On Sat, 30 Sep 2006 23:29:09 +0100, a particular chimpanzee named Tony
Bryer randomly hit the keyboard and produced:

On Sat, 30 Sep 2006 22:38:05 +0100 Hugo Nebula wrote :

I was sceptical too, but it appears to be correct. The R-value of
Alreflex (the nearest equivalent I could think of) with no cavity
either side is 0.15m2K/W; the R-value with cavity both sides is 1.56,
so the R-value with one side exposed must be 0.93. Multiply that
figure by the conductivity of polystyrene (0.037W/mK) and the
equivalent thickness is 34mm so they're not far off.

Note that the following BRE document casts doubt on the TRADA figures
being quoted for this sort of insulation

http://www.planningportal.gov.uk/upl...n_july2005.pdf

That's for multi-foil insulation which tries to claim R-values
equivalent to 200mm of rockwool. Alreflex is bubble-wrap sprayed
silver. The R-value includes a value for the material as well as
increased resistances of the air either side as it has a higher
emissivity (or is it lower?, it's late & I can't remember). The
values I quoted were taken from the BBA certificate for it, so if you
can't believe them, who can you believe?!
--
Hugo Nebula
"If no-one on the internet wants a piece of this,
just how far from the pack have you strayed?"