How to Improve
EPC Rating
EPC ratings improve through specific upgrades scored under the SAP methodology. Loft insulation is the cheapest single improvement. New heating systems plus solar panels deliver the biggest jumps. The right order saves thousands of pounds plus delivers more rating points per pound spent.
EPC ratings improve through specific upgrades that score under the Standard Assessment Procedure (SAP) methodology. The most cost-effective improvements in 2026 are loft insulation (£300 to £1,000 for 5 to 15 SAP points), cavity wall insulation (£500 to £1,500 for 5 to 12 points), efficient lighting throughout (£50 to £300 for 1 to 3 points) plus modern heating controls (£150 to £500 for 1 to 3 points). Larger upgrades include A-rated condensing boilers (£2,000 to £4,000 for 3 to 8 points), solar PV panels (£5,000 to £10,000 for 8 to 20 points), heat pumps (£7,500 to £13,000 for 5 to 15 points) plus solid wall insulation (£8,000 to £20,000 for 10 to 25 points). Total typical UK upgrade cost from D to C is £6,800 average per property based on 2025 data.
The figures that matter
Underlying metric
Standard Assessment Procedure scores 1 to 100+. Improvements add SAP points which lift the EPC band.
Loft insulation
Single biggest cost-effective improvement. Often £300 to £1,000.
Solar PV
Largest single jump from a single improvement. £5,000 to £10,000.
UK avg
Government data for typical upgrade cost to lift a property from D to C in 2025.
Four things to consider
Insulation first
Cheapest per SAP point. Loft, cavity walls plus floor insulation give the best return on investment.
Heating system second
Modern A-rated boilers, smart controls plus efficient zone control add SAP points cost-effectively.
Glazing only on poor properties
Replacing single glazing with double-glazing helps. Replacing existing double with triple rarely pays back.
Renewables for the biggest jumps
Solar PV plus heat pumps deliver large rating jumps at higher upfront cost. Best for D to B journeys.
Order of upgrades for best EPC return
Improving an EPC means adding SAP score points. Each upgrade is scored against the SAP methodology used for existing homes (Reduced Data SAP or RdSAP). Some upgrades give many points cheaply. Others give fewer points expensively. The right order maximises rating per pound spent.
Tier 1: Cheapest improvements with biggest per-pound impact.
- Loft insulation to 270mm. £300 to £1,000. Adds 5 to 15 SAP points. Should be every UK home's first move if not already done.
- Cavity wall insulation. £500 to £1,500. Adds 5 to 12 points. Suitable for most UK homes built 1920 to 1990 with cavity walls.
- LED lighting throughout. £50 to £300. Adds 1 to 3 points. Trivial install with immediate energy bill savings.
- Hot water cylinder insulation. £30 to £80. Adds 1 to 2 points. Cheapest single improvement available.
- Draught-proofing. £100 to £300. Adds 1 to 2 points. Small SAP impact with noticeable comfort improvement.
Tier 2: Moderate cost with solid returns.
- Modern A-rated condensing boiler. £2,000 to £4,000 fitted. Adds 3 to 8 points if replacing pre-2005 non-condensing. Smaller jump if replacing newer boilers.
- Modern heating controls plus thermostat. £150 to £500. Adds 1 to 3 points. Smart thermostats with zone control score better than basic thermostats.
- Underfloor insulation. £500 to £2,000. Adds 2 to 6 points. Best in homes with suspended timber floors plus accessible voids.
- Double glazing in single-glazed properties. £5,000 to £12,000 for whole house. Adds 4 to 8 points. Replacing existing double-glazing rarely worthwhile for SAP gains.
Tier 3: Higher cost with bigger jumps (best for D to B).
- Solar PV panels (4kW system). £5,000 to £10,000 fitted. Adds 8 to 20 points. Largest single SAP boost commonly available. Also generates electricity reducing bills.
