Cavity Wall Insulation
Circa 35% of heat is lost through external walls.
Prior to the 1920's, homes were built with solid walls. During the 1920's, they were built using walls with a cavity. The separation of the two layers of brickwork gave two advantages.
Firstly, where homes were located in areas of driven rain, the separation of the two walls prevented water passing through the wall, which could occur with solid walls. Secondly, the trapped air within the cavity gave a degree of thermal insulation.
All homes constructed since the 1983 will have a degree of applied cavity insulation.
Your uninsulated cavities can be insulated using various products. The most common are foam (which can be pumped in), mineral fibres and polystyrene beads (both of these are usually blown in).
Cavity wall insulation should not be inserted in the cavity in areas of driven rain, as damp patches can occur, resulting in future maintenance costs. External or internal wall insulation should be considered in these areas.
Typical costs are in the region of £100-£350 (including energy supplier subsidy), giving annual savings up to £135. The payback period is up to 3 years, with annual carbon savings of 550kg*.
If you would like to view the blog on the green conversion and renovation of a Victorian London apartment, click here.
*Energy Saving Trust 2011.