Home insulation - the basics

The Energy Performance Certificate (EPC) rates a property on a scale from A (very efficient) to G (inefficient). An EPC is required whenever a property is built, sold or rented, though many older properties don’t have an EPC rating. The UK’s housing stock is amongst the least efficient in Europe with an average rating of EPC D. Older properties (pre 1930) tend to be the least energy efficient.

Heat from your house is lost in roughly the following proportions: walls 40%; the roof 25%; windows and doors 20% and the floor 15%.

Every home is different so there isn’t a standard formula for insulation. For example, there is a big difference between the insulation required on detached houses versus flats or maisonettes. Also walls can be either cavity walls (there is a gap between the inner and outer layers and an insulator is inserted into the gap) or solid walls (internal and external insulation can be applied but this can be disruptive). Roofs can be insulated immediately under the roof or above the ceiling. Double glazing and draft protection can be applied to windows and doors. Floor insulation can also be possible though often floor coverings can be a simpler option.

It makes sense for everyone to review their insulation as it can save money, keep you warmer and reduce the amount of energy you are using. The problem however is that to do this properly is very expensive. It is estimated that to retrofit UK housing stock could cost up to £40 billion and would cost between £5k and £20k per property and even then all properties wouldn’t meet the highest EPC rating..

Another problem is that care needs to be taken with insulation or there is a risk of creating issues such as damp, mould and condensation if the work is not carried out to the right quality. There is a standard called PAS 2035 which outlines how retrofit projects should be managed and delivered. Work done to this standard will be of high quality but will be more expensive than work done to building regulation standards.

If your property has a low EPC rating it should be possible in most cases to make significant improvements by installing some form of insulation. If there are grants or schemes available you should look out for them and try and find out what practical or cost effective options you have got to improve your energy efficiency.