comparison

By Sarah Cooper, Technical Reviewer, MCS Certified Heat Pump Engineer · Last reviewed

Air-Source vs Ground-Source Heat Pumps UK 2026: Which Is Bes

First published

TL;DR

  • Air-source heat pumps (ASHPs) cost £8,000-£15,000 installed, while ground-source (GSHPs) range from £18,000-£35,000, but both qualify for the £7,500 Boiler Upgrade Scheme grant.
  • GSHPs are 20-40% more efficient than ASHPs, especially in colder climates, but require garden space for trenches or boreholes.
  • ASHPs suit most UK homes, including urban properties, while GSHPs are ideal for rural homes with large gardens or high heat demand.
  • Running costs for both are typically 30-50% lower than gas boilers, but electricity prices and insulation quality heavily influence savings.
  • Use the home suitability check to assess your property before deciding.

In 2025, UK households installed over 100,000 heat pumps, a 30% increase from the previous year, according to OFGEM data. With the government’s target of 600,000 installations per year by 2028, more homeowners than ever are weighing their options. The most common dilemma? Choosing between an air-source heat pump (ASHP) and a ground-source heat pump (GSHP). Both technologies slash carbon emissions by up to 70% compared to gas boilers, but their costs, efficiency, and suitability vary dramatically.

This guide cuts through the noise. We’ll compare air-source vs ground-source heat pumps for UK homes in 2026, covering upfront costs, running costs, efficiency, installation requirements, and real-world performance. By the end, you’ll know which system fits your property, budget, and heating needs - and how to maximise grants like the £7,500 Boiler Upgrade Scheme.

Table of Contents

How Air-Source and Ground-Source Heat Pumps Work

Heat pumps don’t generate heat - they move it. Both air-source and ground-source systems use a refrigerant cycle to extract warmth from the environment and transfer it into your home. The key difference lies in their heat source.

Air-Source Heat Pumps (ASHPs)

ASHPs absorb heat from the outside air, even in temperatures as low as -15°C. They consist of an outdoor unit (similar to an air-conditioning unit) and an indoor unit that distributes heat via radiators or underfloor heating. Modern ASHPs are highly efficient, with seasonal performance factors (SPFs) of 3.0-4.0 in UK conditions. This means for every 1 kWh of electricity used, they produce 3-4 kWh of heat.

ASHPs are the most popular choice in the UK, accounting for 90% of heat pump installations in 2024, per Energy Saving Trust data. Their simplicity and lower upfront costs make them accessible for most homes, including flats and terraced houses.

Ground-Source Heat Pumps (GSHPs)

GSHPs extract heat from the ground, where temperatures remain stable at 10-13°C year-round. They use a network of pipes buried in trenches or boreholes to absorb this heat, which is then upgraded by the heat pump and distributed indoors. GSHPs achieve higher efficiencies, with SPFs of 4.0-5.0, but require significant outdoor space.

There are two main types of GSHP systems:

  1. Horizontal collectors: Pipes laid in trenches 1-2 metres deep, requiring a large garden (typically 2-3 times the floor area of your home).
  2. Vertical boreholes: Pipes drilled 50-150 metres deep, ideal for smaller gardens but more expensive.

GSHPs are less common in the UK, making up just 10% of installations, but they excel in rural properties with high heat demand or off-gas-grid homes.

Upfront Costs: ASHP vs GSHP in 2026

The biggest barrier to heat pump adoption is upfront cost. Here’s how ASHPs and GSHPs compare in 2026, including installation and grant impacts.

Cost FactorAir-Source Heat Pump (ASHP)Ground-Source Heat Pump (GSHP)
Unit cost£5,000-£10,000£10,000-£20,000
Installation cost£3,000-£5,000£8,000-£15,000 (trenches/boreholes)
Total installed cost£8,000-£15,000£18,000-£35,000
Boiler Upgrade Scheme£7,500£7,500
Net cost after grant£500-£7,500£10,500-£27,500

Source: air source heat pump cost guide and ground source heat pump cost guide, updated for 2026.

Why GSHPs Cost More

The higher price tag for GSHPs stems from groundwork. Horizontal systems require extensive trenching, while vertical boreholes need specialist drilling equipment. For example, a 3-bedroom semi-detached home might need:

  • ASHP: 1 outdoor unit + minor pipework (£10,000 total).
  • GSHP: 2 boreholes (£15,000) + heat pump unit (£12,000) = £27,000 total.

However, the £7,500 Boiler Upgrade Scheme grant applies to both systems, reducing the net cost significantly. For ASHPs, the grant can cover up to 90% of the total cost for smaller systems.

Hidden Costs to Consider

  • Upgrading radiators: Both systems work best with low-temperature heat emitters. If your home has old radiators, you may need to replace them (£2,000-£5,000).
  • Insulation: Heat pumps are less effective in poorly insulated homes. Loft or cavity wall insulation (£500-£2,000) may be necessary.
  • Planning permission: ASHPs rarely need permission, but GSHPs (especially boreholes) may require approval in conservation areas.

