The ultimate guide to home insulation: costs, savings and benefits

07 November 2020 | Matt Mostyn

A warm, cosy home is a must over winter – and insulation is the best way to make your house warmer and reduce those winter bills. Find out more with our complete guide to insulating your home.

home insulation guide

There’s one guaranteed way to help reduce your energy bills and your home’s carbon emissions. Insulation!

Insulating your home is one of the best steps you can take to reduce heat loss at home. And as we move into winter, there’s no better time to make improvements that could cut your winter bills, save you money, and also help save the planet. 

Even little fixes can have a big impact. For instance, pop an insulating jacket on your hot water cylinder and you’ll save around £35 per year in heating costs. Which is more than the cost of the jacket itself.

Here’s a complete run-down of the many steps you can take to insulate different parts of your home and enjoy better energy-efficiency. Jump in, take action, and enjoy the feeling of knowing you’ve done something good for your wallet and the planet this winter!

What is home insulation, and why’s it important?

If a building’s not insulated, as much as half of its heat can escape through the roof, walls, windows and floor. Poor insulation makes a home very hard to keep warm, and also very expensive to heat. That’s because when left unchecked, heat will naturally flow from warmer to cooler spaces until there’s no temperature difference. 

In a typical home, your walls lose the most heat – as much as 30% to 40%! Your roof is next, losing around 25% – followed by windows and doors at around 15-20%, and your floor can lose around 10%1.

But when you insulate, it’s like throwing a big, cosy blanket around your home. And that helps it to more easily maintain the temperature you set on your thermostat. It also means you won’t need quite so many blankets yourself this winter.

How heat escapes from your home

Heat can escape from your home in a few different ways:

  • Conduction – this is when heat moves through solid surfaces such as metal or brick.
  • Radiation – this carries heat directly from warm objects to cooler objects. In your home, heat radiation is often lost through the wall behind a radiator if that wall isn’t insulated.
  • Convection – this happens when warm air rises. In an uninsulated wall space, air picks up heat from the warm side of the wall and circulates it to the cold side.
  • Air movement – draughts are another common form of heat loss. That’s because they take warm air from within the home and move it outside (while also replacing it with cold air coming in). 

The benefits of home insulation

  • A well-insulated home reduces heat loss in cold weather – and it can even help to minimise heat gains when it eventually gets warmer! All of which makes for a much more pleasant and comfortable home life, whatever the weather.
  • Insulation is also a brilliant way to reduce noise pollution. If you live near a busy road or under a flight path, insulation is a must-do – as it’ll really help to minimise medium-to-high-frequency noise from outside. 
  • More good news? Any key insulation measures are  considered low cost – meaning that they'll pay for themselves in less than 5 years.
  • Insulating our homes also helps to address one of the most important issues of our time – climate change. When we use less energy, we burn less fuel, and that’s vital in our efforts to stop tons of unnecessary carbon from being released into the atmosphere. 
  • Put simply, reducing our demand for energy is one of the best things we can do to prevent further climate change and help protect the planet. Sold yet?!

And there’s more good news too – because right now, the Green Homes Grant helps you cover the cost of home insulation improvements. Find out more about that below.

5 steps to insulating your home

As the diagram below shows, there are 5 main areas to focus on when it comes to properly insulating your house. Let’s go through them one by one:

diagram on how to insulate your home

1. Loft and roof insulation

You can lose up to 25% of your home’s heat through an uninsulated roof2. You likely already have some – but even if you just decide to add an extra layer to existing insulation, it can still help to lower your heating bills and reduce your carbon footprint.

Read more about all the benefits in our ultimate guide to roof and loft insulation

2. Cavity wall insulation

Whether yours are cavity or solid walls, insulating them properly will help keep heat in. The type of walls you have depends very much on when your house was built. As a rough guide, solid wall constructions are often pre-1919, while uninsulated cavity walls are usually found in brick and block buildings built between 1920 and 1975. Most built after that will also have cavity walls.

Stop heat escaping through your cavity walls and you’ll reduce heat loss by as much as 40% – making this a potentially highly cost-effective way to retain heat in your home and save money on your bills. 

It’s estimated that cavity insulation could save you up to £160 a year in heating bills.

Find out more in our guide to cavity wall insulation

3. Solid wall insulation

Did you know that solid walls let twice as much heat escape as cavity walls? For a detached house, insulating solid walls could save you as much as £375 a year3.

Our guide to solid wall insulation has more!

4. Underfloor insulation

If your home has a particularly draughty floor, you could first try some quick fixes, such as plugging the holes, filling gap-ridden skirting boards or adding a couple of rugs. But if you’re planning on changing the floor anyway, laying new carpet, or renovating downstairs, this could be a great time to add some insulation. Doing that alone could reduce heat loss in your home by 10%.

Find out more about the pros and cons of underfloor heating in our practical guide 

5. Energy-efficient windows and doors

You could be losing 15-20% of your home’s heat through your windows and doors. Double or even triple glazing will help reduce heat loss dramatically. And even if you don’t want to fully replace your existing windows and doors, there are a few clever fixes you can do to help.

Find out more in our complete guide to energy-efficient windows and doors

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The best home insulation materials

From sheep’s wool to paper, foil, polystyrene and polyurethane spray foam, good insulators come in various forms. Most work by trapping tiny pockets of air within them – and the most commonly used are mineral and glass wools, which come in a roll, as a blanket, or as a type of batt or slab.

How much can home insulation help you save on bills?

While insulation costs can really vary (depending on what you’re having done), you could save as much as £250 per year on your energy bills4 – and much of what you can do will pay for itself within 2 to 5 years.

One of the other cheapest ways to reduce heat loss is by draught-proofing – and payback is fast with this one, so it makes even more sense if you’re renting. Read more about draught-proofing in our blog on reducing your energy bills.

Plus, home insulation can do more than just help you save money on energy – it can also help you save the planet. With the UK committed to reducing its greenhouse gas emissions by at least 80% before 2050 (relative to 1990 levels), home insulation can play a big role. That’s because the energy used in UK homes makes up about 20% of our greenhouse gas emissions – and three-quarters of that comes from heating and hot water alone. 

With a recent report finding that better home insulation is the key to lowering UK carbon emissions, it’s clear that retro-fitting existing homes with better insulation can have a huge impact on our efforts to lower our carbon footprint.

Make your home more cosy with financial help from the Green Homes Grant

The UK government recently announced the launch of Green Homes Grant. It’s part of their effort to help reduce carbon emissions and help cut energy bills.

The vouchers are worth up to two-thirds of the cost of making your home more energy-efficient, up to a maximum of £5,000 for most households. You’ll be able to spend them on a myriad of improvements, including:

A whopping £2bn has been put aside for the grant, which is designed to help the government meet its targets for job creation and cutting carbon emissions.

Find out more about the Green Homes Grant Scheme and how to take part 

Home Insulation work and planning permission

Most of the time, you won’t need planning permission before carrying out insulation work. But if you’re doing external wall insulation, or if you’re planning glazing work in areas where there are conservation schemes, you should check with your local council’s building control department first.

Even when you don’t need planning permission, other building regulations could still apply. So it’s always a good idea to check. 

How switching supplier can also help cut your bills

Finally, you could save on bills by moving to a new supplier. And if they’re investing in new technologies that can lower bills and reduce the impact on our world, even better! 

If you’re thinking about switching to OVO, Better Smart is our lowest rate plan, and it’s designed for new members who don't yet have a smart meter. 

See how much you could save - get a quote

Sources and references

Based on insulating a gas-heated detached home. The installation costs are unsubsidised averages and will vary.