Home Improvement

Energy Efficient Home Upgrades UK: A Practical Guide

Energy efficient upgrades save money, cut carbon and make UK homes more comfortable. Here is a practical, evidence-based guide to the upgrades that actually work.

By Ahsan 11 min read
Half Wall Paneling Ideas
Half Wall Paneling Ideas
by

UK homes are among the least energy efficient in Europe. The average UK home loses heat through the roof, walls, windows, floors and draughts, and runs on a gas boiler that has been the standard heating technology for 70 years. Energy efficient upgrades save money, cut carbon and make homes more comfortable, but not every upgrade is worth the money. This guide is a practical, evidence-based walkthrough of the upgrades that work, the ones that do not, and how to fund the work through UK government grants.

Table of contents

Where UK homes lose heat

Before choosing upgrades, it is worth understanding where the heat goes. The Energy Saving Trust and Department for Energy Security and Net Zero publish average heat loss figures for UK homes. Roughly, for an uninsulated 1930s semi:

  • Walls: 30 to 35 per cent of heat loss
  • Roof and loft: 25 per cent
  • Windows and doors: 20 to 25 per cent
  • Floor: 10 to 15 per cent
  • Draughts: 10 to 15 per cent

The pattern is consistent across most UK homes built before 2010: walls, roof and windows are the priority. The order of upgrades matters. Insulating the walls or roof before the heating system is the right answer; replacing the boiler before the walls are insulated is the wrong one.

The priority order of upgrades

For most UK homes, the upgrades pay back in roughly this order.

  1. Draught-proofing – the cheapest upgrade, the fastest payback, and the foundation for everything else
  2. Loft insulation – cheap, easy to install, immediate savings
  3. Smart heating controls – saves 10 to 15 per cent of heating bills with no other work
  4. Cavity wall insulation – the standard upgrade for 1930s onwards homes
  5. Hot water insulation – pipe and cylinder lagging, very cheap
  6. Floor insulation – only worthwhile when the floor is being replaced anyway
  7. Double or triple glazing – only after the walls and roof are done
  8. External or internal solid wall insulation – expensive but transformative
  9. Solar panels – the right answer for a south-facing roof
  10. Heat pump – the right answer once the home is properly insulated

Loft and roof insulation

Loft insulation is the cheapest, most cost-effective upgrade in a UK home. The current recommended depth is 270mm of mineral wool, which gives a U-value of around 0.16 W/m²K. For a typical 3-bed semi, the work takes a professional half a day and costs £300 to £600.

For a cold loft, the insulation sits between and over the ceiling joists, with the loft floor left unboarded. For a warm loft, the insulation goes between and under the rafters, leaving the loft space usable. Warm loft insulation costs two to three times more but is worth it if the loft is being used as a room.

Use Knauf, Rockwool or Celotex rigid PIR boards for warm-loft conversions. For cold lofts, mineral wool rolls from any builders’ merchant are the right answer.

Cavity wall and solid wall insulation

For homes built between 1920 and 2010 with a cavity wall (two leaves of brick with a gap in between), cavity wall insulation is the right answer. The work is fast, low-disruption, and a PAS 2030 certified installer can usually do the work in a day. The cost is £400 to £800 for a typical semi, with savings of £200 to £400 per year on heating.

For homes built before 1920 with a solid wall, the choice is between external wall insulation (EWI) and internal wall insulation (IWI). EWI is more expensive (£10,000 to £18,000 for a typical semi) but does not reduce internal floor area. IWI is cheaper (£5,000 to £9,000) but loses 50mm to 100mm of internal wall and is more disruptive.

For a UK Victorian or Edwardian terrace, EWI is the right answer if the budget allows. The home becomes a different thermal unit, with no internal disruption. For a listed building, IWI may be the only option, since the external appearance is protected.

For solid wall homes, also consider Historic England guidance before any external work. EWI on a listed building needs Listed Building Consent.

Floor insulation

Suspended timber floors can be insulated from below with mineral wool between the joists, or from above with rigid PIR boards if the floor is being replaced. Solid concrete floors need rigid insulation laid before the screed or floor finish.

For most UK homes, floor insulation is only worth doing when the floor is being replaced anyway. A standalone retrofit is expensive and disruptive for limited additional savings.