- Air source heat pump (replacing gas boiler). £7,500 to £13,000 with grant. Adds 5 to 15 points. Boiler Upgrade Scheme grant up to £7,500 reduces net cost.
- Internal solid wall insulation. £8,000 to £15,000. Adds 10 to 20 points. For solid-wall Victorian plus Edwardian homes which cannot have cavity wall insulation.
- External solid wall insulation. £12,000 to £25,000. Adds 12 to 25 points. Higher impact than internal but visible plus not suitable for many properties.
Typical SAP scores by EPC band:
- A: 92+
- B: 81 to 91
- C: 69 to 80
- D: 55 to 68
- E: 39 to 54
- F: 21 to 38
- G: 1 to 20
Important plus practical tips:
- Get a fresh EPC after improvements. Existing EPCs do not auto-update. Cost £60 to £150.
- Keep installation certificates plus invoices. The new assessor needs evidence of insulation, boiler plus solar installs.
- Apply for relevant grants. Boiler Upgrade Scheme (£7,500 for heat pumps), ECO4 plus Great British Insulation Scheme can reduce costs significantly.
- Plan in the right order. Insulate before installing a heat pump. A smaller heat pump suits a better-insulated home.
- Check Warm Homes Plan support. The 2026 Warm Homes Plan introduced £5 billion of additional support for energy upgrades.
Real number ranges
EPC improvement cost-effectiveness ranking
Recommended order of EPC improvements
Insulation first
Loft to 270mm, cavity walls if applicable plus hot water cylinder. Cheapest per SAP point. Cuts heat demand.
Heating system
Modern A-rated boiler if old, smart controls plus zone valves. Improves efficiency of remaining heat demand.
Glazing if needed
Replace single glazing with double. Existing double with triple rarely worthwhile for SAP gains alone.
Renewables for big jump
Solar PV (£5-10k) for biggest single jump. Heat pump (£7.5-13k with grant) replacing gas boiler. Most impact for D to B.
Four EPC improvement priorities for UK homes
Insulate before generating
Solar PV on a poorly-insulated home wastes most of the benefit. Insulate first plus generate second.
Get the new EPC after works
Existing EPCs do not auto-update. Commission a fresh EPC after major improvements to capture the new rating.
Apply for relevant grants
Boiler Upgrade Scheme £7,500 for heat pumps. ECO4 plus Great British Insulation Scheme for eligible households.
Plan toward 2030 EPC C minimum
Rentals must reach EPC C by October 2030 with £10,000 cost cap. Plan upgrades early to spread cost.
Compare the options
Cost-effective improvement path
- ✓Insulation first. £1,000 to £3,000 for 10 to 25 SAP points.
- ✓Heating system second. Modern boiler or controls add 3 to 8 points.
- ✓Solar PV last. £5,000 to £10,000 for 8 to 20 points on a well-insulated home.
- ✓Total £7,000 to £15,000 typical for D to C journey.
- ✓Apply for grants. Boiler Upgrade Scheme plus ECO4 reduce costs.
Expensive scattershot path
- ✗Triple glazing first. £8,000 to £20,000 for 1 to 3 points only.
- ✗Solar PV without insulating first. Most output wasted on heat loss.
- ✗New boiler before insulation. Oversized for actual heat demand after insulation.
- ✗Total £25,000+ for similar SAP gains.
- ✗Skip available grants. Pays full retail for everything.
Improving EPC rating is one of the most common landlord plus homeowner questions. Our full EPC Ratings hub covers Energy Performance Certificates plus MEES regulations across UK homes plus rental properties.
Visit the EPC Ratings Hub
This article is one chapter inside our complete EPC Ratings knowledge base. The hub covers Energy Performance Certificates plus MEES regulations across UK homes plus rental properties.
More on EPC ratings
Three further EPC improvement articles in the same hub group cover related questions. The first is how to improve epc rating from d to b for the major-jump journey. The second covers how to improve epc rating from e to c for the rental compliance path. The third is what is a good epc rating for the rating context.