[Greenbuilding] under slab radiant barriers

[John E. Beeson]

So do the radiant bubble barriers have a significant air gap to provide
a stoppage to heat flow?  Or is that the 0.1 to 0.5 range you give based
on installation the effective result? 

Thanks,

QUINN EVANS | ARCHITECTS
John E. Beeson, LEED AP
v 734 663 5888

-----Original Message-----
From: John Straube [mailto:jfstraub at civmail.uwaterloo.ca] 

Your question on R-value's is valid, but I meant it as a surrogate label
for heat flow.

R-value is an ASTM test, which abslutely, completely includes radiation.
Heat transfer through fiberglass batt, for instance, is about 40% by
radiation, and through expanded foam is around 30%.
When I said "R-value", I meant "the inverse of heat flow across the
layer divided by the temperature difference".  This includes all modes.
Radiant barriers dont work to stop heat flow without air gaps. Period. I
called this R-value cause thats what most people understand.