|
|
re: the great r-value hoax
1 nov 1997
vince clause wrote:
> a terrible hoax has been perpetrated against the consuming
>public by large mega corporations in control of a multi-billion dollar a
>year industry.
true. foamboard is r-value tested in the same way that fiberglass is,
ie with no wind or moisture, because fiberglass was developed first.
this makes fiberglass look pretty good compared to foam, but in real life,
wind penetrates fiberglass, and as little as 2% (?) moisture in fiberglass
insulation reduces the r-value by 50%.
>any insulation that does not incorporate at least one radiant barrier
>cannot protect well from radiant heat transfer.
false. foam and fiberglass are both opaque to radiant heat transfer.
>glass fiber insulations and cellulose insulation and many other
>insulations insulate by absorbing heat. later they must give off
>that captured heat,
false. they slow the passage of heat, but they store very little heat.
>current r-value ratings are based solely on conductive heat transfer
>through an object.
false. when they measure the heatflow through a chunk of insulation,
convection is measured as well. i suppose radiation isn't, except in
special cases of foil faced insulation. radiant barriers have real
r-values that can significantly slow heat flow, but the r-values change
with temperature, direction of heatflow, and airspace widths, so
non-experts (like me :-) are often confused as to how to predict their
performance, and some manufacturers do not advertise their r-values.
>they(r-value ratings) in no way take into consideration this residual
>captured heat that must be dealt with later in real life situations.
false. the residual heat these insulations is negligible, unlike adobe.
>reprove me in public or private. thanks.
you are reproved.
>vince clause
>director, ecosafe information services
did you say "information services"? :-)
>dare to be different, dare to dream! to dream!
right...
nick
|
|
