European specialty insulation – Actis Hybris
Hello
I am in the process of getting quotes for a prefab small home. One such company is proposing to insulate standard 2×6 stud walls with the below system. Essentially, honeycomb type product between studs, then multifoil stapled over studs and taped, then 1″ battens for a service cavity. The proposed assembly resulting in a 0.18 w/m2k U Value according to suppliers.
Do you having any views on these honeycomb type insulation products? It is not something I’ve come across before. I think the sales pitch is because they come collapsed they are easy to transport, move, cut and fit. It is also much less expensive than polyiso.
http://www.insulation-actis.com/hybrid-system/hybris-uk.html
Secondly, what about the interior multifoil vapour control product. These types of products seem to be quite common here in the UK to boost R Values (or U values as we prefer) without taking up too much depth. Again its not something I can find discussed elsewhere here at GBA.
http://www.insulation-actis.com/hybrid-system/hcontrol-hybrid-uk.html
Thank you
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Replies
The short answer is, your assembly will not reach the claimed insulation values -- not even close. I'm working with US R values, because it's what I'm familiar with, so please forgive me.
For the honeycomb insulation, they claim a little more than R4 inch, which is equivalent to EPS. Digging a little deeper, they used EN16012 to test that performance, so their claim includes air gaps on both sides. Your assembly will not include such details, so it will not reach the claimed performance. I'm guessing it will be less that R2 per inch, but that's just a guess.
That multifoil insulation has a similar story, where they claim an absurd R5/inch. At least they explicitly mention the air gap there. Again, expect less than half that in your assembly.
I think their proposal will result in a center-of-cavity U factor (in metric for you) of closer to 0.4 w/m2k, and worse for whole wall.
In general, be skeptical of any insulating product that includes foil, as they often engage is such trickery. Radiant barriers have their place, but nine times out of ten are useless. Insist on proper foam or regular cavity insulation.
Hi Aedi
Thanks for taking the time, I was indeed suspicious thus my post!
For what it is worth, this certificate has some more specific data on the air gaps required.
Specifically, for a 2x6 stud being 140mm, one needs a 20mm air gap on each side so according to their own data a 105mm product yields 4.3 m2k/w (sorry can't recall the R value conversion) versus 4.2 m2k/w one fills the entire cavity with 140mm product with no air gaps.
http://www.insulation-actis.com/files/actis/pdfs/en/certificates/LABC/LABC-LABSS-certificate-EWWS462-ACTIS-Insulation-HYBRIS-072018.pdf
This article is somewhat out of date but touches on your concerns so may be of interest.
http://www.kdbinsulation.com/uploads/cms/LABC%20MG0190512%20Use%20of%20Multi-foil%20Insulation%20Products%20-%20Compliance%20with%20Regulation%207%20and%20Requirement%20L1_.pdf
While those numbers do clarify things, I am still very skeptical on how applicable they are to the real world. Radiant barriers function much differently from normal insulators, and will behave differently as a result. The also cannot be allowed to get dusty. I do not see any benefit they have over fiberglass batts, which is also light, compactable, and easy to cut, while being far less finicky, more durable, and almost certainly cheaper.
While it is possible to install these products while leaving air gaps on either side of them, I'm not sure that is the best idea for a few reasons. For one, you would need to maintain an air barrier on both sides of your assembly. You would also need to make sure the different air gaps cannot connect in any way, or energy will simply bypass your insulation. That essentially means air barriers between the air gaps as well. I am skeptical that the batts themselves will be an adequate air barrier, especially when installed by humans, but it is theoretically possible. I am also unsure of how one can go about ensuring the air gaps are present and kept to a constant depth during installation -- are some sort of standoffs used? Overall, this does not sound like a very constructible or durable wall.
As for the multifoil, it is really adding nothing to your assembly, especially with the use of battens over it anyway. Use a more typical vapor control product, and thicken the battens if you want more insulation.
HI Quinn -
just a quick note on conversions:
I keep this reference tabbed for metric/IP conversions: https://www.engineeringtoolbox.com/thermal-conductance-conversion-d_1334.html
Also, shiny metal surfaces of course have high reflectivity and low emissivity but only if they face an empty space. hence the boost in R-value but only with that space.
Peter
Thanks Peter
Think I've finally figured it out. (Thickness in metres) DIVIDED BY (thermal conductivity or λ in wm/k) TIMES 5.67 gets me my imperial R value.
Suffice to stay I'll be sticking with other more effective insulation materials.
Cheers