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How can external wall insulation reduce energy usage?

When you are thinking about reducing your energy usage a good place to start is making sure that your home is as energy efficient as possible. In the UK about 35% of heat loss is through external walls and so wall insulation plays a huge role in the energy efficiency of your home as a whole.

External wall insulation will reduce this heat loss meaning that you need to use less energy to keep your home warm, the energy saving trust estimates that the average detached UK home with external wall insulation saves around £460 annually.


In older homes (pre 1920s) this presents a special challenge because many are built with a single solid wall, notoriously bad for heat loss. Single solid walls can up to double the amount of heat loss you will lose, by using external wall insulation on single solid walls you can reduce this effect significantly.

The external wall insulation is fitted to the outside of your house and then a decorative finish is rendered on top, it will have the added benefits of protecting the walls by filling in cracks, give your house extra weatherproofing and increase the sounds resistance of the walls.

Is my house Solid Wall?

If you are not sure whether or not your house has single solid walls and whether you could benefit from external wall insulation there are a number of ways to tell.

Have a look at the pattern of the bricks, if the bricks are all oblong and laid end to end it is likely that the wall has a cavity whereas if some of the bricks have the square end facing it is likely that the wall is solid. Stone walls are also almost always solid. Your house is likely to have a cavity if the walls are more than 260mm thick.


Green Deal Home Improvement Fund:

  • up to £4000 for installing solid wall insulation

More people will get help to improve the energy efficiency of their homes through a new release of the Green Deal Home Improvement Fund (GDHIF).

“This fund is a big success story for the Green Deal – helping thousands of people improve their homes so that they’re warmer, greener and cheaper to run.

“The best way people can cut their energy bills, this winter and every winter, is to improve their homes so that they leak less heat and use less energy. That’s why we’ve increased the funding available for the Green Deal to help even more people start saving money sooner.”