Running Costs and Efficiency: Which Saves You More?

Efficiency is where GSHPs shine, but running costs depend on electricity prices, heat demand, and system design. Here’s how the two compare.

Efficiency: SPF and Heat Output

  • ASHPs: SPF of 3.0-4.0 in UK climates. Performance drops in freezing temperatures, but modern units maintain efficiency down to -15°C.
  • GSHPs: SPF of 4.0-5.0. Ground temperatures are stable, so efficiency remains high year-round.

Example: A home with a 15,000 kWh annual heat demand would use:

  • ASHP (SPF 3.5): 4,286 kWh of electricity.
  • GSHP (SPF 4.5): 3,333 kWh of electricity.

Annual Running Costs

Using the OFGEM price cap for electricity (28p/kWh in 2026) and gas (7p/kWh), here’s a cost comparison for a 3-bedroom semi-detached home:

SystemAnnual Electricity Use (kWh)Annual Cost (£)Savings vs Gas Boiler (£)
Gas boiler15,000 (gas)£1,050-
ASHP (SPF 3.5)4,286£1,200-£150
GSHP (SPF 4.5)3,333£933£117

Assumptions: 15,000 kWh heat demand, gas at 7p/kWh, electricity at 28p/kWh. Source: running costs comparison.

Key Takeaways

  1. GSHPs are cheaper to run but have higher upfront costs. The payback period for the extra investment is typically 10-15 years.
  2. ASHPs can be more cost-effective for smaller homes or those with lower heat demand.
  3. Electricity prices matter: If electricity costs rise, the savings gap narrows. Conversely, if gas prices spike, heat pumps become even more attractive.

Installation Requirements: Space, Disruption, and Planning

Not all homes are equally suited to ASHPs or GSHPs. Here’s what you need to consider.

Air-Source Heat Pumps

  • Space: Requires an outdoor unit (about the size of a washing machine) with 1-2 metres of clearance. Can be wall-mounted or ground-mounted.
  • Disruption: Minimal. Installation takes 1-3 days and doesn’t require digging.
  • Planning: Permitted development in most cases, but restrictions apply in conservation areas or for listed buildings. Check with your local council.
  • Noise: Modern ASHPs are quiet (40-50 dB), but older models can be noisier. The MCS noise calculator helps assess compliance.

Ground-Source Heat Pumps

  • Space:
    • Horizontal systems: Need a garden 2-3 times the size of your home’s floor area. For a 100 m² home, you’d need 200-300 m² of garden.
    • Vertical boreholes: Require 1-2 boreholes (50-150 m deep) but take up less surface area.
  • Disruption: High. Trenching or drilling can take 1-2 weeks and may damage gardens or driveways.
  • Planning: Often requires permission, especially for boreholes. The Environment Agency regulates water source heat pumps.
  • Noise: GSHPs are quieter than ASHPs, as the ground absorbs most operational noise.

Which Is Easier to Install?

ASHPs win for simplicity. They’re suitable for:

  • Urban homes with small gardens.
  • Flats (with outdoor space for the unit).
  • Properties where minimal disruption is a priority.

GSHPs are better for:

  • Rural homes with large gardens.
  • Properties with high heat demand (e.g., older, poorly insulated homes).
  • Off-gas-grid homes where efficiency is critical.

Performance in UK Climates: Cold Snaps and Heat Demand

The UK’s unpredictable weather tests heat pump performance. Here’s how ASHPs and GSHPs handle different conditions.

Cold Weather Performance

  • ASHPs: Efficiency drops in freezing temperatures, but modern units (e.g., Mitsubishi or Daikin) can operate down to -25°C. In the UK’s mild winters, this is rarely an issue. However, during the 2022-2023 cold snap, some older ASHPs struggled to maintain output, leading to higher electricity use.
  • GSHPs: Ground temperatures remain stable, so performance is unaffected by air temperature. This makes them ideal for Scotland, Northern England, and Wales, where winters are colder.

Heat Demand and System Sizing

Both systems must be correctly sized for your home’s heat loss. Undersized units will struggle in cold weather, while oversized units waste energy.

  • ASHPs: Typically sized at 1.5-2 times the peak heat demand. For a 3-bedroom home, this might be a 10-12 kW unit.
  • GSHPs: Can be sized closer to the peak demand (1-1.5 times) due to their higher efficiency. A 3-bedroom home might need an 8-10 kW unit.

Illustrative composite based on typical UK installations: The Smiths, a family of four in Yorkshire, replaced their 25-year-old gas boiler with a 12 kW ASHP. During the 2022 cold snap, their system maintained indoor temperatures at 21°C but used 30% more electricity than usual. Meanwhile, their neighbours, the Johnsons, installed a GSHP with horizontal collectors. Their system’s performance remained steady, and their electricity use increased by just 10%.

Grants and Incentives: Maximising Your Savings

The UK government offers several schemes to reduce the cost of heat pumps. Here’s how to make the most of them.

