Building Regulations 2000 Approved Documents L1A, L1B, L2A, L2B – proposed revisions

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To:

The Chief Executive Unitary, Metropolitan, District and London Borough Councils in England County and County Borough Councils in Wales The Town Clerk, City of London The Clerk, Council of the Isles of Scilly The Sub-Treasurer, Inner Temple The Under Treasurer, Middle Temple

Approved Inspectors

cc:The Chief Executive: County Councils in

England The Chief Fire Officer: Fire Authorities in

England and Wales Our Ref: CI/46/02/05

18June 2009

Dear Sir or Madam

Building Regulations 2000 Approved Documents L1A, L1B, L2A, L2B – proposed revisions Multi-foil insulation

Communities and Local Government (“the Department”) has today issued a circular to all building control bodies (“BCBs”) and other interested parties about the results of the consultation published on 5th June 2008 about proposed new editions of the Approved Documents L, which contain practical guidance on compliance with the energy efficiency requirements of the Building Regulations in common building situations.

I am writing to let you know that none of the consultation responses contained any new evidence that would cause the Department to change its 2006 approach about the measurement of the thermal performance of multi-foil insulation. In the light of this, Communities and Local Government Circular 07/2007 has been withdrawn along with all previous advice on multi-foil insulation products. The Department therefore declares that it has reverted to the position previously promulgated in 2006 in relation to the measurement of the thermal performance of multi-foil insulation products.

Sarah Sturrock Divisional Enquiries: 020 7944 5721 Deputy Director, Sustainable Buildings Fax 020 7944 5719 Department for Communities and Local Government Email : enquiries.br@communities.gsi.gov.uk 5/G10 Eland House Web site : www.communities.gov.uk

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To assist local BCBs in dealing with individual cases where the use of multi-foil insulation products are proposed, the Department’s position on this material is set out below.

It is the function of BCBs to determine whether building work complies with building regulations, and in particular in this case with the energy efficiency requirements (i.e. regulations 4A, 17C and 17D of, and Part L of Schedule 1 to, the Building Regulations 2000). Consequently, BCBs are free to decide for themselves whether or not to accept that construction details put to them comply with the Regulations, and whether claims about the thermal performance of products are correct. This has always been the case.

Multi-foil insulation products consist of several layers of foil separated by other materials, which inhibit heat loss by both providing a non-conductive barrier and by incorporating elements which reflect heat back towards its source. As you may be aware, there is a scientific dispute over the appropriate test method for measuring the thermal performance of multi-foil insulation products. Some multi-foil insulation manufacturers consider that the most appropriate method is comparative (‘in situ’) testing.

The Department maintains its previous view, based both on international scientific opinion and on new and previous scientific advice commissioned and published by it, that, currently, the only appropriate methods for measuring the thermal performance of materials and products are the “hot-box” test, which is a British Standard test based on Standardised European Norms, or tests that have been agreed at a European level, such as those which form part of an agreed ETA for a product or products. Consequently, at present, only results from hot-box or approved ETA tests carry a statutory presumption that they are correct. Therefore the references in the four Approved Documents L to measuring U-values using the methods and calculations set out in BR 443 (2006) ‘Conventions for U-value calculations’ apply.

The Department accepts that the scientific dispute over test methods for measuring the thermal performance of multi-foil insulation is likely to take some time to be resolved. However, as has always been the case, manufacturers of multi-foil insulation products can seek to persuade BCBs that they should accept claims for their products’ performance based on comparative (‘in situ’) testing, and BCBs are free to make their own judgements about compliance with the regulations based on their assessment of these claims.

Yours faithfully

Sarah Sturrock

Deputy Director, Sustainable Buildings