What Is a Heat Pump?
A heat pump is an electrically powered device that extracts heat from the outside environment — even when it's cold — and transfers it into your home. Think of it as a fridge running in reverse: instead of pumping heat out, it pumps heat in.
Heat pumps are extremely efficient because they move heat rather than generate it. For every 1 kWh of electricity used, a heat pump typically produces 3–4 kWh of heat.
Types of Heat Pumps
Air Source Heat Pumps (ASHP)
The most common type in the UK. An external unit (similar to an air conditioning unit) extracts heat from the outside air. They work efficiently down to temperatures as low as -15°C.
- Installation cost: £8,000–£14,000 (before grants)
- Space needed: External unit roughly 1m × 1m
- Best for: Most property types, especially those with good insulation
Ground Source Heat Pumps (GSHP)
Uses underground pipes (loops) buried in your garden to extract heat from the ground. More efficient than air source but requires significant garden space for installation.
- Installation cost: £15,000–£35,000 (before grants)
- Space needed: Significant garden area for ground loops
- Best for: Rural properties with large gardens
The Boiler Upgrade Scheme (BUS)
The UK government offers grants through the Boiler Upgrade Scheme to help with the cost of switching:
- £7,500 off an air source heat pump
- £7,500 off a ground source heat pump
This means an air source heat pump could cost as little as £500–£6,500 after the grant. The scheme is available in England and Wales for properties with a valid EPC.
Running Costs
Heat pumps use electricity, which is currently more expensive per unit than gas. However, because heat pumps are 3–4 times more efficient, the running costs are comparable or lower:
| System | Typical Annual Cost |
|---|---|
| Old gas boiler (60% efficiency) | £1,200–£1,500 |
| New gas boiler (92% efficiency) | £800–£1,000 |
| Air source heat pump | £700–£1,000 |
| Ground source heat pump | £500–£800 |
Is Your Home Suitable?
Heat pumps work best in well-insulated homes. Before installing one, you should ideally have:
- Good loft and wall insulation — this is essential
- Double or triple glazing
- Adequately sized radiators — heat pumps run at lower temperatures, so you may need larger radiators or underfloor heating
- Space for a hot water cylinder — most heat pumps need one
An EPC assessment will highlight whether your home's insulation is ready for a heat pump, and what improvements to make first.
Will a Heat Pump Improve My EPC?
Yes — significantly. Replacing a gas or oil boiler with a heat pump can boost your EPC rating by one to three bands. Combined with good insulation, many homes can reach Band B or even Band A.
The Bottom Line
Heat pumps are a proven, efficient technology that will only become more common as the UK moves away from fossil fuel heating. With government grants covering a large chunk of the cost, now is a good time to consider whether one is right for your home.
Start with an EPC to understand your home's current efficiency and what improvements make sense for you.
