What is Insulation and How Does it Work?

Home insulation is when you protect or cover areas in your home to stop heat from escaping or entering.

08 Oct 2020 | Make my home greener

Home insulation infographic showing where heat escapes from a house. Can't see the image? Read what it says: https://www.edfenergy.com/sites/default/files/insulation_homepage_illustration.pdf

What areas are best to insulate?

Floors, lofts, pipes, windows and walls are the main areas where hot air will escape and cold air can come in.

There are many simple yet effective ways to insulate your home, which can significantly reduce the amount of heat you waste whilst lowering your heating bills.

Explore how this can be done in every part of your house below.

Why should I insulate?

Insulating your house means you’ll keep warm air in and cold air out. Not only will your home be cosier, it will save you money on your bills and help you avoid draughts, damp or mould. If left untreated, damp and mould can lead to health problems such as respiratory symptoms, respiratory infections, allergic rhinitis and asthma.

Some of the other benefits include:

  • Less heat loss - Heat rises, so insulating your house properly means you keep more heat inside the house.
  • Save money - You'll keep more heat inside your home with roof insulation – reducing the amount of energy you use and your bill.
  • Quick to install - Loft or attic insulation is easy to install and causes minimal disruption to your home.
  • Maintenance free - It's maintenance-free once installed.

Help Britain Achieve Net Zero

Nearly two thirds of UK homes fail to meet long-term energy efficiency targets, according to data analysed by the BBC. More than 12 million homes fall below the C grade on Energy Performance Certificates (EPCs) graded from A-G.

It means householders spend more on energy bills and pump tonnes more CO2 into the atmosphere than necessary. The government has said it needs to go "much further and faster" to improve the energy performance of homes to help Great Britain meet its 2050 net zero carbon target, which was signed into law in June 2019.

fibreglass loft insulation roll in attic

Roof and loft insulaiton

Installing loft insulation is as simple as unrolling a rug. A mineral fibre material is laid between the joists and then over the joists in your loft or roof. This thick material captures heat normally lost through the roof and stops draughts getting in.

If you already have loft insulation, you could still benefit from a top-up. If your insulation is 100mm or less, you can increase it to the recommended level of 270mm.

Cavity wall insulation cross section

Cavity wall insulation

To start we need to find out if your home is suitable for cavity wall insulation. To assess this we drill small holes in your outside walls. If it's suitable for your property, the cavity between the inner and outer walls is then filled with insulating material. The holes in the brickwork are then filled in again. Installation process takes just a few hours and should come with a Cavity Insulation Guarantee Agency (CIGA) guarantee.

See if we can help you save energy with subsidised energy efficiency measures from the government's ECO scheme.

floor insulation under concrete

Floor insulation

According to the Energy Saving Trust you could save up to £40 a year on heating costs if you have well insulated floors.

You can insulate your floors either by laying down new insulation, or by sealing draughts and gaps. You can use a sealant from a hardware store to seal up gaps but if you need proper under floor insulation, first you need to work out what kind of floor you have.

House after insulation fitted
House before insulation fitted

Solid wall insulation

Solid wall insulation keeps older homes warmer for longer. This can transform the look of your property and stop heat loss – it's like wrapping a huge blanket around your home. Solid wall installation normally takes between 2-4 weeks and can be done with very little disruption because no interior work is needed.

copper pipe foam insulation

Pipe insulation

Pipe insulation is when you cover your pipes with foam tubes or a reflective wrapping. It's a great idea to insulate any exposed pipes leading from your tank to your boiler to keep the heat in.

Foam covers keep your pipes snug – and therefore they lose less heat. You can get different shapes and sizes from any hardware shop and they're usually a cheap option for keeping that extra bit of heat in.

a man uses a glue-gun like apparatus to put draught proofing paste onto a window sill


Draught insulation is a cheap and effective way to save you energy and money by stopping heat escaping from your home. By blocking any gaps where heat can escape and cold air can get in, you'll keep your home temperature just right all year round.

Making sure your home has door insulation and window insulation means you keep the cold air from entering your home and the warm air from escaping. These can all be blocked up with different kinds of draught excluders. There's lots to choose from.

It's really important not to block any deliberately placed ventilation points – such as extractor fans, grilles or wall vents.

Insulating tanks

Lagging water tanks and pipes and insulating behind radiators reduces the amount of heat lost, so you spend less money heating water up, and hot water stays hotter for longer. Insulating your hot water cylinder is one of the easiest ways to save energy and, therefore, money.

If you already have a jacket fitted around your tank, check the thickness. It should be at least 80mm thick; if it isn’t, consider buying a new one.

Upgrading your hot water tank insulation from 25mm to 80mm thick, using a British Standard jacket, could save you around £20 a year, which is more than the cost of the jacket.

Slipping pipe insulation around your exposed hot water pipes will keep your hot water hotter for longer.

Insulation to pipes is easy if the pipes are accessible; if your pipes are hard to reach, you may need to engage a professional.

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