Windows and doors

Double or triple glazing is the most visible UK energy upgrade, and the most overhyped. For most homes, replacing single glazing with double glazing saves around £80 to £120 per year on heating. At a cost of £5,000 to £15,000 for a full house, the payback is 20 to 30 years.

The right answer for most UK homes is to repair existing windows, draught-proof them, and only replace them when they are at the end of their life. For a Victorian sash window that is structurally sound, secondary glazing is a much cheaper option, with 80 per cent of the thermal performance of new double glazing.

When you do replace, look for BFRC-rated A-rated windows, with a U-value of 1.2 W/m²K or better. Triple glazing is only worth it for north-facing or very exposed windows.

For external doors, a composite door with a U-value of 1.0 W/m²K or better is the right answer. Replace the letterbox and keyhole with draught-proofed versions, and fit a brush seal at the bottom.

Draught-proofing

Draught-proofing is the cheapest, most cost-effective energy upgrade in a UK home. A tube of silicone sealant, a roll of foam tape, and a few brush strips will cost £30 to £80 and save £50 to £100 per year on heating. Do this first, before any other upgrade.

The key areas.

  • Windows: Foam tape around the frame, silicone sealant around the outside
  • External doors: Brush seals on the bottom, foam tape around the frame, keyhole and letterbox covers
  • Loft hatch: Foam tape around the frame, a compressible seal on the hatch itself
  • Pipe and cable penetrations: Silicone sealant or expanding foam around any pipe or cable passing through an external wall
  • Chimneys: A chimney balloon or a register plate if the fireplace is not in use

Be careful not to over-seal a home. Kitchens, bathrooms and utility rooms need ventilation to prevent condensation and damp. Aim for a balance: sealed but not airtight.

Heating systems and the heat pump question

UK heating is changing. The Heat and Buildings Strategy sets out the route to phase out new gas boilers by 2035, and the Microgeneration Certification Scheme (MCS) provides a quality standard for low-carbon heating.

For most UK homes, the question is whether to replace a working gas boiler with a heat pump now, or wait. The honest answer depends on the home.

  • For a well-insulated home with underfloor heating or large radiators: An air source heat pump is the right answer. It will cut heating bills by 30 to 50 per cent and produce 3 to 4 times less CO₂ than a gas boiler.
  • For an average 1930s semi with a gas boiler: A heat pump will work but the radiators may need to be upgraded to operate at lower flow temperatures. Budget £7,000 to £13,000 for the heat pump and £1,500 to £3,000 for the radiator upgrade.
  • For a poorly insulated home: Insulate first, then consider a heat pump. A heat pump in a leaky home will run constantly and never heat the home properly.

For a UK home with no gas supply (an off-grid rural property, for example), a heat pump is usually the right answer regardless, often combined with a RHI or successor tariff.

Hot water

Hot water is around 20 per cent of a typical UK home’s energy bill. Three upgrades that help.

  • Cylinder insulation – a hot water cylinder should be lagged with at least 80mm of factory-applied foam. If the cylinder is old, a British Standard jacket from Screwfix or Wickes will do the same job. £20 to £40.
  • Pipe insulation – all hot water pipes should be lagged with at least 19mm of foam pipe insulation. £10 to £30 for a typical home.
  • Smart hot water controls – a timer and thermostat on the hot water cylinder can save 10 to 15 per cent of hot water costs.

For new builds and full refurbishments, an instantaneous hot water system or a solar thermal system can replace the cylinder entirely. Both are usually only worthwhile as part of a larger refit.

Solar panels and batteries

Solar PV is one of the most cost-effective UK energy upgrades for a south-facing roof. A typical 4kW system costs £5,000 to £7,000 installed and generates 3,500 to 4,500 kWh per year, equivalent to £700 to £1,000 of electricity at 2025 prices. Payback is 5 to 8 years.

A MCS-certified installer is essential for any Smart Export Guarantee (SEG) payments and most insurance policies. The Renewable Energy Hub lists accredited installers in your area.

A home battery (£4,000 to £8,000 for a 5kWh to 10kWh system) makes sense if you use a lot of electricity in the evening, or have a heat pump. For a typical UK home, the payback is 10 to 15 years without a heat pump, and 5 to 8 years with one.

