Compare loft and cavity wall insulation

  • You could reduce your energy bill by up to £390/year*
  • Insulate your loft for as little as £149
  • Cavity wall insulation for as little as £149

Home insulation could enable you to save energy and reduce your energy bill by up to £390/year*. A typical house can lose half of the heat through the walls and loft. If your house has a cavity wall, but no insulation, you could benefit from installing cavity wall insulation. Similarly the recommended level of loft insulation is 270mm; if you have less than 160mm, you would benefit from insulating your loft to prevent heat loss through your roof.

Home insulation offers from the big energy suppliers

Supplier Cavity wall Standard loft
(less than 60m existing)
Top-up loft
(more than 60mm existing)
Npower from £149 (1) (price may vary) from £149 (1) (price may vary) from £149 (1) (price may vary) Please contact the
supplier directly
British Gas from £199 (1) (price may vary) from £199 (1) (price may vary) from £199 (1) (price may vary) Please contact the
supplier directly
EDF Energy £199 (2) (price may vary) £199 (2) (price may vary) £199 (2) (price may vary) Please contact the
supplier directly

Priority groups include people receiving certain benefits, such as housing benefit and income support. Please check for details with the supplier or on the application forms to see if you qualify for free or reduced prices.

Cavity Wall Insulation

Cavity wall insulation

Generally, homes built between 1930 and 1995 have empty cavity walls. Cavity wall insulation simply involves filling the cavity with an insulating material, usually by drilling small holes in the wall and injecting the insulating material until the cavity is filled. Depending on the size of your home this process usually takes around 2-3 hours.

Costs can be as low as £149 (or free if you qualify) and you can save you up to £270 on your energy bills.

Loft Insulation

Loft insulation

Loft insultation is an effective way to save energy and money on your energy bills and can cost as little as £149 (or free if you qualify). The current recommended level of loft insulation is 270mm (10.5"). If you have less than this or if you have no loft insulation at all you can benefit by losing less heat through your roof.

Insulating your loft, simply involves laying rolls of mineral wool fibre (or some other insulating material) between and across the joists in your roof space and the work usually takes around 1-2 hours depending on the size of your property.

Apply for Home Insulation

All of the big domestic energy suppliers provide solutions for reducing energy consumption as part of the Carbon Emissions Reduction Target (CERT). Please use the apply links in the comparison table to apply online, where no apply button is available you will need to contact the supplier directly.

(1) Prices are based on an average sized three-bedroom semi-detached home. Eligible only for measures recommended by the appointed surveyor. Prices may vary and are subject to change and exclude any scaffolding and specialist equipment if required. Discount on standard prices as at August 2010 on both loft and cavity wall insulation. This offer cannot be used in conjunction with any other British Gas insulation offer.

(2) This offer is available for all heating fuel types. These prices and the free insulation offer apply to standard properties with up to 4 bedrooms. Additional costs will apply to large /non standard properties. You will be advised of any extra costs for additional areas at the time of survey which should be based on a standard rate of £5.00 per m2 inc. VAT. All boarded walkways in lofts are charged extra. If you receive income or disability related benefits, or are aged 70 or over, you may qualify for work to be carried out free of charge. Offer is subject to a site survey. All information is correct at time of going to print, but subject to change

*£390 savings a year figure is for 1940's 3 bed semi detached home with a ten year old gas boiler and a gas price of 3.73p/kWh, when cavity wall insulation and loft insulation are installed. More modern homes save less. Individual savings depend on a large number of factors and the £390 quoted should be treated as a guide.

More on cavity wall insulation

Most conventional housing built after 1920 is of brick cavity wall construction. This means that the outer walls are made up of two-brick construction, with an air gap in between them.

This unfilled air gap between the two walls can mean that any heat escapes easily through the walls and into the outdoors, meaning that a large proportion of the heat you use to warm your home is being lost to the great outdoors.

Cavity wall insulation is designed to effectively fill this gap with an insulating material, and is injected into the cavity from the outside of the building. This helps to reduce the amount of heat escaping through the walls, so your house heats up quicker and you can reduce your energy consumption accordingly.

What are the environmental and cost benefits of cavity wall insulation?

