The key issue of concern relates to the way the insulating properties of multi-foil products have been tested. For many years, the appropriate method for determining insulation performance has involved the use of “Hot Box” testing in accordance with National and European standards. There is no reason why multi-foil insulation systems cannot be tested using this method, indeed one manufacturer has already done so and markets its product on the basis of these test results.

There are several key changes which result from the revision of part L which have a significant impact on the acceptance of multi-foil insulation products-

• Paragraph 11 of AD L1B now clearly states that “U” values must be calculated using the methods and conventions set out in the 2006 version of BR 443. This is significant because the 2006 version of BR443 makes specific reference to multi-foil insulation products whereas the previous version did not.
• Paragraph 3.10.2 of BR 443 (2006 version) now clearly states that “U” value calculations for multi-foil insulation products must be calculated using performance data “measured by a Notified Body accredited for thermal testing by an EU national accreditation service” and tests themselves must be carried out to appropriate BS EN standard.

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