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Climate action: Seven steps to insulate your home

Heating our homes can cost a lot in terms of carbon, as well as energy bills. In fact, around 14% of our total emissions comes from heating our homes, workplaces and public buildings. 

By improving our insulation, we can significantly reduce the amount of energy we use – making it one of ten key climate actions you can take to cut your carbon footprint. 

Here, we provide a roadmap to insulating your home.

In order to meet the UK’s decarbonisation targets, we need to insulate 3 million cavity walls, 11 million lofts, 3 million solid walls and 3 million floors before 2030. 

Luckily, insulating our homes is great for us too. Homes insulated in the last tens years saved 20% from their gas bill – and associated carbon – every year. 

Seven steps to insulate your home

Insulating your home can seem like a bit of a confusing task. There are so many options from wall and loft insulation to floors and even pipes; and it can cost anywhere from a hundred to several thousand pounds, depending on what you choose to do. But it’s also a great option for saving money in the long term.

This step-by-step guide will help you work out what insulation is right for you.

1. Consider different kinds of insulation available

Roof insulation

An uninsulated house could be losing up to 25% of its heat through the roof. Loft insulation is one of the best value options out there, so if you don’t already have it, it’s a good place to start.

If you have an easy-to-access loft, you may be able to insulate it yourself. Think about storage space, inaccessible areas and dampness before starting the work or getting a professional to help you. There are lots of videos on YouTube with advice on how to do a DIY job.

Wall insulation

Around one third of all the heat lost in an uninsulated home escapes through the walls.

You will need to work out your wall type (see below). Most houses have either cavity or solid walls. For cavity wall insulation, a professional can inject insulation material into the space. If your walls are solid, an insulation layer can be attached either inside or outside your home. Both require a trained installer.

Most houses built within the last 20 years or so will already have wall insulation.

Energy Saving Trust have great guides to wall insulation >

Floor insulation

If you live on or have a ground floor in your home, you may want to consider insulating it. The type of insulation you need will depend on your type of floor. It will be much easier and cheaper if you have a suspended floor, e.g. over a basement or cellar.

If you do have an easily accessible, unheated basement or cellar underneath, you could fit this kind of insulation yourself. Check that the joists supporting the floorboards are in good condition, and there are no signs of wet or dry rot.

Energy Saving Trust has instructions on how to fit DIY floor insulation >

For a quick fix, you can seal gaps between floors and skirting boards to reduce draughts, using sealant from a DIY store. Rugs and carpets can also help keep your feet warm.

Pipe insulation

Insulating pipes, radiators and your water tank is a quick and easy option to save on energy bills. You can buy DIY fixes like hot water cylinder jackets, pipe insulation and radiator reflector panels.

Energy Saving Trust has great guides for understanding what type of insulation might work for you. Alternatively, you can get advice from a builder or retrofit assessor. (See below.)

Insulation for windows, doors and chimneys

It’s amazing how much you can save from draught-proofing your house. For example, if you have an open chimney that you’re not using, draught-proofing it could save you £65 a year.

Draught-proofing may be a good option for renters too, if your landlord is happy to give you permission.

Paying a professional to draught-proof your whole home will cost around £225, but DIY will be considerably cheaper. Check your windows, doors, chimneys, floorboards and skirting boards, loft hatches, pipework, old extractor fans or cracks in the wall.

Make sure you don’t block any extractor fans, underfloor grilles or airbricks, wall vents or trickle vents above windows: these are designed to be sources of ventilation to keep your house fresh, dry and healthy. Be particularly careful to allow ventilation in rooms where there are open fires or that have lots of moisture such as bathrooms or kitchens.

Energy Saving Trust has a full guide to draught-proofing your home >

2. Work out what insulation you could fit in your home

To make a decision on what kind of insulation to get, you’ll need to understand the structure of your home. Gathering this information will also help you work out what you can do yourself and what you’d need a professional for. There are a few easy questions you can ask to begin with:

  • Does my home have an accessible loft? If so, insulating your loft can be relatively easy, and a possible DIY option.
  • Does my home have a suspended floor? The easiest way to check this is to look for air vents or ventilation bricks at the bottom of your walls. Suspended floors are much easier and cheaper to insulate than solid ones.
  • Does my home have an accessible, unheated cellar or basement? If so, you may be able to insulate your floor yourself.
  • What kind of walls does my home have? If you have bricks on the outside of your house, their pattern will tell you how your walls have been built. If you have solid walls, some bricks will have been laid lengthways, and some will have been laid with the short end out: look for an alternating pattern. If you have cavity walls, all bricks are likely to have been laid lengthways. Cavity walls will need cavity wall insulation. Solid walls will need a layer of insulation adding either on the inside or the outside.
  • Is my home draughty? There is lots you can do in the way of draught-exclusion as an easy first step.
Infographic with two pictures of different wall types, cavity and solid.

