Cavity wall insulation - what is it and how much can I save?   

About 1/3 of heat lost in an uninsulated house goes through the walls. If your house was constructed 20 years ago or earlier, it is likely that its walls are of cavity wall type which means the outer side is made up of 2 layers with a small clearance between the layers. So, applying insulation to your cavity walls is the most effective solution to prevent further heat loss from your home.

What is cavity wall insulation?

Cavity wall insulation is a process in which the empty space between layers of a cavity wall is filled with a porous substance. Heat loss is greatly reduced by merging the still air inside the cavity wall with the insulating substance.

There are various types of insulating substances. For new buildings that utilize cavity type walls, the most popular “insulators” are rock wool panels or glass fibers. For existing buildings with cavity walls, glass wool or cellulose fiber is widely used. Holes are drilled in the walls and the insulating substance is blown through these holes until every empty space in the cavity wall is filled up.

Aside from reducing heat loss, cavity wall insulation can also provide a steady temperature level in your entire house, and can also keep the interior of your house cooler throughout the summer months.

In physics, warm air will always find its way towards an area where the air is colder. Why? Because the pressure around the colder air is much lesser than the pressure in the warmer air, thus making the warmer air go in the area of the cold air – to even the pressure. So it goes that during winter the warm air inside your house will escape through the ceiling and walls.

The purpose of cavity wall insulation is to minimize the escape of warm air and keeps it inside your house for longer period. It works by filling the cavity with a substance that has plenty of air pockets. When the cavities are all filled up, heat cannot easily escape and likewise cold cannot get in that easy.

How much money could you save?

Supposing you have a house with 3 bedrooms and your heating system uses gas for fuel, by installing cavity wall insulation you could save as much as £110 per year from your heating costs because when your cavity walls are properly insulated heat loss can be prevented by up to 35%.

The average installation cost is about £500 for cavity wall insulation. But the major energy providers are offering subsidy, and if take advantage of it, you will only shell out around £250, that is half the cost of an unsubsidized installation. There are also grants that are made available and funded to help those who wish to install wall insulation. You can search online to check what is available.

With savings of £110 per year, the installation cost will be recovered in about 2 years. Keep in mind that higher savings can be achieved by having the proper insulation installed in your house and because you will need less energy to keep the indoors warm, this will translate into bigger savings.

Aside from saving money from heating costs, you will also help fight the global problem of climate change. By reducing your energy consumption, the CO2 produced by your home will also be reduced. That will be around 550 kg less CO2 per year.

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