Replies

1. GBA Editor
   Martin Holladay | May 19, 2011 12:54pm | #1

   Raff,
   Thanks. This report nicely debunks the exaggerated claims made by sellers of P2000, a brand of EPS with a history of R-Value Rule violations.

   For those who missed it, here's a link to my blog on the P2000 scammers: Beware of R-Value Crooks.

2. 
   user-939142 | May 20, 2011 04:24am | #2

   nice to see some numbers

   one last question though:
   is there any possibility that using a reflective insulation has benefits because it targets a type of heat transfer the others don't? i personally don't understand the whole picture on heat transfer and how the three forms relate...

   so if you have no insulation that targets radiant energy, does that radiant energy get stopped anyway if you use enough other forms of insulation?

   it seems like using a radiant barrier as part of your insulation profile, even if you barely achieve an R value of that of EPS for the radiant barrier portion, you at least handle another form of energy transfer, and the product is not expensive or hard to install in most cases.

3. GBA Editor
   Martin Holladay | May 20, 2011 05:08am | #3

   Bob,
   1. If you know your wall assembly's R-value, you know everything you need to know, because R-value measures resistance to heat flow by all three heat flow mechanisms.

   2. Thermal radiation (radiant energy) travels through air or through a vacuum, but cannot travel through opaque assemblies like plywood, rigid foam, or a few inches of cellulose.

   3. For more information, see:

   Understanding R-Value

   Radiant Barriers: A Solution in Search of a Problem

4. 
   jklingel | May 24, 2011 05:01pm | #4

   "Another great publication by the guys ..." Not to mention the gals, too.