What is a Heat Pump, and Will One Improve My EPC Rating

What is a Heat Pump?

A heat pump is a heating device that moves thermal energy from one place to another rather than generating heat by burning fuel. The most common type for residential use is the **air source heat pump (ASHP)**, which extracts heat from outdoor air, even at temperatures below freezing, and transfers it into your home via a refrigerant cycle.

**Ground source heat pumps (GSHP)** extract heat from the ground via buried loops of pipe, offering slightly higher efficiency in return for significantly higher installation costs and the need for suitable outdoor space.

Both types use electricity to power the compressor and pump, but they are considerably more efficient than electric resistance heaters: a well-specified heat pump can deliver three to four units of heat for every one unit of electrical energy consumed (Coefficient of Performance, or CoP).

How Heat Pumps Work in Practice

An air source heat pump unit is installed outside the property. It connects to the internal heating and hot water systems. Most residential heat pumps work best with **underfloor heating** or **larger radiators** because they produce heat at lower flow temperatures than a gas boiler (typically 35–55°C rather than 60–80°C).

If you are replacing a gas boiler with a heat pump in an existing property, you will likely need to either upgrade your radiators to larger models, accept that the system will run for longer periods at lower temperatures, or install underfloor heating as part of a broader renovation.

The Boiler Upgrade Scheme

The UK government's **Boiler Upgrade Scheme (BUS)** provides a grant to eligible homeowners in England and Wales to offset the cost of installing a heat pump. To access the scheme, you need a valid EPC with no outstanding loft or cavity wall insulation recommendations, and your installer must be MCS-registered and must apply for the grant on your behalf.

Will a Heat Pump Improve My EPC Rating?

The answer depends on the property. The Standard Assessment Procedure (SAP) used to calculate EPC ratings includes factors for the carbon intensity of the fuel used for heating. Under the current SAP 10.2 methodology:

• Gas has a relatively high carbon factor compared to electricity from the grid
• Electricity's carbon factor has been falling as renewable generation increases
• Heat pumps are credited for their high CoP efficiency

Practical Considerations

**Fabric First:** Insulate before upgrading the heating system. A heat pump in a poorly insulated property will be expensive to run and may not deliver the EPC improvement expected.

**Planning Permission:** Most air source heat pumps in England are installed under permitted development rights, meaning planning permission is not required provided certain conditions are met. Always check if your property is in a conservation area or is listed.

**MCS Certification:** Use MCS-certified contractors and ensure all commissioning documentation is retained, these are increasingly requested by solicitors and mortgage lenders in property transactions.

Property Passport UK makes it straightforward to locate a property's most recent EPC data alongside other records, so you can review what has been recommended before commissioning surveys or contacting installers.