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Multi Layer Foil Insulation Products
Don’t believe the sales hype: this ‘space age’ technology is not all it’s cracked up to be…..
Super 10 is the latest in a line of multi-layer foil products produced by Actis. Although it is only about 30mm thick, Actis claim that tests have shown that it has the same insulation value as much greater depths of mineral wool. This has lead to great interest from within the building sector. Super 10 is more user-friendly than mineral wool and its lesser bulk means it can be deployed much more easily in confined spaces.
Although mineral wool (more commonly known in Ireland by its brand name Rockwool) has something of a reputation for being the poor man’s insulation, there are few products on the market which have been proven to achieve an equivalent thermal resistance (the ‘R’ value) with a significantly less depth of material. Any new product capable of achieving the same thermal resistance with only one sixth the depth of material would revolutionise the building industry.
Actis’s claims, however, appear to defy the laws of physics. Although Tri-Iso Super 10 is credited with being able to efficiently reflect back radiant heat losses, most heat losses from buildings occur as a result of convection or conduction.
Independent Tests and Research
A number of individuals working in the sustainable building sector were not convinced that the full story was being told by Actis and decided to carry out their own small scale tests. Although far from conclusive, the results suggested that the multi-layer foil insulation might not be the miracle product the manufacturers claim .
Then in July 2005, the Building Research Establishment (BRE) in the UK investigated two buildings in Scotland which had been fitted with Tri Iso Super 9, the predecessor to Super 10. The results of the study² indicated that the thermal resistance of the Super 9 was about 1.71 m²K/W. Actis had claimed a figure almost three times asgreat. The research carried out by BRE was funded by the ODPM (Office of the Deputy Prime Minister).
The BRE findings have some serious implications. Anyone assuming that a building insulated with Tri-Iso Super 10 (or other similar product) will be compliant with building regulations is likely to be disappointed. The architects who specify such products and the building engineers who sign off houses insulated with them may be leaving themselves open to litigation from clients who will understandably be very angry that their new home is not insulated to the required standard.
Far from asking questions, many builders are recommending Super 10 or its contemporaries to clients and are delighted to have found a product that is so quick and convenient to install………
For the rest of this article, and the results of independent tests carried out on a number of insulation products by the Sustainability Institute, please refer to Issue Sustainability journal #1
Local Authority Building Control Technical Guidance Notes
In August 2006, the UK LABC Technical Guidance Notes made a number of recommendations with regard to the use of multi-layer foil insulation products. These notes drew attention to tests carried out by the UK National Physical Laboratory which indicated that the multi-foils tested had an 'R' value of 1.69-1.71 m2K/W not the 5.0-6.0 m2K/W claimed by the manufacturers. The document went on to recommend that these lower values be adopted in the calculation of 'U' values, the unit of measurement used to determine thermal transmittance.
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