Helpful? -1

Why is "reflective insulation" still being sold by HD and Lowes -- and used by many contractors?

I stopped by my local HD for more supplies and was surprised to see rolls of "radiant barrier" bubble wrap on the shelf. Lowes and online vendors sell products with similar claims. For example, here are the benefits promised by a leading vendor:

"An easy-to-install double reflective, double bubble insulation

R-values range from R-3.7 to R-21 depending on the applications

Energy-saving residential applications include: cathedral ceiling, crawl space, radiant floor,
wall, HVAC duct, water pipe, garage door, knee wall..."

R 21 ?? !! As GBA articles and posts note, the typical claims for radiant insulation are snake oil, put to the lie by 20 years of independent studies, FTC and Attorney General actions etc.

Unfortunately, builders, contractors and customers continue to fall for these claims. For example, the HVAC contractor at our latest project showed up with a big roll of Reflectix and began to wrap the plenums. The label on the Reflectix roll boldly claimed "R6", with a small note that R4.2 was the expected level of insulation with HVAC ducts. if you read the excellent reviews and commentary on GBA, you know you should read this fine print very carefully. R4.2 is only achievable with a perfect assembly, a consistent air space and horizontal orientation -- and no dust on the foil surface.

These claims are not unique; launch a Google search for "reflective \ insulation" and see how many products and extravagent claims appear in your browser.

This is a whack-a-mole problem. When one vendor is hit by the FTC or an AG suit, another pops up. "Reflective insulation" is very cheap to manufacture, so new products quickly appear with more wild claims.

It is past time, well past, for professional builder organizations to join together nationwide -- and put an end to this charade.

Included below are links to a number of reputable sites and independent studies:

Healthy Heating: 20 years of research studies on reflective 'insulation':
http://www.healthyheating.com/Page%2055/Page_55_o_bldg_sys.htm#.UqHyQMRDvNk
(Scroll down to see the newer studies)

GBA: Is Bubble Wrap Duct Insulation a Good Idea?
http://www.greenbuildingadvisor.com/blogs/dept/qa-spotlight/bubble-wrap-...

Energy Vanguard: The Foil Faced Bubble Wrap Sham
www.energyvanguard.com/blog-building-science-HERS-BPI/bid/29497/The-Foil...

GBA: A great collection of all of the questions and claims for HVAC installers:
http://www.greenbuildingadvisor.com/community/forum/green-products-and-m...

A copy of a thorough 2010 study by the Canadian National Institute for Research in Construction is also attached. Their conclusion: In a perfect state (with no dust on the surface), a radiant barrier with an air gap increased the efficiency of insulation in a wall by 10%. In other words, if the wall was already R6, adding 'miraculous' foil bubble wrap added .6, for a total of R6.6.

Mark

Canada - IRC study of reflective insulation - 2010.pdf450.84 KB
Asked by Mark Hays
Posted Fri, 12/06/2013 - 22:59

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8 Answers

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1.
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Mark,
You're preaching to the choir; of course I agree with you. GBA has been whacking this mole every time it pops its head up.

For more information on reflective building products, see Radiant Barriers: A Solution in Search of a Problem.

For more information on bubble wrap, see Martin’s Useless Products List.

Like you, I am frustrated that the FTC, a government agency charged with protecting consumers from fraudulent claims by manufacturers, is asleep at the switch. There are several factors behind the FTC's unwillingness to act. The agency is evidently underfunded. Another problem is that our country's educational system does not produce high school graduates or college graduates with a grounding in science. As a result, thermal transfer issues are confusing to lawyers, and the lawyers at the FTC are easily bamboozled by manufacturers' mumbo-jumbo. The bamboozled FTC lawyers end up not pursuing these cases.

Answered by Martin Holladay, GBA Advisor
Posted Sat, 12/07/2013 - 06:41
Edited Sat, 12/07/2013 - 06:43.

2.
Helpful? 0

Dear Martin:

Thanks for your quick reply. I sent all of the info in my Q&A post to Home Depot and Lowes, and I plan to follow up with a phone call. Maybe some pressure on the commercial end will achieve some results, while the FTC sleeps.

Answered by Mark Hays
Posted Sat, 12/07/2013 - 12:21

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Helpful? 0

The best use of the aluminized bubble-wrap I've seen to date is the tightly taped outer wrap of a pallet of cases of wine being shipped on container ships, the binder holding the 2-3" of type-I EPS together, protecting the high-value cargo from getting bashed, and keep it's temperature reasonable. The high thermal mass of the contents and the moderate R of the EPS layer, combined with the air-tightness and low-E aspect of the bubble wrap keep the temperature extremes seen by the wine well bounded, independent of the weather in-transit.

Inside of building assemblies the number of layers and construction details required to tease the performance out of it in a code-compliant manner is more trouble than it's worth. With perfectly air-tight assemblies and enough layers with gaps (but no convection) between them, it's possible to hit any arbitrary thermal performance point, but if it were easier or cheaper to get there with a radiant barrier approach the world would have gone there ages ago.

Answered by Dana Dorsett
Posted Mon, 12/09/2013 - 17:09

4.
Helpful? 0

Dear Dana: Exactly. "Radiant barrier" insulation has almost no R value by itself; the results depend on the air gap, the angle of the assembly, the existing insulation, the location of the building etc. Here are a couple of quotes from Reflectix literature: (1) "A reflective product installed in an open attic as a Radiant Barrier has no R-value. R-values for reflective products are obtained when the product faces an air space in a “enclosed cavity”." (2) Another document notes that performance is limited to "R2" in the winter in southern states, and "R1" in the north.