3. Consider what you can afford

How much it costs to insulate your home very much depends on what you decide to do, as well as how big it is. For example, cavity wall insulation will cost around £2,500 for a detached home vs £410 for a mid-floor flat. Luckily, if you have a big house, insulation is all the more worthwhile. For example, a detached home has lots of walls to lose heat from and will generally have much higher energy bills and associated emissions.  

We used figures from Energy Saving Trust to calculate the following:

  Approx cost DIY approx cost Annual saving Payback period
Cavity Wall £410 – £2,500 - £145 – £480 3 – 5 years
Solid Wall Internal £10,000* - £390 25 years
Solid Wall External £14,000 - £390 35 years
Loft £500 – £690 £250 – £600** £230 – £580 1 – 2 years
Floor £1,300 – £2,700*** £115**** £50 – £130

2 years DIY
20 – 25 years professional

* Based on a typical 3 bedroom semi-detached house in Great Britain.
** Based on using Fibreglass Blankets. Figures from HomeownerCosts.
*** For suspended floor installation. Solid floor installation could cost considerably more.
**** For suspended floor installation in a mid-terrace house. Figures from Which?

Depending on the structure of your house, and what you already have in place, only some options will be open to you. It’s probably also worth thinking about how long you’re likely to stay in your home. This way you can better understand the payback potential.

Energy Savings Trust points out that there are often ways to make it cheaper, if you can’t afford the full quotes above. For example, it points out that the costs of internal solid wall insulation above are based on getting all the work done in one go, including fully redecorating your home. You can make it cheaper by doing a room at a time when you plan to redecorate or get a new kitchen or bathroom fitted anyway.

Energy Savings Trust recommends getting at least three quotes from different installers if paying to have the work done.

4. Get some advice

If you’re unsure what insulation would work best in your home, you can get a builder to come and make an assessment for you.

You may want to consider doing this as part of a larger retrofit assessment. A retrofit assessor will visit your house, speak to you about how you use the space and your own needs and recommend possible measures to reduce your energy use and carbon emissions. Recommendations can cover everything from small behaviour change to insulation or getting a heating pump. They will estimate costs and carbon savings for each option, and suggest stages for making any retrofits.

The advantage of getting a full assessment is that they will be able to tell you the best option for you: you may find that some options have a much better cost-to-benefit than others when it comes to your home. A retrofit assessment does cost though, averaging around £180 for the initial assessment and report.

TrustMark has an introductory page or a more detailed guide to getting a retrofit assessment.

If you are a homeowner and want to arrange a retrofit assessment, you can contact Retrofitworks through their website to arrange an initial appointment. TrustMark also has a directory of tradespeople, including builders and retrofit assessors.

A well qualified assessor will have trained with a trusted specialist retrofit training body, such as the Retrofit Academy.

5. Check for financial support

You may be able to get government support for improving the energy efficiency of your home.

In England, Scotland, Wales or Ireland, those receiving benefits may be eligible for energy efficiency improvements from their energy company. You can contact your energy company directly to get a free assessment. There are lots of things energy companies may offer, but they most often focus on loft and cavity wall insulation. Some might ask you to pay a proportion of the costs.

Find out more >  

If you’re not eligible for this or any of the below, you may be able to find a local grant. Check online >

Scotland

In Scotland, some may be eligible for an assessment and free home improvements through Home Energy Scotland – for example if you’re a pensioner or have a child under 16 and receive Passport Benefits, or you receive a disability or carers allowance.

Find out more >

Home Energy Scotland also provides considerable loans and cashback for certain home energy efficiency improvements and home renewables, including:

  • Solid wall insulation: up to £10,000 (£6,000 loan plus £4,000 cashback)
  • Glazing: up to £4,500 (£4,100 loan plus £400 cashback)
  • Insulated doors: up to £4,500 (no cashback available)
  • Flat roof or room-in-roof insulation: up to £4,000 (£2,400 loan plus £1,600 cashback)
  • Loft, floor or cavity wall insulation: up to £1,000 (£600 loan plus £400 cashback)

Find out more >

Wales

The Welsh Government scheme Nest provides free advice to all on making your home warmer and more energy efficient. Those who are eligible for means-tested benefits and live in a hard-to-heat home can also receive a free assessment and free home improvements, including insulation. This includes those renting privately.

