Effective from the 1st July 2012, all in-situ formed insulation products certified by the British Board of Agrement (BBA) need to have thermal conductivity values declared to the Lambda 90/90 convention.
Knauf Insulation’s range of in-situ external cavity wall products have been subsequently tested, have thermal performance declared to Lambda 90/90 and are fully compliant with the new BBA requirement.
The move towards Lambda 90/90 will ensure that specifiers are able to compare like-for-like values and have complete confidence that the selected product or system has been tested to the same standards.
For products which are not re-tested to declare thermal performance to Lambda 90/90 within the required timescale, there is a chance that either thermal performance penalties will be applied, or BBA Certification may be withdrawn altogether.
Thermal performance of in-situ formed insulation products has previously been calculated using a Lambda mean (or λmean) convention. In order to declare thermal performance to Lambda mean requires testing a range of production samples and calculating the mean, or average, thermal conductivity of that range.
The Lambda 90/90 method refers to the value that can be obtained for 90% of production within a 90% confidence level, and thus increasing confidence in the declared thermal performance value. This method has been in use for over 10 years for factory formed insulation products.
It is expected that products which have not been adapted or re-engineered to meet the changes will face an increase (worsening) in the declared thermal conductivity value when moving from a Lambda mean declaration to a Lambda 90/90 declaration.
Knauf Insulation’s complete range of in-situ formed insulation products have been re-tested and now have thermal performance declared to Lambda 90/90 as per the BBA requirement. The products have been developed further to ensure that there is no worsening of thermal performance when switching from Lambda mean to Lambda 90/90.
“We fully support the new requirement as it brings clarity to an extremely clouded situation,” comments Steve Smith, market manager – residential new build for Knauf Insulation. “By employing a standard thermal conductivity test methodology specifiers can have complete confidence that the products have been subjected to comparable test regimes and the product or system will deliver the level of thermal performance specified.”