These are only two examples of the key problem: the difference between marketing hype and facts with reflective products -- even the company's own facts. If you read the label on a roll of Reflectix or the Reflectix product description on the Home Depot or Lowes websites, for example, their solution looks simple, effective and easy to install, e.g. "R-values range from R-3.7 to R-21 depending on application." Customers need to search the Reflectix website and read a number of documents carefully to discover the actual requirements and limitations.

I also found that published "performance studies" have to be examined carefully, e.g. the claim of R 21 performance in a crawl space. (More than three inches of polyiso foam board!) I dug into the details and found some surprises. I will add the details and copies of the documents in my next post.

Mark

Answered by Mark Hays
Posted Mon, 12/09/2013 - 19:44

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Helpful? 0

Update: The "study" that backs R21 claims from Reflectix

I was surprised that Reflectix would claim "R-21" performance in crawl space applications. Even three inches of polyiso foam will not reach R-21. So, I checked the Reflectix website:

> Guess how they justify R-21? A "study" done in January, 1991 by Holometrix Inc. Yep, 1991 -- more than 20 years ago. (A copy is attached.)

> Was the study independent? No. Reflectix ordered and paid for it.

> The performance of Reflectix depends on the complete assembly. So... does the assembly tested by Holometrix in 1991 match the R-21 assembly recommended by Reflectix in 2013? No.

> Guess how many people worked for Holometrix? Just two, according to a research report I purchased from Hoovers. (A copy is attached.) Reflectix clearly picked a leading testing firm!

This is not the end of the story. The Holometrix 'study' includes lots of formulas, and claims to be based on ASTM standards. I purchased a copy of the matching ASTM standard. (A copy is attached.) If you are familiar with math and the analysis of construction materials, compare the ASTM standard and definition of R value to the formulas and results in the Holometrix study. Note the differences.

In short, this is another example of the gap between facts and marketing hype.

Mark

AttachmentSize
Reflectix - Holometrix study from 1991.pdf 1.77 MB
Holometrix report from Hoovers.pdf 457.61 KB
ASTM Standard for Reflective Insul in Building Apps - 12.7.2013.pdf 95.57 KB
Answered by Mark Hays
Posted Mon, 12/09/2013 - 20:07

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Don't throw the baby out with the bath water. Although I agree that "R value" is a term inappropriately used for radiant barrier product, your article leaves people beliving radiant barrier is of no value at all. My own empirical evaluation suggests just the opposite. Where energy consumption is related to unwanted solar gain, radiant barrier products can make a huge difference! Using a radiant barrier product reduced my garage temperature enormously. Period!!I used a double sided bubble wrap product versus film because it was easier to handle - not because of any illusion or any manufacturer claim that the minimal R value of the bubble wrap portion would have any substantial efect. No one is suggesting any more that radiant barrier should be applied horizontally, where it will collect dust. But film applied to an inside surface of the roof where the operative surface is adjacent to an air space and is subtantially vertical, is cheap, easy to install and highly effective in hot climates. Who cares what it does in Canad?

Answered by Jane Babin
Posted Tue, 12/10/2013 - 15:10

7.
Helpful? 0

Jane,
Yes, a radiant barrier can make a difference in an uninsulated roof or wall assembly. For this type of building, a radiant barrier works.

But insulation works even better.

Answered by Martin Holladay, GBA Advisor
Posted Tue, 12/10/2013 - 15:30

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Helpful? 0

Dear Jane: Martin hit the 'radiant barrier' nail on the head. Radiant barriers can have an impact on heat gain, e.g. from a hot roof -- but the issue is efficiency vs cost. If your garage roof was insulted with standard foam board, spray foam, rock wool bats or even fiberglass bats or panels, the insulation would be more effective for less cost, year round.

Radiant protection varies significantly from summer to winter. As Reflectix notes in their FTC "facts" document, one layer of reflective insulation -- with an air gap -- will provide R6 to R7 protection in summer, when the roof is hot from the sun. In the winter, however, the efficiency drops to R1 to R2 -- virtually no protection compared to the price. Even if the customer lives in Dallas, the value of that shiny bubble wrap vanishes in winter. So... every customer, from Dallas to Fairbanks, would get better results with standard insulation, at lower cost.

You noted that "no one is suggesting" that radiant barriers should be applied horizontally. Unfortunately, every major manufacturer is pushing exactly that, e.g. Reflectix, RadiantGuard, AtticFoil and eShield, hyping installations in crawl spaces, basements, radiant heat systems, etc.

As anyone who does remodeling / insulation work in attics also knows, dust accumulates on everything -- horizontal or not. The protection provided by a reflective barrier under a roof will degrade over time, as dust accumulates on the shiny surface.

This highlights a key problem with reflective products: performance claims are based on an "assembly", including an air gap and the perfectly shiny surface when the product is installed. Standard insulation products do not make claims based on the "assembly". An inch of polyiso foam board = R6, period. This means that the efficiency of reflective products varies significantly based on the installation, angle of the air gap, the season and amount of sun, the amount of dust that has collected on the surface, etc.

In short, Martin is right. Real insulation works better.

Mark

Answered by Mark Hays
Posted Tue, 12/10/2013 - 19:45

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