Underslab Bubble Foil Insulation: Reflective Insulation

Radiant Heating Design Guide
radiant floor heat

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Reality Check #1

"An Radiant Barrier System (RBS) with a 3.5" gap has a performance that varies significantly between operating at a temperature of 140 F (i.e., a solar heated roof sheathing) with an R-value of about 10 and a temperature of 0F (a cold winter night) with an R-value of only 2.5. Add additional variables such as dirt accumulation on the barrier and a wide range of performance values can be quoted. In most cases, the annual benefit of an RBS relative to an inch of insulation is small or non-existent:"

source: Building America Special Research Project: High R-Value Enclosures for High Performance Residential Buildings in All Climate Zones Research Report - 1005 29 October 2010 (Rev. 1 February 2011) Author: John Straube Contributors: Joseph Lstiburek, Betsy Pettit, Armin Rudd, Christopher Schumacher, Peter Baker, Kohta Ueno, Alex Lukachko, Jonathan Smegal, Aaron Grin, Ken Neuhauser, Cathy Gates

Reality Check #2

"Based on this test Foil-Backed FB-EPS required about twice the energy to maintain a set-point temperature as did fibreglass batt insulation...

FB-EPS was not able to maintain set-point temperature during a portion of time."

source: Dick, K., Fedirchuk, K., Comparison of Energy Consumption for a Wood Frame Building using Batt insulation and a Foil Backed EPS Foam Board,  University of Manitoba, 13th Canadian Conference on Building Science and Technology, Winnipeg, May 10-13, 2011

Reality Check #3

"...installing them at all in a cold climate is not generally cost effective anyway."

U.S. Department of Energy

Reality Check #4

Has the product been evaluated and registered with the Canadian Construction Materials Centre (CCMC) and if so what does the CCMC report state?

CCMC Insulation Listings


Misleading Claims on the Web 4...Brand-X and Brand Y (July 2011)

They’re back at it again…

Just when you thought it was safe - the faux (foil) insulation crowd is back at it again…here are two recent attempts from the S & M crowd -  aka smoke and mirrors aka sales and marketing masquerading as scientist.

Example #1

Brand X has introduced a “new” 5 mm (0.2") foil backed closed-cell polyethylene foam stating on it's prime web page - an unqualified R-15.67. Yes folks - a whopping fifteen point sixty seven! ...and get a load of this ...it's "new" - imagine that! But hold on it gets better...its "new and shiny"...if I were a fish without a doubt I'd be chasing that new shiny hook - who could resist?

But wait - digging deeper into the website one finds the claim to R-15.67 is specific to direction of downward flow and a requirement for 2.64” of air space on either side of the insulation.  That's right you have to figure out a way to permanently place the insulation in a cavity with 2.64" of dead air space on either side. But wait! At what temperature is the rating and what happens if the air space has convective loops (and the air space will have convective loops)? Does Brand X provide the details? How about a correction factor? How about a clarifying statement? Nay I say not.

At the end of the day the 5mm product itself might have an R-1.0 (that's right a big fat "R - one" not R15.67!) and consumers should know that since the R-value of air is a moving target changing with temperature and convective flows (see sidebar)…the products R-1.0 (one) is the only thing you can count on - something Brand X doesn’t state explicitly – this is just another fine form of obfuscation.

Example #2

From the same company comes the use of the USGBC logo as well as several others under the heading of “Approvals and Certifications”. So here's the thing - the USGBC doesn’t approve nor certify products nor do some of the others listed.

As we have stated before just because a firm or person holds membership in an organization does not mean its product claims are valid – you have to be very careful with these faux (foil) folks.

Example #3

Last but not least if you see a product review category heavily tilted in favor of the product (such as what is shown on Brand X’s website)…ask yourself what qualifications do these product reviewers have? Are they building scientists, engineers, researchers with an accredited testing facility, engineering or science faculty members of a university (see sidebar)?

Some of these faux foil S & M types refer to their customers as "users" so just remember the wise words your Mom gave you about users and dealers...both are hooked and are looking to get you hooked as well.

Example #4

Brand Y has decided to become scientific - this time around stating (incorrectly), “emittance is the amount of radiant heat that passes through the product (that is NOT blocked)”. They go on to assume that a product with an emissivity of 0.23 allows 23% of the incident radiant energy to pass on through with the other 77% blocked. The definition of emittance refers to the materials ability to release absorbed heat via radiant transfer not the amount of “radiant heat” that passes through. This is not semantics - the difference in terms is important stuff.

Furthermore there is no heat in radiant…its electromagnetic energy which gets converted to heat energy when it is absorbed.

A low E or low emissivity material is very poor at “emitting” electromagnetic energy. Often (but not always true) materials with low emissivity have high reflectivity such as mirrors, foils and polished metals.

Energy in the form of heat, absorbed by a material can be conducted or transmitted through the material but this is a function of the materials transmissivity or conductivity and not its emissivity. 

If you've bought into these brands sales pitch contact the Federal Trade Commission toll-free #: 1-877-(382-4357)

If you know others who are considering this product have them read the warnings from consumer protection groups and research reports listed at our main page.

Learn more about insulation and radiant cooling and heating here. Note: Allow up to 60 seconds to load. 


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