More Musings of an Energy Nerd
Manufacturers of foil-faced bubble wrap are still convincing a significant number of homeowners to buy their worthless products out of the mistaken belief that bubble wrap is insulation. It isn’t.
Even worse, a few contractors—some of whom are ignorant, and others of whom are dishonest—substitute bubble wrap for insulation in a few critical locations where real insulation is needed: under concrete slabs, for example, or on the outside of metal ducts.
Back in 2014, I wrote a GBA article warning readers to “Stay Away from Foil-Faced Bubble Wrap.” My advice still applies to the current crop of worthless bubble-wrap products. Unfortunately, the decades-old bubble-wrap scam has not gone away.
Blurring the line between material R-values and assembly R-values
We’ll start by outlining the basic facts about foil-faced bubble wrap:
Bubble-wrap marketing materials often tout ridiculously high R-values that have nothing to do with the thermal performance of the material; the exaggerated numbers are based on assembly R-values, not material R-values. Assembly R-values take credit for the R-value of building component layers that aren’t sold by bubble wrap manufacturers: things like layers of plywood, drywall, or air spaces located between the bubble wrap and an adjacent surface.
If a manufacturer is claiming that its product is a type of insulation—and some bubble wrap manufacturers are doing exactly that—then the advertised R-value for the product must be the R-value of the product alone, not an assembly R-value that includes the R-value of plywood, drywall, or air spaces. This isn’t just my opinion; it’s a principle established in a federal law (16 CFR 460) called the R-value Rule. The R-value Rule applies to manufacturers, retailers, and builders. Exaggerating product R-values…
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28 Comments
Hard to believe they get away with this stuff. Something similar we are seeing in Florida is the use of FiFoil as the only insulation. Solid masonry (CMU) buildings have interior framed walls that are then covered with FiFoil sheets leaving an air space that is apparently acceptable to the code officials as adequate insulation.
Carl,
This product -- "VR Plus" -- is distributed by FiFoil, as you say. The R-value label on the facing of the product looks deceptive to me; I'm not sure how the company avoids federal prosecution for violations of the R-Value Rule.
According to a FiFoil web page, "This unique insulation has multiple layers that separate when installed to create three reflective air spaces, with R-values up to R-7.1 on 1.5” furring." This sentence clearly indicates that FiFoil is talking about an assembly R-value, not a material R-value -- raising questions about the legality of the R-value numbers on the product label.
I found an information sheet on VR Plus that is misleading. (See screen shot below.) Especially misleading is the sentence, "The label shows the R-value of the insulation." It does not, for two reasons: (1) This isn't insulation, and (2) the R-value on the label is an assembly R-value, not a material R-value.
The FiFoil website is pretty interesting. The VR Plus product might be useful in some applications, the way it ideally can expand to create two internal 1/2" gaps, with low-e surfaces facing them, plus add a cavity gap that might be anywhere from 1/2" to 2.5", also facing a low-e surface. Depending on the temperature you are operating at, a low-e 1/2" gap can have a thermal resistance corresponding to about R-2.5 according to the tables in ASHRAE fundamentals. So R-5.1 is reasonable for the actual unit that is sold, but listing R-7.1 is clearly in violation of that rule--one can't sell 1/2" polyiso as R-6 counting on an air gap.
But their installation instructions are note adequate to get that result in practice: To prevent air circulation around those baffles, you'd need to close off the channels at the top and bottom, and also make sure the cavity behind it was closed off at the top and bottom, as well as sealed all the way around.
They also have a product called "GFP" which was developed at Lawrence Berkeley Labs that is similar, but in the form of multilayer seal pouches you can inflate with air, or argon for better performance. Or krypton or xenon even.
https://www.fifoil.com/product/p/gfp-insulation
Even thought it's a greatly superior product, the R-value is sold as 5.0 inflated with air, and 6.4 inflated with argon, lower values than the VR-Plus. With GFP, the product itself is inflated, whereas the VR-Plus instead has inflated R-values.
