Cavity walls are present on the majority of brick-built houses dating from the early 20th century or later. Since warm air can be trapped in the space inside a cavity wall, forming an additional barrier between the inside and outside, these make buildings better at keeping heat in and save on energy bills, especially when insulating materials are fitted in the cavity.
Typically, the process of insulating a cavity wall would start by confirming that the structure of the wall allows for it. A hole would usually be drilled in the outside wall to access the cavity, and from there insulation materials such as wool or foam can be injected into the space. As long as appropriate ventilation is also fitted, this simple process is enough to significantly improve the energy efficiency of many homes in a safe and cost-effective way.
Tip: You can actually distinguish them by the pattern of the bricks from the outside in a lot of cases. If all the bricks look the same size and are arranged facing the same way, there is most likely a cavity between two layers of the wall. If the bricks alternate in size and shape, this means the wall is probably one solid construction and there is no cavity area.
Once you’ve established that your walls have the capacity to be insulated from the inside, the next question is whether this can be done for free. Depending on a few factors, you may be entitled to this under the government’s ECO (Energy Company Obligations) scheme. Usually your entitlement to free cavity wall insulation will depend on things like your household income, whether you have children living with you, if you are disabled, any benefits you and receive and various other factors.
If you quality, free cavity wall insulation (and in some cases loft insulation) can be provided by your energy supplier. Different energy companies will have various requirements for eligibility which can vary, so you are advised to check with the company that provides your utilities. Often they have online tools and resources to help you find out if you actually qualify.
Using the same tools, you may also be able to estimate the total saving on your energy bills based on getting the insulation. Typically this cost saving could run into the hundreds of pounds per year, so even if you can’t get cavity wall insulation for free, you are usually advised to pay for it if you can afford to.