Heat Pumps in the UK: Costs, Design & the BUS Grant (2026)

Heat pumps move heat rather than generating it directly, but seasonal performance and running cost depend on the complete design. The cost examples below are editorial planning ranges, not quotes. BUS is category-specific in England & Wales: standard air-to-water and ground-source categories are £7,500, with separate air-to-air, biomass and time-limited off-gas uplift categories. Confirm current funding on GOV.UK before planning finances. Start with measured heat demand, a room-by-room heat-loss calculation and whole-system quotes.

What is a Heat Pump?

A heat pump extracts heat from the outside air (ASHP) or ground (GSHP) and transfers it into your home. Think of it as a refrigerator in reverse—it moves heat rather than creating it.

How to read performance: A measured seasonal performance of 3.0 means 3 kWh of heat were delivered per 1 kWh of electricity. Use the proposed design value for planning, then compare it with monitored performance after installation.

Types of Heat Pumps

SCOP Explained

SCOP (Seasonal Coefficient of Performance) measures heat pump efficiency over a full heating season. It's the ratio of heat output to electricity input.

• SCOP 3.0: For every 1 kWh of electricity, you get 3 kWh of heat
• SCOP 3.5: For every 1 kWh of electricity, you get 3.5 kWh of heat
• SCOP 4.0+: For every 1 kWh of electricity, you get 4+ kWh of heat

Do not compare these ratios alone: the current system's measured fuel use, stated conversion efficiency, standing charges and the tariffs available to the property all affect cost.

Illustrative cost components—not quotes

Air Source Heat Pump (ASHP)

Ground Source Heat Pump (GSHP)

The Boiler Upgrade Scheme (BUS)

The UK government's Boiler Upgrade Scheme (BUS)may contribute toward eligible low-carbon heating installs in England & Wales (installer voucher). Amounts and rules change — confirm current funding on GOV.UK / Ofgem before planning finances. Eligibility is not assessed on this page and is not automatic:

• Air-to-water, ground-source and water-source: £7,500 standard categories
• Residential air-to-air: £2,500 category
• Eligible biomass boilers (rural, off-gas): £5,000 category
• Off-gas oil/LPG uplift (time-limited, not universal): Eligible off-gas oil/LPG properties may receive £9,000 for air-to-water or ground-source heat pumps (time-limited; confirm on GOV.UK).

BUS readiness checks (not an eligibility determination)

• Property must be in England or Wales (Scotland has separate schemes)
• Installer must be MCS certified
• The technology, existing heating system and property must meet the chosen category
• The owner must provide consent and identity evidence for a properly made application
• The installer should confirm the voucher category before work starts

Grant categories, budgets and scheme horizons can change. Confirm current funding and rules on GOV.UK / Ofgem and have the MCS-certified installer confirm a properly made application. Last reviewed 16 July 2026.

Running-cost outcomes: the honest take

Heat pump running costs depend heavily on your current heating system, insulation, and electricity tariff:

We do not publish a universal annual-saving figure because prices, heat demand and delivered SCOP change the answer. Ask each installer to show the calculation using the same measured baseline, tariff date and weather assumption.

When a heat pump is worth detailed comparison

These conditions can justify a full design and like-for-like financial comparison; none guarantees suitability or a saving:

• Replacing oil, LPG, or direct electric heating: Compare measured baseline and tariffs carefully
• Off-gas grid: No mains gas connection available
• Understood heat loss: defects resolved and emitters designed for the required flow temperature
• Underfloor heating or oversized radiators: Works with lower flow temperatures
• New build or major renovation: integrate fabric, emitters, hot water and electrical work early
• Solar and tariffs considered: model time-of-use and seasonal overlap rather than assuming a saving
• Carbon objective: compare the stated electricity, refrigerant and system boundary assumptions
• Long-term planning: include maintenance, finance, component life and tariff sensitivity consistently

Design constraints to resolve before deciding

These issues can change the scope, sequence or viability and need property-specific review:

• Fabric defects or high heat loss: resolve them with the heating design; sequence is property-specific, not a universal prerequisite
• Undersized emitters: design may require radiator, fan-convector or fabric changes
• Heritage or planning constraints: check consent, siting, noise and fabric limitations
• Outdoor-space constraints: survey unit location, clearances, condensate and neighbour impact
• Budget constraints: compare the full pre-grant scope, finance and contingency
• Short ownership horizon: compare in-life costs and objectives rather than assuming resale recovery

