Schools constructed from masonry and built after 1920 are most likely to have cavity walls but it was not until after about 2005 that it became compulsory for these cavities to be insulated. Insulating cavity walls can reduce heat loss through the walls by a factor of two, reducing the cost of heating the whole building by up to 30%.

Cavity wall insulation typically costs about £20/m2 of wall area, and payback on the investment through energy savings is between 3 and 10 years. It is probably one of the most cost effective ways of reducing your heating bills.

If your school’s buildings were built between 1920 and 2005, it is worth finding out whether the walls have cavities and whether they have been insulated. If they have been insulated post-construction, you can sometimes see tell-tale signs of small 2cm holes at approximately one metre intervals which are filled in with a different colour mortar. It is often easier to ask a contractor to visit the school to provide a quote as they will be able to tell you whether walls have been insulated, often using a mini video camera which they push into the cavity.

Visit the Insulation Assurance Authority (IAA) website to find a local contractor who will do a survey to tell you whether your school’s cavities can be insulated and provide you with a quote. IAA members should be part of an insurance scheme, like CIGA which provides 25 year guarantees. There are two main types of insulation, blown fibre and polystyrene beads. Each type has their pros and cons. Appointing an installer who can provide both types should ensure that you have the most suitable type installed for your walls. We generally advise using ‘carbon’ polystyrene beads as they provide better insulation, distribute in the cavity better and are less likely to ‘slump’ over time.