How to Improve EPC from D to C: Cheapest Options & Expected Costs

If your property is EPC band D, you’re in good company – it’s one of the most common ratings in England and Wales. But with rising energy costs and tighter rules on the horizon, many owners now want to get to band C.

The jump from D to C usually doesn’t require a full-scale renovation. Instead, it’s about choosing the right combination of insulation, heating and control upgrades – and doing them in the right order.

This guide focuses on:

The cheapest options to move from D to C
Typical costs and bill savings for each measure
How to prioritise improvements using your EPC report

Before you start, look up your current EPC using our free EPC checker and open your property report.

Step 1: Understand your current D rating

Two different D-rated homes can have very different improvement paths.

Check your current and potential scores

On your EPC:

Note the current SAP score (e.g. D 62).
Note the potential SAP score if all recommended measures are completed (e.g. B 82).

The closer you already are to band C (69+), the fewer improvements you’ll need.

Review recommended measures

Your EPC lists recommended improvements, typically ordered by cost-effectiveness. Common examples include:

Loft insulation top-up
Cavity wall insulation
Floor insulation (suspended floors)
Heating controls upgrade
New boiler or heat pump
Solar panels or hot water improvements

We’ll now map these to typical costs and EPC impact so you can decide where to start.

Step 2: Low-cost upgrades that help push D towards C

These improvements alone might not move you a full band, but they set the stage and help on the margins.

1. Loft insulation top-up (if under-insulated)

If your loft has less than 270mm of insulation, topping up is often the first major step.

Typical cost: £300–£600 (DIY or installer)
Savings: £150–£250 per year
EPC impact: Often +5–10 SAP points

For many D-rated homes, loft insulation plus one other major measure is enough to tip into C. Read more in Does Loft Insulation Improve Your EPC?.

2. Heating controls upgrade

If your EPC notes limited or missing controls, upgrades can be high-value:

Add a room thermostat and programmer if you don’t have them.
Install TRVs on radiators to control room-by-room temperatures.
Consider a smart thermostat for more precise control.

Typical cost: £200–£500, with moderate EPC gains and immediate comfort improvements.

3. Targeted draught proofing

Especially in older homes, draughts around doors, windows and floors can lead to higher heating demand.

Install draught-proof strips, letterbox brushes and chimney balloons (where appropriate).
Seal obvious gaps using suitable products (avoid blocking essential ventilation).

These measures won’t transform your EPC on their own, but they improve the effectiveness of bigger upgrades.

For budget-first options, see Cheapest Ways to Improve Your EPC Rating.

Step 3: High-impact measures likely to move you from D to C

To gain a full band, most D-rated homes will need at least one of the following, sometimes in combination with low-cost steps.

4. Cavity wall insulation (where suitable)

If you have uninsulated cavity walls, this is often the single most effective upgrade for moving from D to C.

Typical cost: £800–£1,500
Savings: £150–£300 per year
EPC impact: Often +10–15 SAP points

Check your EPC and property type. If it mentions “Cavity wall – no insulation (assumed)”, get a professional survey to confirm suitability and quote.

5. New A-rated gas boiler (from very old systems)

If your boiler is old and inefficient, replacing it with a modern condensing boiler can:

Improve efficiency to 90%+
Reduce gas usage and bills
Deliver useful EPC gains, especially when paired with good controls

This is particularly relevant if your EPC shows your heating system as a weak point or recommends a boiler upgrade. Dive deeper in Does a New Boiler Improve Your EPC? and see price ranges in New Boiler Cost UK (2025 Guide).

6. Upgrading electric heating in flats

For electrically heated properties (e.g. with old storage heaters), moving towards:

High-heat-retention storage heaters, or
Efficient electric systems with smart controls

can trigger significant EPC changes due to how the calculation treats electric heating. Because this is complex and property-specific, it’s worth getting advice from an assessor or installer before investing.

7. Floor insulation for suspended timber floors

If you have ventilated timber floors:

Insulating from below (where accessible) can cut heat loss.
Typical cost ranges from £800–£2,000, but partial work may still help.

This measure is more disruptive, so it’s often best tackled alongside other works.

Step 4: Major upgrades that can leapfrog you to C (and beyond)

For some D-rated homes, particularly those already near the top of the band, one major upgrade may be enough to reach C or even B.

8. Air source heat pump (in well-insulated homes)

If your property is already well insulated, an air source heat pump can significantly improve both your EPC and carbon emissions.

Strongest results in homes with good fabric efficiency and sized radiators.
Often eligible for grants, such as the Boiler Upgrade Scheme.

See Air Source Heat Pump Costs UK and Boiler vs Heat Pump: Cost Comparison for costs and suitability.

9. Solar PV panels

Solar panels help by offsetting electricity use rather than reducing heat demand, but they still improve EPC scores.

Typical cost: £4,000–£8,000+ depending on system size.
Savings: Vary with usage patterns and export tariffs.

For a focused breakdown of EPC impact, see Solar Panels and EPC Rating.

10. Solid wall insulation (for older homes)

If you’re in a period property with solid walls, internal or external wall insulation can have a huge effect – but it’s a major project.

Very effective for heat loss reduction and EPC scores.
Expensive and potentially disruptive – often best combined with refurbishments.

For heritage-sensitive guidance, see How to Improve EPC on Victorian House.

How much will it cost to go from D to C?

Because every property is different, there’s no single price tag. But a common pattern for D → C is:

£300–£600 for loft insulation top-up (if required)
£800–£1,500 for cavity wall insulation (if available)
Optional £200–£500 on controls/draught proofing

Total: Many homes can move from D to C for roughly £1,000–£2,000 if they’re starting from a reasonably efficient baseline.

If major systems (boiler, windows, walls) are outdated, costs may be higher – but so will the comfort and bill savings.

Grants and help for getting to band C

You may not have to fund everything yourself. Depending on your income, location and heating system, you may be eligible for:

ECO4 and related schemes for insulation and heating upgrades
The Boiler Upgrade Scheme for low-carbon heating
Local authority grants for low-income or vulnerable households

We cover the landscape in Home Energy Grants UK 2025: Complete Guide to Funding (/insights/home-energy-grants-uk). Use this alongside our main cost guide, New Boiler Cost UK (2025 Guide), if a boiler upgrade is part of your D → C plan.

Landlords: D to C for rentals

If you’re a landlord, the D to C journey ties directly into compliance:

Current minimum standard is generally band E (with exemptions).
The government has proposed raising minimum standards towards band C for rentals.

Improving from D to C early can help you avoid a last-minute scramble later. For a full overview of the rules, exemptions and potential fines, see:

FAQs

What is the EPC score for band C?

Band C covers EPC SAP scores of 69–80. If your current rating is D 68, you may only need a small improvement; if you’re D 55, you’ll need more substantial upgrades.

What are the cheapest ways to move from D to C?

For many homes, the best value sequence is:

Loft insulation top-up (if needed).
Cavity wall insulation where available.
Heating controls and draught proofing.

If you still fall short, consider a boiler upgrade or other larger works.

Do I need a new EPC after making improvements?

Yes. The EPC doesn’t automatically update. Once you’ve completed major upgrades, you’ll need to book a new assessment. Use Is My EPC Still Valid? to check whether you also need to replace an expiring certificate.

What should I do next?

Use our EPC checker to confirm your current rating and recommendations.
Make a shortlist of measures from this article and your EPC report.
Read Cheapest Ways to Improve Your EPC Rating to order them by budget.
Plan works over 6–24 months, starting with insulation and controls, then tackling heating and renewables as budget allows.

If you’re starting from band E rather than D, see How to Improve EPC from E to D for a more foundational roadmap.