daestrom wrote:
wrote in message
...
News wrote:
The British Advertising Standards Authority... [objected to] a brochure
for roof insulation. The brochure stated "TRI-ISO SUPER 9 Insulation for
roofs was... Thermally equivalent to 200 mm of mineral wool when
installed
in a roof situation, as certified by the European certifying body, BM
TRADA
CERTIFICATION (following real building trials...
... Actis said they had commissioned BM TRADA Certification Ltd (BM
TRADA)
to test, assess and report on the TRI-ISO Super 9 product. They
provided us
with a copy of the BM TRADA Certification and Report dated August
1997 and
said that it substantiated their claims... They pointed out that BM
TRADA
had used "in situ" testing involving a real external environment with
variations in temperature, humidity, etc. rather than the traditional
methods of laboratory testing...
... We understood that BM TRADA had tested TRI-ISO SUPER 9 and the
mineral
wool in two separate roof installations. However, we noted that BM TRADA
had not used the standard industry methods of testing and that the
report
provided by Actis did not include sufficient detail to support their own
methods of testing.
We acknowledged that BM TRADA Certification was a leading multi-sector
certification body accredited by the United Kingdom Accreditation
Service.
We considered that the BM TRADA report did not provide enough detail to
support their methodology...
... ie they faulted the test documentation, vs the result.
We understood that RT was a symbol of total thermal resistance and
typically
had the standard unit of measurement of mēK/W. We noted that the claim
"RT=5" was not qualified by any recognised units of measurement e.g.
mēK/W
and a small footnote stated only "in situ measured values" without
further
explanation. Because the value of 5 was not qualified by any recognised
units of measurement, we considered the claim "RT=5" was ambiguous and
should be qualified in future.
... and they faulted the lack of explicit units in the advertised result.
However, we noted that the BM TRADA report did specify an overall
resistance
(RT) of 5.0mēK/W derived from the in situ testing...
Picky, picky. Reflectix does advertise some system R-values:
http://www.reflectixinc.com/script/p...duct.asp?ID=64
http://www.reflectixinc.com/script/p...duct.asp?ID=77
http://www.majorgeothermal.com/PDFs/.../Solutions.pdf
The US R16.8 crawl space number is interesting.
An important question here is how does other insulation perform
'in-situ' if measured the same way as this product.
If this product can achieve an RT=5 'in situ', that means the overall
measured insulative performance is 5 m^2-K/W. That performance includes
the affects of convection and radiant heat transfer from the living
space to the product, and from the product to the environs on the other
side.
But what is deceptive about this, is that if I were to put a simple
piece of conventional building insulation that has an RT=5 value in the
same circumstance, it would undoubtedly have an 'in situ' performance
that is *better* than 5.
Conventional insulation would only be between the floor joists. For 2
bys at 16" centers that means that 12.5% of the area is the insulation
value of only the joist. I would think that would be around a US R6 for
a 2 * 6. There will be a point of diminishing returns for conventional
insulation, just because of that. Don't forget that under most floors
you have a maze of plumbing and wiring and that has to be worked around
with conventional insulation.
The more interesting question in my mind, is whether this would be a
good afterfit for an existing structure. It certainly would be easier
(crawl spaces are no fun!) to install and it would be a complete seal.
It seems to me that most energy lost is in existing structures rather
than new construction. The option of tearing down the old house and
building a new does not exist for most people.
I would be delighted to have a US R 16.8 floor in my '20s house. At
this point underfloor radiant with radiant bubble looks attractive, not
sure which way I will go and I'm open to other suggestions (like foil
backed iso).
Jeff
Because added to the material's own RT=5,
would also be the affects of the convective layers on each side (just
like this product), and the radiant transfer to/from the surfaces.
Unless this products RT value is calculated by taking the 'in-situ'
performance and *subtracting* the insulative performance of those items
common to *all* installations, the RT value is inflated by those other
factors. Thus when compared with other materials tested in the more
traditional manner, it overstates this product's performance.
daestrom