Heat Pump Installation Requirements

Insulation

Heat pumps work best when heat loss, emitters, hot water and controls are designed together. EPC Band C is not a universal prerequisite. Before installing, review:

• Fabric defects, insulation continuity, airtightness and ventilation
• Room-by-room design heat loss at the chosen conditions
• Emitter output at the proposed flow temperature
• Comfort, hot-water and occupancy requirements

Radiators and Flow Temperature

Heat-pump designs often use lower flow temperatures than existing boiler systems, but the selected temperature is property-specific. Emitters may need resizing or balancing to meet each room's calculated output. The same design principle applies to condensing boilers: lower flow can support efficiency where the emitters still maintain comfort—a step Nesta discussed during Guy Martin's House Without Bills retrofit alongside the heat pump install. See Nesta's project notes for how commissioning tied fabric, flow temperature, and monitoring together. If you are still on gas, try lowering boiler flow temperature before sizing a heat pump.

Hot Water Cylinder

Many whole-home heat-pump designs need stored hot water, but the cylinder type and volume depend on demand, recovery, space and the selected system. A combi-boiler home should include storage and pipework constraints in the design rather than assume a generic cylinder size.

Electrical Supply

Electrical demand depends on the selected unit, operating point, auxiliary heaters, controls and other loads. Ask the designer to confirm supply, consumer-unit, protective-device and circuit requirements in the itemised quote rather than assuming a generic allowance.

Finding MCS-Certified Installers

MCS (Microgeneration Certification Scheme) certification is required for BUS grant eligibility. To find installers:

1. MCS Certified Installer Database: mcscertified.com
2. Compare more than one quote: Use the same heat loss, scope and design conditions
3. Check evidence: Verify certification, references, insurance and complaints process
4. Ask about SCOP: Request the design assumptions and seasonal estimate
5. Warranty coverage: Compare provider, duration, exclusions, labour and transfer terms

Heat Pump Performance in Cold Weather

Common myth: "Heat pumps don't work in cold UK winters."
Reality: Product operating envelopes differ. A correctly selected unit can provide heat in sub-zero weather, but capacity, defrost and efficiency must be checked at the project design temperature.

Efficiency and available capacity generally change with outdoor and flow temperature. Ask the designer for performance at the design condition, not only a seasonal headline figure.

Carbon outcome

A correctly designed heat pump can reduce operational emissions relative to fossil heating, but the percentage is not universal. It depends on the previous fuel and efficiency, delivered SCOP, electricity carbon intensity, refrigerant and system boundary. Ask for the assumptions and keep commissioning data so the estimate can later be compared with measured use.

How to calculate a decision-specific payback

These examples use full install cost and do not auto-deduct BUS. Only apply a grant after eligibility is confirmed with your installer / GOV.UK.

Heat Pumps, EPC Ratings, and Real Bills

A heat-pump installation can change your EPC rating, but the direction and size depend on the certificate methodology, existing system and complete design. A modelled uplift does not automatically mean lower monthly direct debits when compared with a modern gas boiler on the tariffs available to the property.

Current Ofgem property-owner guidance recommends considering practical energy-efficiency work, but does not make outstanding EPC loft or cavity recommendations a universal prerequisite. Treat the EPC as a modelling view; use meter readings, heat-loss design and dated tariffs for financial planning. Sequence repairs, fabric, emitters, heating and controls as one design.

Stress-test future assumptions

Do not justify the project with one forecast. Recalculate the comparison when any of these inputs changes:

• Tariffs and standing charges: use the rates available to this property, not a national headline
• Measured heat demand: update the model after fabric or comfort changes
• System performance: compare the designed seasonal performance with monitored results
• Maintenance and finance: include service, replacement and borrowing assumptions consistently
• Policy and grants: re-check Ofgem and GOV.UK before treating support as available

Frequently Asked Questions

Next Steps

1. Check fabric: Resolve defects and understand heat loss; an EPC C is not a universal prerequisite
2. Get heat loss survey: Determine required heat pump size
3. Request MCS quotes: Compare more than one certified installer using the same scope
4. Discuss BUS eligibility with MCS installer: voucher process if rules are met — not guaranteed
5. Plan radiator upgrades: Budget for larger radiators if needed
6. Model solar and tariffs: compare seasonal overlap and export value; do not assume a saving