Insulation

What you need to know

Many organisations recommend improving the energy efficiency of homes through a fabric-first approach. This means making sure that a home is well insulated before looking to install other efficiency measures. This is because an insulated home will retain energy more effectively than a home that has not been insulated at all, reducing how much energy you need to spend on keeping your home warm.

How it works

Insulation is the process of filling in spaces in houses where heat and energy are often lost. Insulation works by using specialised materials such as foam, beads or fabric. These materials are non-conductive, which means that they do not transfer heat easily. By using these materials to fill in cold spots within your house, heat from your radiators is kept inside the home, meaning you spend less on your energy bills.

Where insulation is installed

There are 4 main ways through which a home leaks heat. They are through the: 

• walls
• loft
• floor
• windows

For each of these issues, there are a range of options for how you can insulate. If you want to know more, we’ve detailed each set of options below.

Insulating your walls

On average, a house will lose around 35% to 45% of its heat through uninsulated walls. This makes our walls a massive target for improving the energy efficiency of our homes. The type of insulation you will need to have installed will depend on the type of walls you have in your property.

Solid wall properties

If your home was built before approximately 1920, your house is likely a solid wall property. This means that the gap between inside your home and outside your home is occupied by one solid layer of bricks. To insulate these properties, you need to apply a layer of insulating material either inside or outside your home. These options are called Internal Wall Insulation (IWI) and External Wall Insulation (EWI).

EWI works by fixing a layer of insulating material, such as polystyrene foam or mineral wool, over the external walls of your home. This material is then covered with a protective covering, also known as a render or cladding, to protect it from the weather and ensure it does not spoil how your house looks. EWI can be expensive, typically around £10,000 for a standard property, but it has many advantages. The installation is unintrusive, meaning you can keep living life without interruption.

EWI can provide an extra layer of external protection against strong weather, the protective cladding can make your home look better, too.

For some properties, EWI may not be possible. This could be due to personal preference, planning permission, or the condition of the walls. IWI is an alternative solution. With IWI, thinner rolls of insulation are installed over the internal walls of your home. IWI can be cheaper, and may suit certain homes better than EWI, however the installation process can be a lot more disruptive and will slightly reduce the size of your rooms.

Cavity wall properties

For most properties built after 1920, your home may be built from cavity walls. Unlike solid-wall properties, cavity walls are made from two layers of bricks with a gap between them. To help reduce heat loss from cavity walls, many people choose to have cavity wall insulation (CWI) installed in their properties.

Cavity wall insulation is different to solid wall insulation. In CWI, the installer will fill the cavities with an insulating material by pumping it through the wall to combine with the air inside the cavity and protect against heat loss. There are multiple different insulating materials, however most CWI is installed using polystyrene beads or mineral wool. CWI has multiple advantages. Installation is often quick and non-disruptive, as many installations only require small holes to be drilled into your walls that will be filled up after installation.

It’s often a lot cheaper than solid wall insulation; most CWI installations cost between £1,000 to £3,000 depending on the size of your property.

Alternative walls

If the walls of your home are made from a different material, such as steel or concrete, you may need a different form of insulation for your property. If you think this might describe your situation, it is recommended you contact a specialist installer with experience in insulating your building type to advise you on the best steps.

Insulating your loft

Insulating your loft is one of the most effective ways to increase the energy efficiency of your property and save money on your energy bills. If your home currently has no loft insulation, you could save up to £250 on your annual energy bill depending how your home is built.

Loft insulation is often quicker to install than wall insulation and can be suitable for a wide range of homes. If your loft is accessible, with no condensation or damp problems, an installer will be able to insulate by simply installing a layer of mineral wool to cover the loft space while leaving room for ventilation around the eaves.

If your loft is not accessible, or very difficult to access, an installer can blow insulating material into your loft space. This will require specialist equipment and knowledge from an appropriate installer.

Insulating your floors

Insulating your floors can often be done by yourself, or by an installer if you do not feel confident. Sealant can be used to fill any gaps between your floorboards where draughts escape. Alternatively, an installer can lay mineral wool insulating material underneath your floorboards. This may be slightly disruptive during the installation process but can reduce heat lost to draughts and gaps beneath the floorboards.

Insulating your windows

Older properties can lose a surprising amount of heat through old, single-glazed windows. This is when a window is made up from a single sheet of glass sealed into the window frames.

The most common solution to this problem is to install double or triple-glazed windows throughout your property. This is when your windows are made up of 2 to 3 panes of glass with layers of air between them. The gaps between panes help slow down and reduce heat loss through windows and can be an effective way to prevent wasting energy on heating your home. They can also reduce condensation and protect against noise.