Cavity wall insulation is an efficient way to significantly reduce the amount of energy you need to heat your home, while also reducing carbon emissions. The average house could reduce heating costs by a third by installing cavity wall insulation.

Between 2002 and 2005, around 800,000 UK households installed cavity wall insulation, saving a combined estimated total of 400,000 tonnes in CO2 emissions. In fact, if all the houses in the UK with unfilled cavity walls had them filled, the energy saved could heat 1.7 million homes each year.

What is the installation process for cavity wall insulation?

It takes typically as little as two to three hours to insulate a three-bed semi-detached house – and it can cost under £500. The typical payback period for having cavity wall insulation is about three years, so you can make up for the initial installation cost quite quickly and then continue reaping the benefits of significantly lower energy bills.

Insulating hot water tanks and pipes

Fitting a British Standard "jacket" to insulate your hot water cylinder can cut heat loss in your home by around 75%. These jackets work by reducing the amount of heat that escapes from the cylinder, effectively ‘trapping’ it in; ensuring that you spend less money heating up your water and that when you do use hot water, it stays hotter for longer.

These jackets can be found in most DIY stores, and are cheap to buy and easy to fit. If you already have a jacket fitted to your hot water cylinder, check that it's at least 75mm (3") thick (the thickness recommend by the Energy Savings Trust). If your jacket doesn’t meet this thickness, it’s a good idea to replace it with a suitable one to ensure you’re saving as much heat as possible.

Hot water pipe insulation works in a very similar way to the hot water cylinder jacket, using insulation to reduce the amount of heat that escapes from the exposed hot water pipes in your home. Installation is easy for the accessible pipes, but you may want to consult a professional for the harder to reach ones.

The table below demonstrates how much it could cost you to carry out these fittings, as well as how much you could save and how much time it will take before the fitting costs are entirely recovered:

Fitting a jacket to your hot water tank Insulating hot water pipes
Cost of fitting (DIY) from £10 from £10
Annual saving on fuel bills around £20 around £10
Time for costs to be recovered around 6 months 1 year

Draught proofing

Hold the palm of your hand up against the windows in your home. If you feel cold air coming through at all, even just a little; this means that warm air is escaping. In fact, in a typical home, 20 per cent of all heat loss is due to ventilation and draughts.

Draught proofing is an easy, cost-effective way to reduce heating bills, and most of the materials needed to draught proof your home are readily available from DIY stores.

If you decide to source your own draught proofing materials, you should take due care and consideration when choosing them. The quality of the products will affect their performance and durability over time, meaning that cheaper options may deteriorate and need to be replaced – so you should check that all materials conform to the BS 7386 standard.

There are several types of materials available - from brushes, foams and sealants to strips and shaped rubber or plastic.

There are some other things you could think about when insulating your home:

  • Adequate ventilation is as important as draught proofing - and essential if you have solid fuel fires, gas fires or a boiler with an open flue
  • Ventilation is especially important in kitchens and bathrooms
  • Draught proof internal doors, if needed, but leave kitchen and bathroom windows alone to keep condensation under control (If condensation is a problem, an extractor fan will help)
  • Open a window while cooking, running hot water or drying clothes
  • Trickle vents in the window frame provide background ventilation - not usually enough on their own, but they reduce the need to open windows
  • If you have chimneys, sweep them regularly and check air bricks for blockages.

What are typical draught-proofing costs?

Job Cost
Cost of fitting (installer) from £75
Cost of fitting (DIY) from £50
Annual saving on fuel bills around £20
Costs recovered (installer) around 4 years
Costs recovered (DIY) 3-5 years

How to lower your energy bills even more

Insulating various fixtures and fittings which output heat in your home can be an incredibly efficient way to reduce your heat loss, and thus your energy bills in the long term. However, there is also one very simple way you can reduce your heating bills – and you don’t even have to leave the comfort of your sofa to do it.

It’s possible that you are currently over-paying for your gas simply because you aren’t on the cheapest possible tariff for your energy supply. To find out of this is the case, compare energy deals with UKPower and switch energy supplier in minutes.

How to switch energy supplier

How to switch energy supplier with UKPower. Simply enter your postcode and we'll compare energy prices from a range of suppliers. You then choose the one you prefer and we'll take care of the rest.