Find out more >

Northern Ireland

In Northern Ireland, NISEP provides grants for energy saving measures. Under its 2022-23 schemes, both cavity wall and loft insulation can be fully funded. Each scheme has a different income cap in terms of who is eligible, but you should be able to get insulated if you earn less than £35,000 as a single homeowner, or £40,000 as a couple or single parent.

Find out more >

Schemes periodically change, so it’s worth doing an internet search to check for anything new or checking the Energy Saving Trust website.

Person counting money on desk with notepad

6. Work out what you can do yourself

You may be able to install loft and floor insulation yourself. You will still have to pay for materials, and maybe some equipment, but it will certainly cost less than paying a professional (see table above).

Check whether you have a roof space you can easily access, or an unheated cellar or basement with access to your joists. Before starting any work, make sure there isn’t any damage, damp or dry rot on your joists or ceiling. YouTube has lots of video tutorials you can follow to make sure you do it correctly, and Energy Saving Trust is a great source of information.

Before doing major work, there is also some minor insulating you can do yourself. For example, you can easily insulate pipes using foam tubing or seal holes between skirting and floorboards with sealant to exclude draughts. You can close holes around windows using metal or plastic strips, or fit a brush or hinged flap below your front door.  

Energy Saving Trust has a full guide to draught-proofing your home >

7. Find a qualified installer

If paying a professional, make sure they are fully qualified.

For solid wall, underfloor, flat roof or room-in-roof insulation, your installer must be Green Deal certified. Check what guarantees and warranty they provide for the work.

For getting cavity wall insulation, Energy Saving Trust recommends finding an installer from the National Insulation Association, Cavity Insulation Guarantee Agency or Board or Agrément. It also suggests finding someone who offers an appropriate 25-year guarantee.

Get inspired: Hear how Fran took action

I’d always been pretty conscious about saving energy around the house but in the past this has probably been more to do with my wallet than my carbon footprint! It was moving into my own house a couple of years ago that really inspired me to see how much I could actually reduce the energy I consume around the home.

While I was buying my house, I was reading about green mortgages and how important improving the energy efficiency of old houses is for reducing our carbon footprints. Reducing the amount of direct fossil fuels I used in my home seemed like a very immediate way to affect my impact.

As I’m stuck with using gas for heating and hot water, I turned my attention to using as little of it as possible. I’m currently using between 2,000 and 3,000kwh a year – at least 5,000kwh below what is considered typical low usage for a household – and have not been sitting in a cold house.

I learnt that we feel more cold in damp humid air so if you can reduce the humidity you can turn your thermostat down without feeling a chill. I invested in a low-energy dehumidifier (and use the water on the plants). I had fun smashing off some gypsum plaster board on a damp wall and replacing it with lime plaster which lets the house ‘breath’ as it was designed too.

As most heat is lost through windows and doors, I’ve added secondary glazing to some windows (just a perspex sheet stuck to the inner window frame with magnet strips – pretty easy to do and completely reversible). I also hung insulating curtains over doors (I’m making wooden pelmets too – apparently they have an actual function).

I can now keep my thermostat at 18 degrees and feel completely comfortable. I also don't need to use my heating all of the time.

As my home is currently heated by gas, I can also see how much I was using from my gas meter and energy bills. I can therefore see how much I have saved from turning down my heating and in some cases, turning it off completely.

Why is insulating our homes important?

Our heating accounts for around 14% of our total emissions. About 77% of that is from homes, 14% commercial buildings and 9% public buildings.

We must cut heating use by at least 12% by 2030 in order to meet the UK’s decarbonisation goals, and the majority of this will come from insulating our homes.

According to i news, “Upgrading homes from EPC band D – the average in England and Wales – to EPC band C results in a 20 per cent cut in gas demand per home.” This means that households insulated in the last decade are saving on average £200 from their gas bill each year.

According to the Energy Saving Trust, internal solid wall insulation for a semi-detached house, for example, will cost around £8,200, but could save you around £255 a year on energy bills.

The bigger picture

In October 2021, Ethical Consumer published a report looking at consumer action on climate change. It looked at ten key actions consumers must take for the UK to reach its emissions reductions goals, and how far we are from meeting them.

It found that without further action, we would miss all ten key consumer targets.

When it comes to cutting emission from heating our homes, the first priority is reducing heating use through insulation and changing our behaviour.