Back in the first half of the 20th century, multilayer low-e insulation was used in insulation for cold storage rooms, and was pretty great compared to the alternatives, before styrofoam was invented. It could still be viable in some situations, and it's a shame that the manufacturers seem to focus on selling it based on false claims rather than on products like GFP that could, unlike most of these, actually make it work better than 1935 cold-room insulation. There's a beautifully illustrated brochure at https://archive.org/details/FactsAboutInsulation showing an assembly with five layers of "silvercote" insulation with furring between each layer, and quoting a U-factor, "confirmed by Professor J.C. Peebles", 0f 0.07. That's about R-2.4 per gap, which is pretty reasonable. But also a lot of work to get R-14.
Charlie,
You're right, of course, that multiple layers of aluminum foil or Mylar, alternating with air spaces maintained by battens or other spacers, can achieve useful R-values. There are at least four problems with this approach: (1) It's usually requires a more labor-intensive installation technique than installing insulation; (2) the effectiveness of the foil surfaces can be gradually degraded by the accumulation of dust; (3) the foil layers may sag or deform, lowering thermal performance; and (4) the method usually costs more than just installing insulation.
While it's true that an assembly consisting of multiple air spaces and multiple reflective layers can have a decent R-value, that doesn't mean that manufacturers of reflective products should exaggerate their products' R-value. All I want them to do is tell the truth and follow federal law.
Finally, I think that the 1935 publication, "Facts about insulation," is a great find. It's a lot of fun to read.
Thanks for sharing this information. Assembly R values is not something I had heard of before and I will watch for it now!
I’ve had this stuff suggested to me before as a replacement for foam, and wrapped on both sides no less, so you would have wooden studs surrounded by double vapor barriers. To be fair to the places selling these things, I suspect it’s the product’s disingenuous advertising and lack of understanding from the people listing these things rather than an attempt by lowes, etc. to scam people. That doesn’t mean they shouldn’t be held accountable though.
Carson,
Lowe's specializes in building materials. There really isn't any excuse -- if they don't understand what they're selling, why are they in the building materials business?
It seems to be the state of the industry. Amazon, etc have millions of listings and competency is expensive. The standard way of sorting through false listings are user reviews, but even those can be sketchy.
Carson,
If Amazon, which is one of the largest retailers in the country -- an immensely wealthy company, awash in cash -- uses sales pitches that violate federal law (and uses fraud to entice buyers), then that retailer isn't trying very hard.
Martin, Amazon is rife with fake reviews, fake products and scammers selling stolen merchandise. They turn a blind eye, just like ebay, Craigslist etc.
Is there some department we could complain to? The FDA seems to crack down immediately on any deceptive claims on supplement products yet we have this stuff claiming it is good insulation. A lot of energy is being wasted because of severely under insulated buildings using these type of products.
David,
Complaints should be addressed to:
Division of Enforcement
Bureau of Consumer Protection
Federal Trade Commission
600 Pennsylvania Avenue, N.W.
Washington, DC 20580
My go-to contact there was always Hampton Newsome. I'm not sure whether Hampton Newsome still works there, though. Here is Hampton's contact info:
Hampton Newsome
202-326–2889
[email protected]
Here is another contact:
Robert Frisby
Assistant Director
Division of Enforcement
Bureau of Consumer Protection
Federal Trade Commission
600 Pennsylvania Avenue, N.W.
Washington, DC 20580
202-326-2098
[email protected]
I've corresponded with the Division of Enforcement for years, going back to 2000 or 2001. My impression is that the lawyers at the FTC are well-meaning but underfunded, and that they lack the resources to pursue violations of the R-value Rule.
Many (all?) state Attorneys General have a consumer fraud division. In some states, they are very receptive to this sort of complaint.
Fred,
If you, or any other GBA reader, is able to get a state Attorney General's office to look into any of the listed frauds, I'd be eager to hear your report.
“[Deleted]”
Kevin,
You should ask your weatherization program whether their insulation crews are familiar with blower-door-directed air sealing. For an old house like yours -- one that "leaks cold air from the baseboard" -- it's a good idea to perform air sealing work before the cellulose insulation is installed. (For more information, see "Blower-Door-Directed Air Sealing.")
Assuming that your weatherization crew is experienced and knowledgeable, cellulose insulation is a good fit for an old house like yours.
I don't think that the aluminum foil layer shown in your photo will cause problems, for two reasons: (1) In Climate Zone 4A, your house won't experience cold winters, and (2) the asbestos-cement shingles are corrugated, and these corrugations will help eliminate any small accumulation of moisture.