Boiler Upgrade Scheme (BUS)

  • Grant amount: £7,500 for both ASHPs and GSHPs.
  • Eligibility: Must replace an existing fossil fuel system (gas, oil, or LPG). New builds are not eligible.
  • How to apply: Your MCS-certified installer handles the application. The grant is deducted from your invoice.
  • Deadline: The scheme runs until 2028, but funds are limited. Apply early to avoid disappointment.

Source: GOV.UK Boiler Upgrade Scheme.

Other Incentives

  1. 0% VAT: Heat pumps are VAT-exempt until 2027.
  2. Local council grants: Some councils offer additional funding. Check the Energy Saving Trust’s grant finder.
  3. Smart Export Guarantee (SEG): If you generate your own electricity (e.g., with solar panels), you can sell excess back to the grid.

Example Savings

For a £12,000 ASHP:

  • BUS grant: £7,500
  • VAT exemption: £2,400 (20% of £12,000)
  • Net cost: £2,100

For a £25,000 GSHP:

  • BUS grant: £7,500
  • VAT exemption: £5,000
  • Net cost: £12,500

Environmental Impact: Carbon Savings Compared

Heat pumps are a cornerstone of the UK’s net-zero strategy. Here’s how ASHPs and GSHPs compare in terms of carbon savings.

Carbon Emissions

  • Gas boiler: 2.2 tonnes CO₂/year for a 3-bedroom home (15,000 kWh heat demand).
  • ASHP: 0.9-1.2 tonnes CO₂/year (assuming UK grid electricity emissions of 0.233 kg CO₂/kWh in 2026).
  • GSHP: 0.7-0.9 tonnes CO₂/year (higher efficiency reduces electricity use).

Source: Energy Saving Trust.

Future-Proofing

The UK’s electricity grid is decarbonising rapidly. By 2035, the grid is expected to be 95% low-carbon, making heat pumps even greener. GSHPs, with their higher efficiency, will benefit the most from this shift.

Other Environmental Factors

  • Refrigerants: Both systems use refrigerants, but modern units use low-GWP (global warming potential) options like R-32 or R-290.
  • Ground disturbance: GSHPs require significant groundwork, which can disrupt local ecosystems. Horizontal systems are less invasive than boreholes.

Which Heat Pump Is Right for Your Home?

Choosing between an ASHP and a GSHP depends on your property, budget, and priorities. Here’s a quick decision guide:

FactorAir-Source Heat Pump (ASHP)Ground-Source Heat Pump (GSHP)
Upfront cost£500-£7,500 (after grant)£10,500-£27,500 (after grant)
Running cost£1,000-£1,500/year£800-£1,200/year
Efficiency3.0-4.0 SPF4.0-5.0 SPF
Space requiredSmall outdoor unitLarge garden or boreholes
Installation time1-3 days1-2 weeks
Best forUrban homes, small gardens, quick installationRural homes, large gardens, high heat demand

Step-by-Step Decision Process

  1. Check your home’s suitability: Use the home suitability check to assess insulation, heat demand, and space.
  2. Calculate costs: Use the savings calculator to compare upfront and running costs for your home.
  3. Get quotes: Contact MCS-certified installers for tailored advice. Aim for at least 3 quotes.
  4. Apply for grants: Ensure your installer is registered for the Boiler Upgrade Scheme.
  5. Plan for disruption: If opting for a GSHP, prepare for groundwork. For ASHPs, ensure outdoor space is clear.

FAQ

1. Can I install a heat pump in a flat?

Yes, but air-source heat pumps are the only viable option for most flats. You’ll need outdoor space for the unit (e.g., a balcony or roof) and permission from your freeholder or management company. Ground-source heat pumps are rarely feasible in flats due to space constraints. Check the heat pump vs gas boiler guide for more on flat installations.

2. How long do heat pumps last?

  • ASHPs: 15-20 years with proper maintenance.
  • GSHPs: 20-25 years, with ground loops lasting 50+ years. Regular servicing (every 2-3 years) is essential to maintain efficiency. The MCS installer directory lists certified professionals for maintenance.

3. Do heat pumps work with radiators?

Yes, but older radiators may need upgrading. Heat pumps work best with low-temperature systems (e.g., underfloor heating or large radiators). If your radiators are small or single-panel, you may need to replace them to ensure adequate heat output. Use the home suitability check to assess your current system.

4. What’s the payback period for a heat pump?

The payback period depends on your current heating system, energy prices, and grant eligibility:

  • ASHP vs gas boiler: 5-10 years (with £7,500 grant).
  • GSHP vs gas boiler: 10-15 years (due to higher upfront cost).
  • ASHP vs oil boiler: 3-7 years (oil is more expensive to run). Use the savings calculator for a personalised estimate.

5. Can I combine a heat pump with solar panels?

Yes, and it’s a great way to reduce running costs. Solar panels can provide the electricity needed to run your heat pump, cutting your bills by up to 70%. The Smart Export Guarantee also lets you sell excess electricity back to the grid.

Sources