Smart heating controls and TRVs

Smart heating controls are one of the cheapest upgrades with the biggest impact. A Google Nest, Tado° or ecobee thermostat, plus smart thermostatic radiator valves (TRVs) on each radiator, will save 10 to 15 per cent of heating bills with no other work. The cost is £200 to £500 for a typical 3-bed home.

Smart TRVs are particularly useful in UK homes where one room is always too hot (the living room) and one is always too cold (the spare bedroom). Each room can be on its own schedule, which makes the whole home more comfortable.

UK government grants and funding

UK funding for energy efficiency changes regularly. The main schemes in 2025 are:

The Simple Energy Advice service, run by the Energy Saving Trust on behalf of the government, gives free, impartial advice on which upgrades are right for your home and what funding you can claim. The service is independent of installers.

UK cost guide

Typical UK upgrade costs in 2025 prices, for a 3-bed semi.

  • Draught-proofing (DIY): £30 to £80
  • Loft insulation (270mm mineral wool): £300 to £600
  • Smart heating controls (thermostat + TRVs): £200 to £500
  • Cavity wall insulation: £400 to £800
  • External wall insulation: £10,000 to £18,000
  • Internal wall insulation: £5,000 to £9,000
  • Double glazing (whole house): £5,000 to £15,000
  • Air source heat pump: £7,000 to £13,000 (after BUS grant, £0 to £5,500)
  • Solar PV (4kW): £5,000 to £7,000
  • Battery (5kWh): £4,000 to £6,000

For most UK homes, a sensible sequence is: draught-proofing + smart controls + loft insulation + cavity wall insulation, all done over a year or two, for a total of £1,000 to £2,000. Solar panels and a heat pump come later, when the home is properly insulated.

Related reading. Energy saving tips for UK homes · Wall panelling ideas UK · Garden privacy ideas UK · Multifunctional furniture for small UK homes.

Frequently Asked Questions

1. What is the most cost-effective energy upgrade in a UK home?

Draught-proofing, by a wide margin. A £30 to £80 DIY job will save £50 to £100 a year on heating, with a payback of under a year. After that, loft insulation and smart heating controls are the next most cost-effective upgrades.

2. Are heat pumps worth it in the UK?

For a well-insulated home, yes. An air source heat pump will cut heating bills by 30 to 50 per cent compared with a gas boiler, and the running cost is much more stable. For a poorly insulated home, insulate first. A heat pump in a leaky home will run constantly and cost more than a gas boiler.

3. How do I get an energy performance certificate (EPC)?

An EPC is required when a UK home is sold, let, or modified. It is produced by a qualified domestic energy assessor. The cost is £60 to £120 and the assessment takes 30 minutes to an hour. The result is a band from A (most efficient) to G (least efficient), with recommendations for upgrades.

4. Are solar panels worth it in the UK?

For a south-facing roof, yes. A 4kW system costs £5,000 to £7,000 and pays back in 5 to 8 years, after which the electricity is essentially free. For a north-facing roof, no – the payback is 15 to 20 years, and east or west is borderline. Use the gov.uk solar roof potential map to check your roof.

5. What is the Boiler Upgrade Scheme?

The Boiler Upgrade Scheme (BUS) is a UK government grant of £7,500 towards an air source heat pump, £7,500 towards a ground source heat pump, or £5,000 towards a biomass boiler. The grant is paid to the installer, who deducts it from the quote. You apply through an MCS-certified installer.

6. Should I insulate before or after getting a heat pump?

Always before. A heat pump in an uninsulated home will run constantly and never heat the home properly. The insulation upgrade pays for itself in lower running costs, regardless of the heating system.

Final thoughts on energy efficient home upgrades

Energy efficient home upgrades are a long game. The most expensive upgrades – solid wall insulation, a heat pump, a solar array – are also the most cost-effective over 20 to 30 years, but only if the cheaper upgrades have already been done. Start with the cheap, fast wins: draught-proofing, loft insulation, smart controls. Then move to the bigger projects: cavity wall insulation, double glazing, a heat pump.

For more on the wider project, see our guides to smart thermostat buying guide and appliance garage kitchen ideas.

Share this article

Keep reading