Party Wall Insulation

Party Wall Infographic CTAParty wall insulation is now included in RdSAP 9.92 which is the current software used to carry out energy calculations for existing homes.

The inclusion comes following research headed by Leeds Beckett University (formerly Leeds Metropolitan University), MIMA (the Mineral Wool Insulation Manufacturers’ Association) and Knauf Insulation, which found that a significant amount of heat is lost through uninsulated cavity party walls.

We are now able to share the technical knowledge and experience we have gained from the research programme which began in 2005. Our Supafil Party Wall solution has been developed specifically for the insulation of party cavity walls to prevent heat loss through party wall thermal bypass.

What is Party Wall Thermal Bypass?

Heat lost through an external wall is mainly due to conduction through the wall as the heat passes through the various material layers, whereas heat loss through party walls is due to a phenomenon called "party wall thermal bypass".

Party Wall Bypass is a mechanism of heat loss that is driven overwhelmingly by bulk air transfer to and from the party wall cavity.

Party wall thermal bypass occurs where cold air enters the uninsulated cavity at exposed edges. The cavity creates a chimney effect and the cold air rises as it is heated by heat conducted through the party wall from the adjoining homes. The heated air then escapes from the cavity to the external environment – either into the loft space or through the roof.

How much heat is lost through an uninsulated party wall?

The research we carried out in conjunction with Leeds Metropolitan University and MIMA showed that there is a huge amount of heat lost through uninsulated party walls. Indeed, the study showed that in modern houses the heat loss into the party cavity walls could be as much as the total from all other elements.

The amount of heat lost through party wall bypass will differ based on the energy efficiency of the home. RdSAP will provide an individual calculation for each home.

Modelling on standard homes shows that the saving on energy bills using current energy prices could be up to £70 per year.

When aggregated across all affected homes in the UK this equates to an estimated £465 million per year.

How many homes are affected?

There are approximately 5 million homes which are losing money due to uninsulated party cavity walls. Homes built post 1945 are generally built with a cavity party wall and these are currently uninsulated.

A study carried out by BRE (Building Research Establishment) estimates that if all of the 5 million homes were insulated, it would save approximately £465 million per year – equivalent to a total of £19.5 billion over the life of the measure.

How can Knauf Insulation help?

Following our involvement in the research programme, we have gathered valuable experience covering both surveying and installation methods.

To identify affected homes, we have worked with partners to develop a methodology which includes a combination of stock profiling, ageing and visual checks.

Our Supafil Party Wall solution has been used and proven to prevent party wall thermal bypass whilst not adversely affecting the acoustic performance of the party wall.

Supafil Party Wall is installed by approved installing technicians and we have a national network to provide a solution no matter where you are located.

Contact us to learn how we can help you to identify affected homes and to help provide a solution to stop party wall thermal bypass.