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Does my home have solid or cavity walls?


Solid walls are often found in homes built before the 1920’s and typically cavity walls are found in homes built after the 1920’s. The brick work on your property can give you an idea of the type of walls you have; if the bricks are all facing sideways, it is likely you have cavity walls. If you are not sure, a surveyor will be able to advise you.

You may be able to tell if your home has had cavity wall insulation by looking for small holes that have been filled in where the insulation was injected through – these will often be just under the windows.

Solid wall insulation

Solid walls have no cavity, therefore, more heat is able to escape. Solid walls can be insulated both internally and externally to slow down the rate of heat loss. It should be noted that these measures can be costly and may cause disruption. This said, insulating solid walls can create big savings on your energy bills and keep your home much warmer.

External insulation involves fixing a layer of insulating material to the outside walls. For this reason, you may need to get planning permission to install the insulation. Depending on the size of your home, external wall insulation can cost between £8,000-£22,000, but could save you around £255 a year on your heating bills for a typical semi-detached house.

Internal insulation involves fixing insulation boards to the interior of the property, again, helping to reduce the amount of heat lost through your walls and therefore, reducing your bills. Internal wall insulation can be cheaper than external wall insulation; however, a lot of disruption may be experienced during the installation process. Typically, internally insulating your home will cost between £4,000 and £13,000, depending on the size of your home, but an average semi-detached house could save around £255 per year on heating costs. For more information on the savings you can make visit the Energy Saving Trust’s website.

Cavity wall insulation

If your house has a cavity, your external walls will be made of two layers with a gap in between them. Cavity wall insulation fills this gap, reducing the amount of heat lost through the walls. Newer homes will have cavity wall insulation installed as part of the building process. The insulation can be made of various materials and is injected into the cavity through holes drilled into the outer walls, which are then filled in. Cavity wall insulation can typically cost around £500 but can save you around £100 on your energy bills annually, making the pay back time for this technology sometimes less than 5 years. You can find out more information about cavity wall insulation on the Energy Saving Trust’s website.

Roof and loft insulation

Loft insulation is one the most simple yet effective ways to reduce heat loss in the home. In an uninsulated home, a quarter of your heat can be lost through the roof. Depending on if you do the work yourself or get professional installers to do the work for you, loft insulation can cost between £300-£400 but can save you around £100-£200 a year on your heating bills. Furthermore, loft insulation can last around 40 years so will pay for itself several times over.

It is always worth asking your supplier if they are able to subsidise any of these insulation measures. Some energy companies are obligated to fund insulation and heating measures to help vulnerable and low income households. More information about the different savings can be found on the Energy Saving Trust’s website.

Solar panels (electricity from sunlight)

Also known as photovoltaic (PV) panels, solar panels capture direct sunlight to generate electricity.

You may need to alter how you use your electricity to make the most of your solar panels. Any energy your solar panels generate can either be used to run your appliances for free or, if it is not used, exported back to the grid. If you use more electricity than your solar panels are generating, you will need to buy energy from the grid. Therefore it is worth turning on high powered appliances in the middle of the day when there is most sunlight. For this reason it is also worth staggering the use of high powered appliances. To find out if your home and heating system are suitable for this technology visit the Energy Saving Trust’s website. You may need to get planning permission to fit these panels.

Solar water heating (solar thermal)

This technology uses heat from the sun to warm hot water. Used alongside conventional boilers or immersion heaters, the water will be pre-warmed by the sun, so less energy is required to bring the water up to a suitable temperature. Solar hot water is a green, renewable heating system which could reduce the cost of heating water in your home. Visit the Energy Saving Trust’s website to find out if your home and heating system are suitable for this technology. You may also need to check if planning permission is required for these panels.

Air or ground source heat pump

These absorb heat from either the outside air or the ground to heat radiators, underfloor heating, warm air heating systems and to provide hot water in the home. They use some electricity to run so you will still have to pay fuel bills. Heat pumps are effective and can help lower your bills, particularly if you are using them to replace an electric heating system and your home is well insulated. You may need planning permission for this technology. For more information on using and installing heat pumps visit The Energy Saving Trust’s heat pump webpages.

Wood fuel heating (biomass)

Wood-fuelled heating systems burn wood pellets or logs and can be used to fuel a central heating system boiler, or to heat a single room by a stove. Water can also be heated using biomass using a back boiler with a stove. For more information visit the Energy Saving Trust’s website.

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