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Heat pumps are now the preferred choice as an alternative to gas boilers, being much more efficient in how they work. But what does efficiency actually mean when it comes to heat pumps?

A ground source heat pump can achieve efficiencies of 400 percent. This is because, unlike boilers, heat pumps produce more energy than they consume – particularly from electricity – and have no moving parts.


What Are Heat Pumps?

A heat pump is a device that moves heat from one place to another. The majority of heat pumps use electricity to do this, although there are some models that use other energy sources such as solar power or geothermal energy.

Air-to-air, water source, and geothermal heat pumps are three types of heat pumps connected by ducts. They gather heat from the air, water, or ground outside your home and concentrate it for use inside.

Related: Heat Pump Statistics

How Do Heat Pumps Work?

A heat pump extracts heat from the air outside of your house and transfers it to a refrigeration coolant, which is then compressed. Then the liquid coolant is transported back to the indoor unit where it’s heated again before being passed over the hot coolant for additional heating.

The compressor

The compressor is the component of the heat pump that compresses refrigerant vapor and circulates it throughout the system. In a hermetically sealed system, the compressor also acts as a pump, moving the refrigerant through the system.

The evaporator

The evaporator is located in the indoor unit of a heat pump and is responsible for extracting heat from the air passing over it. The heat extracted from the air warms the refrigerant passing through the coils of the evaporator.

The condenser

The condenser is located in the outdoor unit of a heat pump and its function is to reject heat gathered by the system from indoors. The refrigerant passing through the coils of the condenser is cooled and condensed back into a liquid form.

The expansion device

The expansion device is located between the evaporator and the compressor. Its purpose is to expand the refrigerant so that it can be easily drawn into the compressor.

Efficiency Of Heat Pumps

Are heat pumps efficient?

What makes heat pumps so efficient is that they move heat rather than generate it. Generating heat takes a lot of energy, especially if you’re using fossil fuels like natural gas or oil.

Heat pumps are also able to take advantage of the heat differential between indoors and outdoors. In winter, the air outside is colder than the air inside your home, so the heat pump can extract heat from the outdoor air and use it to warm your home. In summer, the reverse is true and the heat pump can extract heat from your home and use it to cool the outdoor air.

Coefficient of performance (COP) of heat pumps

In the case of a heat pump, its efficiency is defined as the ratio of useful heat energy generated to electrical energy consumed. A COP of 2.5 indicates that the heat pump provides 2.5 times as much heat energy to the system as it consumes in electricity.

For example, a heat pump with a COP of 3 produces 3 units of heat for every 1 unit of energy used. A heat pump with a COP of 4 produces 4 units of heat for every 1 unit of energy used. The higher the COP, the more efficient the heat pump is.

Heat pumps typically have a COP of between 2 and 4. This means that they produce 2 to 4 units of heat for every 1 unit of energy used. In comparison, gas boilers have a COP of between 0.8 and 1.2. This means that for every 1 unit of energy used, they only produce 0.8 to 1.2 units of heat.

So, if you’re looking for an efficient way to heat your home, a heat pump is a good choice. Thanks to their unique design, heat pumps can provide you with plenty of warmth during the winter months while also keeping you cool in the summer.

Efficiency Of Ground Source Heat Pumps

The Heat Pump absorbs and transmits three to four units of heat for each unit of electricity consumed. This means a Ground Source Heat Pump with good installation is potentially 300-400% efficient in terms of its electricity usage.

This makes the GSHP a very attractive renewable energy source for both domestic and commercial properties.

What Affects The Efficiency Of A Heat Pump?

There are a number of factors that can affect the efficiency of a heat pump, including:

  • The type of heat pump
  • The size of the heat pump
  • The climate
  • The insulation in your home

The type of heat pump you have will affect its efficiency. Air-source heat pumps are less efficient than ground-source heat pumps, for example.

This is because air-source heat pumps have to work harder to extract heat from the air, while ground-source heat pumps can take advantage of the earth’s constant temperature.

Heat pump efficiency vs temperature

When the outside temperature drops below -5°C, your heat pump’s performance may be reduced. The CoP for a typical heat pump should be about 4.5 when the outside temperature is approximately 7°C, but it can drop to 2.3 at -7°C.

This means that the heat pump will use more electricity to generate the same amount of heat, which will reduce its overall efficiency.

So, if you live in an area with cold winters, a ground-source heat pump may be a better option than an air-source heat pump.

