wrote in message
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Here's one way to estimate the R-value
of a radiant barrier based on the air
gap and the emissivities and surface
temps and the direction of heatflow from

It is?

The British Advertising Standards Authority got Actis, a French company,
claiming their reflective foil insulation is 'Equivalent to 200mm of
traditional Rockwoool insulation'. A complaint has been upheld after ASA
went to independent technical experts.

The judgement can be seen at:
http://tinyurl.com/s6c2p

Think hard before you buy.