavingtrust.org.uk/advice/air-source-heat-pumps/ 

 (4) Figures are based on fuel prices as of July 2024 (October 2023 for NI). Find out more about these calculations.  The running cost you can expect will depend on the size of your home, any heating system upgrade and any saving will also depend on the fuel type being replaced. You can expect the saving to range between old and new, depending on the age of your current heating system.