More education needed around ventilation

Thermal efficiency targets are front and centre of retrofit projects to improve the sustainability of the UK’s housing stock. Ben Robinson, Technical Manager at Alsecco looks at how to ensure ventilation remains effective when improving external wall insulation. 

With the Government setting a target to bring all energy poor homes up to an EPC energy rating of C by 2030 in support of its drive to reach net zero by 2050, insulation will play a key role in achieving these ambitious goals.  

However, it is important that ventilation is considered at all stages of an insulation upgrade – and that the importance of ventilation is clearly communicated to homeowners and occupants to avoid trapped moisture becoming a problem. Education of the whole supply chain, from specifier to contractor and homeowner, is central to that if we are going to raise awareness of the fact that homes will always need to breathe. 

An estimated 35% of thermal loss occurs through walls, which makes insulation a priority in addressing energy emissions generated through heating a home. Ventilation – and the potential for damp – must be a key consideration from the start of an insulation upgrade project. Poor insulation can be a cause of condensation, leading to the formation of mould and mildew as cold walls foster damp conditions, which can lead to serious health problems for occupants if allowed to continue.  

Improving external wall insulation is a solution to this problem which, at the same time, can also improve the overall thermal efficiency of the home itself. However, care must be taken to achieve the right balance so that air and moisture still has an outlet to ensure optimal living conditions, as changing the fabric of a structure will also fundamentally change how it operates.   

Technical competency in the specification and installation of the external wall insulation is essential, alongside careful collaboration with specifiers, architects and principal designers. A good quality installation will ensure the temperature of the wall remains stable, while shutting out moisture and interacting with other retrofit measures in a complimentary manner.  

This work also needs to be underpinned by competent installation. Gaps must be avoided to stop moisture and heat loss affecting walls, including where insulation boards join together, for example. In addition, any thermal bridging should be mitigated to avoid pockets of cool air condensing within insulation gaps and voids, or where different materials have been used, or pipework or soffits pass through the insulation. Taking care to avoid these gaps, or sealing them, will help to avoid the problems thermal bridging can cause. Any potential issues in the building should be flagged up at the earliest stages with a condensation risk analysis, which can then be incorporated into the build.  

Where external wall insulation is being upgraded, the main contractor should always check there is adequate ventilation in place, such as trickle vents on the windows and extractor fans in bathrooms and any room subject to moisture release. There also needs to be a shift in approach to highlight the importance of ventilation and that increased insulation will demand greater consideration of this from homeowners.  

In making changes to support a better future, it is essential to ensure best practice to support optimal living conditions into the future.  

alsecco.co.uk