Air Source vs Ground Source Heat Pump — UK
Comparing ASHP and GSHP for UK homes — COP ratings, installation costs, space requirements, running costs and BUS grant eligibility.
Side-by-Side Comparison
| Property | Air Source (ASHP) | Ground Source (GSHP) |
|---|---|---|
| COP (seasonal average) | 2.8-3.5 | 3.5-4.5 |
| Installation cost | £8,000-14,000 | £15,000-25,000 |
| BUS grant (2026) | £7,500 | £7,500 |
| Net cost after grant | £500-6,500 | £7,500-17,500 |
| Running cost (3-bed semi) | £700-1,000/year | £500-800/year |
| Space required | ~1m x 1m outdoor unit | 200m² garden or borehole |
| Installation time | 2-3 days | 3-5 days (trenches) or 1-2 weeks (borehole) |
| Disruption | Minimal | Significant (garden excavation) |
| Noise | 40-55 dB at 1m | Silent externally |
| Lifespan | 15-20 years | 20-25 years (ground loop: 50+) |
Pros and Cons
Air Source Heat Pump
Pros
- + Much cheaper to install
- + No garden excavation needed
- + Quick installation (2-3 days)
- + Suits any property with outdoor space
- + Eligible for £7,500 BUS grant
Cons
- - Lower efficiency in cold weather
- - Outdoor unit produces noise
- - Performance drops below 0°C
- - Higher running costs than GSHP
- - Defrost cycles use energy
Ground Source Heat Pump
Pros
- + Highest efficiency (COP 3.5-4.5)
- + Consistent performance year-round
- + Silent operation (no outdoor unit)
- + Lower running costs
- + Ground loop lasts 50+ years
Cons
- - Much higher installation cost
- - Needs large garden or borehole
- - Significant installation disruption
- - Longer installation time
- - Longer payback period vs ASHP
UK Cost Comparison (2026 Prices)
For a typical 3-bedroom semi-detached house (10kW heat demand):
| Cost Element | ASHP | GSHP (borehole) |
|---|---|---|
| Heat pump unit | £3,500-5,500 | £5,000-8,000 |
| Ground loop / borehole | N/A | £5,000-10,000 |
| Hot water cylinder | £800-1,500 | £800-1,500 |
| Pipework, controls, commissioning | £2,500-4,000 | £3,000-4,500 |
| Total before grant | £8,000-12,000 | £15,000-24,000 |
| BUS grant | -£7,500 | -£7,500 |
| Net cost | £500-4,500 | £7,500-16,500 |
| Annual running cost | £700-1,000 | £500-800 |
When to Choose Each
Choose Air Source When
- Budget is limited
- Small or no garden
- Quick installation needed
- Retrofitting to existing property
- Most UK domestic situations
Choose Ground Source When
- Large garden available
- Maximum efficiency is the goal
- Noise is a concern (neighbours)
- New build (install during groundworks)
- Long-term investment property
Related Calculators
- Heat Pump Sizing Calculator — calculate the right heat pump output for your property
How We Calculate This
Frequently Asked Questions
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Last updated: April 2026
All calculations are estimates. Verify with your supplier.