What about the product as simply a radiant barrier and the benefits of what it can do in direct sunlight? I lived in Florida with an all black car and black interior. Having this reflective shiny stuff (maybe foil or mylar) in the front windshield makes a world of difference when the sun is beating down. I feel like the plastic bubble wrap helps give it shape and rigidity for such an application. It might be worth stating that radiant barrier products needs an air gap to be effective . I agree that the advertised R value is bogus, but perhaps there should be another type of rating for this sort of material and its "value" - which likely wouldn't be much in a cold and overcast environment. Turns out my least favorite condition is direct sunlight, even in Oregon where I live now. Also similar products advertise foil faced closed cell foam which seems to be more popular with professional builders.
Green Bee,
Radiant barriers can be useful (and not only in direct sunlight; they also work in the shade). But if you want a radiant barrier, you can buy cheaper products (thin aluminum foil or Mylar sold for building purposes).
For duct insulation, slab insulation, or wall insulation, you don't want a radiant barrier -- you want real insulation.
For more information on radiant barriers, see "Radiant Barriers: A Solution in Search of a Problem."
It is used around here under metal roofing for barns and overhangs that use purlins instead of plywood subroof.
What is this thin R4 foam board that is cheaper than the bubble wrap? I ask because I was planning to use the bubble wrap to keep water from dripping under roof of shop building since I thought it was the cheapest option.
I am in zone 4a
Thank you. -Mike
Mike,
The prices for building materials are in flux right now because of nationwide shortages, so the math has changed slightly since I last made the calculations. It would be more accurate to say that foil-faced bubble wrap costs just as much per square foot as R-4 rigid foam.
The price comparison was originally made when I was providing advice for people looking for sub-slab insulation.
Right now, 1-inch-thick EPS rigid insulation (with an R-value of about R-4) costs 53 cents per square foot at Lowe's. Reflectix bubble wrap costs 53 cents per square foot at Home Depot.
In your case, I'm not sure which product makes the most sense. If all you want to do is collect condensation water and direct it to the eaves, you might be able to use roofing underlayment. If you want to add R-value to your roof, the bubble wrap won't add much -- but the EPS foam wouldn't be easy to install unless you add roof sheathing, which is costly. A radiant barrier (without the bubble wrap) might work just as well as the foil-faced bubble wrap.
Dear Martin: Thanks for this important update on the Shiny Bubble Wrap scam: Another key point to note: Reflective / radiant barrier products perform particularly poorly in winter because cold cannot be 'reflected' and the warmer air inside your home is not 'radiant' (not emitting a bunch of infrared energy). This is underscored by the 'tests' that Reflectix performed to 'validate' their claimed results. If you look at the details, all but one was run in warm temperatures , e.g. 70 degrees. Only one test was done in the winter for a cathedtral ceiling. Reflectix claimed R-7 in the northern USA for a cathedral ceiling -- with the air gap -- but only R-1 in the winter. A copy of the Reflectix FTC statement is attached, which lists the claimed R-values.
Independent testing in Texas showed that there is only one legitimate application for a reflective / radiant barrier product: in a standard ventilated attic on hot summer days. You can simply lay a reflective / radiant barrer down on the attic floor, over whatever insulation is there, and it will reflect ~28% of the heat flux from the hot roof and reduce HVAC costs by 2% to 4%. Dust accumulates on the reflective surface, however, which can significantly impact performance, so you have to shake the dust off every spring. A copy of this study report is attached below.. It is also important to note that this reflective / radiant barrier is NOT a substitute for good attic insulation.
I am one of the top 10 people in the USA who answers customer questions on the Home Depot website. I often receive questions about reflective / radiant barrier products -- and explain the reality vs the claims on the package. To Home Depot's credit, they publish my answers. I wish they would eliminate these products from retail store shelves as well.
I've gotta take the devil's advocate here... This argument goes against my experience of sleeping on an air filled mattress while backpacking. The mattress is a thin rubber coated canvas with about 1 1/2" to 2" compartmentalized air spaces when inflated. It definitely keeps me from experiencing the cold ground or snow below me. Can any of you guru's explain the difference/science to me? All these backpackers can't be getting fooled, can they?
Kent - I love my NeoAir sleeping pad, and it's very cleverly designed.
