Radiant Barriers and their use to satisfy minimum R-value regulatory requirements

It may seem like a basic question, but being based in Australia, I am looking for some guidance on how Reflective Insulation may be used to satisfy thermal R-value regulations for roofs, walls and floors in the US.
More specifically, what are the R-values attributable to reflective insulations in a regulatory context for each of these applications?
Is a reflective insulation (Radiant Barrier Product) deemed to provide a certain R-value for typical building applications? 

Comments

R-Values Can Vary

Mark Lessans's picture

As far as I know, Radiant Barriers are multitudinous, so generally speaking, it is hard to give reflective insulation a certain R-value. Some products do have a small R-value in combination with their reflective value, and these will vary from product to product.

For more information, I'd check out the U.S. DOE Energy Efficiency and Renewable Energy page on Radiant Barriers, which gets into more detail on different installation types. If there is anything more I can do to help you out, just let me know.

Mark Lessans - November 30, 2010 - 4:39pm

Method for determining R-value

Chuck Murray's picture

The method for determining R-value of a variety of products, including radiant barriers is as follows:

From the 2009 IECC:

303.1.4 Insulation product rating. The thermal resistance
(R-value) of insulation shall be determined in accordance
with the U.S. Federal Trade Commission R-value rule (CFR
Title 16, Part 460, May 31, 2005) in units of h ft2 °F/Btu

The CFR is located here:
http://ecfr.gpoaccess.gov/cgi/t/text/text-idx?c=ecfr&tpl=/ecfrbrowse/Tit...

Chuck Murray - December 21, 2011 - 3:23pm

R Value of RB

jasonkaylor's picture

I would personally stay about as far as away from RBs as possible. Determining R value will have to be calculated as Chuck Murray pointed out. The issue with RBs is that unless they have bubble wrap in the middle the R value is going to be basically 0.

RBs work off of E (emittance), not R value. If it has "bubble wrap" in the middle it might have .5 R value, which is still basically zero. Once the RB becomes dirty, in any fashion, its E value will change. In a perfect world an RB should emit at or near .03 (3%). When it becomes dirty (dust, kicked up insulation, etc) it can change to almost the inverse of that.

Eventually the world will wake up and change to U value....which boggles me with all the brilliant minds in this industry why U value is not more readily used.

JJ

jasonkaylor - December 29, 2011 - 3:35pm

Great Lie

PghBob's picture

Radiant barriers are snake oil. I have no idea how foil faced bubble wrap can hit R-4, but I saw it wrapped around a duct with that statement. I see dirty silver vapor barriers getting R-5 and a major builder sends all building officials this lie, with statements about the FTC regs under an engineers seal.

PghBob - September 3, 2012 - 11:26am

X
You may login with either your assigned username or your e-mail address.
The password field is case sensitive.
Loading