Heat pump vs electric heat

Even though electric heating is much cheaper to install, heat pumps are a more efficient way to heat your home. This is because heat pumps only use a small amount of electricity to move heat from one place to another, while electric heating uses a lot of electricity to generate heat.

Air Source Heat Pump Running Costs

The Energy Saving Trust estimate that it costs about 4.65p per kWh to heat a home with gas, 4.82p per kWh for oil, 7.70p per kWh for LPG, and 20.06p per kWh for electric heaters. While a regular air-source heat pump may cost about 5.73p kWh to run, the efficiency of these systems is improved.

Heat Pump Regulations


  • The property boundary must be at least one metre from the air source heat pump’s exhaust vents.
  • Developments on pitched roofs are not allowed.
  • All components of the air source heat pump must be at least 1 m distant from the external edge of a flat roof.
  • Building requirements must be met if you have a ground source heat pump or an air source heat pump. It’s preferable to hire a professional who is MCS certified.


In terms of gross calorific values, the emission standards for NOx are technology and fuel-dependent and are measured in mg/kWh.

The following table summarizes the requirements and dates on which they will be implemented, as well as information regarding them.

Space heating or cooling energy efficiencyEmissions of nitrogen oxidesInformation requirements
TIER I01/01/201826/08/20181/1/2018
TIER II01/01/202101/01/2021
Warm air heatersusing fuel
Warm air heatersusing electricityN.A
Comfort chillerscombustion engine
Comfort chillerselectricN.A
Air-to-air air conditionerscombustion engine
Air-to-air air conditionerselectricN.A
Water/brine-to-air air conditionersN.AN.A
Fan coil unitsN.AN.A
Heat pumpscombustion engine
Heat pumpselectricN.A
High temperature process chillersN.A

Related: European Heat Pump Statistics


Beginning in 2023, all new residential central air-conditioning and air-source heat pump systems sold in the United States will be required to meet higher minimum energy efficiency requirements.

The new standards, which go into effect in 2023, call for a seasonal energy efficiency ratio (SEER)—a system’s cooling capability—of no less than 14 SEER in the northern part of the United States and 15 SEER in the southern portion of the United States, where cooling loads are a bigger percentage of home energy use. Higher SEER ratings indicate more energy-efficient equipment.

In addition, the new criteria call for improved heating efficiency in air-source heat pumps, measured by the equipment’s heating seasonal performance factor (HSPF). When compared to the previous requirement of 8.2 HSPF that went into effect in 2015, the minimum HSPF will be 8.8 HSPF under the new standard.

Ground Source Heat Pump Cost Calculator Uk


How much electricity does a heat pump use?

The average house consumes around 12,000-kilowatt hours (KWh) of heat each year. As a result, a CoP three heat pump would consume 4,000 kWh of electricity every year to meet this requirement. This amount is determined by the size of your home, how well insulated it is, and how much hot water you use.

Are Air Source Heat Pumps Expensive To Run?

An air-source heat pump can produce 3 kWh of heat for every 1 kWh of electricity consumed. The average yearly energy consumption in the UK is 12,000 kWh. It will cost you around £520 each year in heating expenses if your home consumes 4,000 kWh each year at a cost of £0.13 per unit.

At what temperature does a heat pump lose efficiency?

Heat pumps function most effectively when temperatures are at least 40 degrees Fahrenheit. When the temperature drops below 25-40 degrees Fahrenheit for most systems, they begin to lose efficiency. A heat pump works best when the temperature is greater than 40 degrees Celsius. When outdoor temperatures drop to 40°F, heat pumps begin losing efficacy and require more energy to perform their tasks.

What is better than a heat pump?

Boilers are more suited to delivering fast heat in older, less efficient structures. They may also be incorporated into systems that use them to deliver low-temperature heat in the same way as a heat pump — allowing them to work together with underfloor heating.

Does an air source heat pump run all the time?

No, your heat pump does not run all the time. However, if the temperature drops below 40 degrees, your heat pump is designed to operate almost constantly in order to keep your home comfortable. So don’t be concerned if the weather outside is extremely cold and your system is on all day.

Is an air source heat pump cheaper than gas?

Yes, an air source heat pump is less expensive to run than a gas boiler. The air source pump will save you money in the long term and you may get a significant proportion of the cost back through a grant, but the gas boiler is less expensive upfront.

How many kWh to heat a house?

In a mild climate, a typical home consumes between 5,000 and 30,000 kWh of energy each year for heating.

Do double radiators cost more to run?

Double panel radiators are by far the most efficient for standard and huge rooms. Single panel radiators radiate less heat since they have a smaller surface area for the heat to come from.

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