This is my lay person interpretation - I'd be very interest to hear alternatives: First, the NeoAir (the one I have) has reflective (radiant) barriers between the triangular cells. Body heat, while less than 98 deg, is still warm enough to be reflected back to the sleeper. The triangular shape of the cells means the "cold" cells - those with the wide part of the cell against the ground - are almost thermally broken from the top (i.e. at the apex of the triangle). The "warm" cells have a broad surface against your body, with the 'almost thermal break' (pointy part of the triangle) at the ground, and with the radiant surfaces reflecting body heat back up. Air is a poor thermal conductor (i.e., good thermal insulator), and heat loss will need to be mostly via conduction through the walls of the air cells, then via the air which is slow (i.e., good insulation), assisted by the radiant properties. There's restricted air movement between cells, as evidenced when inflating/deflating. So as noted above, the pads are using "relatively sealed" cells. There may also be fancy manufacturing that allows air flow among only top or only bottom cells, which would further enhance performance and comfort.
I'm talking specifically about the newer, high-tech pads. The old-style air mattress, which are just air-filled tubes, don't compare - the old style are really cold when e.g. sleeping on snow.
Dear Chris: I agree -- although as the size of the air gap grows, so does circulation and heat transfer between hotter / cooler surfaces, which reduces the "insulation". That's why most thermos bottles use a vacuum between the outer shell and inner container - vs standard air.
As you noted, this is also why insulation materials, e.g. foam board and rock wool, are much more efficient insulators than a simple air gap. Plus an unsealed air gap, e.g. between a hot attic deck and a reflective / radiant barrier, basically becomes a solar heating system -- which releases super-heated air into your attic. Plus, as noted above, reflective / radiant barriers gather dust over time which sharply reduces their effectiveness. Plus reflective / radiant barriers do not work well in the winter because cold cannot be 'reflected' and the moderately warmer air inside your home (or the warmth of your body) are not 'radiant' -- emitting significant amounts of infrared energy.
So I spec this insulation on ducts (entirely inside in the thermal enclosure *only*) for short runs on ducted minisplits to prevent condensation. I don't think I need much R-value there. It's the only place I can see using it. It's thin, clean to work with, and I don't need much R-value (it's just wrapped tight, none of this air gap silliness). What are people's thoughts on that use?
Hey Cramer--yeah, I agree--that's a use that I consider acceptable, on the scale of things. Even if it provides R-1, that should be enough to avoid condensation issues.
There's that old joke from the Soviet Union: the workers would say “We pretend to work and they pretend to pay us.” It feels like that's somewhat analogous to what's going on here.... we pretend that bubble wrap insulates...
Dear Cramer: Even if your ducts are short runs inside the 'the thermal enclosure', it would be smart to insulate the ducts - to avoid wasting money heating / cooling enclosed and hidden spaces. Reflective / radiant barrier products provide almost no insulation value by themselves, typically just R-1.
I faced a similar question at our previous home. All of the HVAC ducts were installed in 'conditioned space', but (obviously) it would be a good idea to deliver every BTU (or -BTU) to the rooms rather than the hidden spaces in the walls or attic. I used R-8 insulated flex duct for all of the straight runs, linked to metal duct elbows, air-selaed all of the joints, and wrapped everything (plus the plenum) with MasterFlow R-8 duct wrap, and sealed all of the seams with foil HVAC tape (not silver fabric 'duck' tape). See the photos below.
The duct wrap added a noticeable boost in effeciency . I should have measured the temperatures at the registers before / after the duct wrap was installed, but unfortunately I was in a hurry. My wife and I both could feel the difference, however - which makes sense.
This step also helped us earn a 'Pearl Platinum' rating for our home when we put it on the market, which was worth an extra ~$60K.
So doing a better job with HVAC duct insulation pays off now -- and later. If you take this additional step, take photos that you can use later to prove that you did a good job insulating the HVAC ducts -- not the typical 'wrap it with shiny bubble wrap'.
I hope this is helpful.
Mark
I found two uses for this stuff, exterior solar window shield for my cars and making cozies for my ice chests. I found I can extend the life of my ice supply by two days, especially if they aren't being opened all the time. I bought some to teach my energy classes what not to use and didn't want to waste the stuff. so I made ice-chest cozies for me and my entire camping group.
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