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    Posted By: paul johannsensources of ignition/heat are close (orrible gasses are released and it burns like hell)

    I'm surprised at this. The "double bubble" insulation I used (for reducing solar gains and for air infiltration remedy etc.) is rated as non-flammable (flame won't spread) as it's made of polyethylene and, as such, there are no "orrible gases" and it certainly doesn't burn like hell. Now foil-faced polyisocyanurate will give off all sorts of noxious gases and will probably burn strongly - but that's not the sort of insulation people think of when multifoils are discussed. Actually, over here in Canada, we don't see anything beyond 2 foil layers with "double bubble" being the most common foil faced insulation except for the rigid sheet material.

    Paul in Montreal.
    Thanks for that. We are probably a bit less pragmatic about things like fire in our stone houses as you guys with your lovely wood.

    Have just come back from a little test on a sample of triso-super 10 outside with a box of matches . Lovely product and very useful addition to the insulation stable but I would prefer sheeps wool and the treated pulp products.

    • CommentTimeMay 2nd 2007 edited
    To comment on paul johannsen's summary:

    >multifoil insulation is great if;
    the occupants are concerned about emf< Why so? I don't believe present multifoils contain any metal which could possibly shield emfs.
    >Used as one of the methods alongside more conventional and sustainable insulators< true temporarily while we have to work to the weedy performance certified for Thinsulex. When tested under the new under-development regime, end-2007, supplementary insulations will probably be proved unnecessary; however a multifoil/Cellotex combination will continue to work well, as conventional insulations are good under steady-state, crap under dynamically varying temps; multifoils the opposite.
    >it isn't stapled with lots of long steel staples (thermal bridges)< also endangers vapour/airtightness, if that's the intention.
    >used as part of filtration reduction measures< please clarify?

    >multifoil insulation is not so great if;
    The building is a heritage type airy high thermal mass transpiring buiilding> why?
    >You want a cavity for services routes< I find the inner counterbatten space (minimum 35mm) excellent for services.
    >Poorly installed< but easier than most to get right.
    >not overlapped sufficiently at building junctions< needs something a lot more effective than mere overlapping; forget taping; physical clamping carefully done is more like it.
    Posted By: fostertom>multifoil insulation is great if;
    the occupants are concerned about emf< Why so? I don't believe present multifoils contain any metal which could possibly shield emfs.
    I think thin films of aluminium do impede mobile phone signals.
    • CommentTimeMay 3rd 2007
    But as far as I know "aluminised" polyester or whatever, as used in current multifoils, doesn't include actual aluminium, or any metal?
    I've hear that before (perhaps from you?) but I'm not sure that I believe it. Polyester or whatever doesn't look shiny without a goodly layer of metal attached.
    • CommentAuthorMike George
    • CommentTimeMay 3rd 2007 edited
    I beleive the thickness of the 'metalised' coating is around 1-5 microns
    "Double bubble" certainly is aluminized. I had a massive spark when a live wire contacted it - scared the heck out of me!

    Paul in Montreal.
    Wrap your phone in some and see the signal disaappear.
    Polyester and thin film foils are commonly used in data installations and laboratories to shield equipment
    Work really well domestically for the myriad of emf stuff bouncing around.
    Last time I borrowed a spectrum analyser the airwaves were chocker with stuff.
    maximum induced emf I saw was 6mV again from phones.
    Maybe the bees need some?
    Much better to always do your own tests on any products.
    We should all satisfy ouselves and pass the confidence onto others.
    PS bob harris Earthdome is well up on all this too
    Happy shielding
    • CommentTimeMay 3rd 2007
    Posted By: biffvernonPolyester or whatever doesn't look shiny without a goodly layer of metal attached.
    Wow, I've been misinformed. I'm not sure if it's nice or nasty to live inside a shielded box. certainly good to keep out unnatural emfs but there's natural heathy stuff that we ought to receive, otherwise it's a bit like the 'airtight box' worry. What does shielding do to emfs originating inside the box - does it concentrate them/prevent dilution? And what about magnetic fields/oscillations - does it shield them too? And what about Wilhelm Reich - are we inadvertently building Orgone accumulators, for better or worse?!
    Even the see-through thinness of metal on a tinted window stops mobile signals. It cost a fortune to install systems that allow phones to work on trains with tinted windows.
    • CommentAuthorMike George
    • CommentTimeMay 12th 2007 edited
    Hi all. Please excuse the length of the post but I felt a synopsis of the thread to date would be beneficial before getting to the point

    There is currently much debate regarding the performance of multifoil as an effective insulation material. It has been claimed for some time by several manufacturers that their products provide an equivalent thermal performance to 200mm of mineral wool.

    The basis for these claims is a range of comparative tests, which involved the real life monitoring of two test vessels, which were measured under identical conditions. The only difference between the two vessels was the insulation, which was installed in the relative thicknesses indicated above.

    Since then, the tests have been replicated by BMTRADA, which resulted in certification supporting the manufacturers’ claims. In 2006, and after significant lobbying from insulation competitors, the Certificate was revoked resulting in a Building Control directive that the products were not to be accepted for use in line with the claimed performance.

    The rationale for this decision is that the comparative testing method is not recognised by any of the other UK accredited testing bodies, who all use the ‘official’ hot plate method for measuring thermal performance. When tested in this manner, multifoil does not achieve results anywhere near those indicated by the comparative testing.

    In trying to pre-empt the revoking of UK certification, various companies throughout Europe formed the CMM . They are currently trying to attain a ETA based on a CUAP which is an agreement between European standards bodies on test and approvals methodology. This methodology is so far undecided and all interested parties have been invited to propose and agree a common test procedure.

    Historically, multifoils have performed well with comparative testing so not surprisingly, this is likely to be proposed. In order for this to be acceptable however, it was thought that other supporting evidence would be necessary.

    With this in mind, an initial research proposal was proposed to a well known multifoil manufacturer. The proposal was to duplicate either previous and/or ongoing test vessels using dynamic thermal simulation software, though this has not been taken up by the company involved due to insufficient funding.

    Nevertheless, an initial pilot study which I have carried out with the help of a final year student has given some interesting results.

    The biggest limitation is that we have needed to configure our own bespoke multifoil material, as manufacturers to date have been unwilling to provide us with any information. This only goes so far in representing an actual product but in any event the indicative u-value of the materials [which could in theory be manufactured] is [0.5W/m2K]

    I have to confess that I am struggling to explain the results. I can provide further information but please don’t ask me to try and explain the physics of what is happening. Comments and curses please…..no rotten eggs or tomatoes. Initial report here

    1. Confederation of Multifoil Manufacturers
    2. European Technical Approval
    3. Common Understanding of Assessment Procedure
    • CommentAuthorsteve mac
    • CommentTimeMay 13th 2007
    I have also installed iso super 10 in my loft .I purchased the product in 2005 before I discovered its properties did not stand up tothe manufactures stated insulation properties.I supported the foil by installing 100 mm rockwool between the rafters, however, I have concerns as I have now read in this forum that mice find the foil enjoyable. I have'nt yet finished completing the job,however, I have on my list of things to do is completly lime morter the stone joints on my Brittany farm house where I suspect they crawl up and emerge into the rooms.
    • CommentAuthorCvaey78
    • CommentTimeMay 13th 2007
    Having followed the multifoil debate for some time and having the added benifit of working in the industry for some time, I am amazed how the multifoil manufacturers are STILL alowwed to claim the results that they do. Yes in perfect lab conditions the materail does perform as claimed, But i have yet to find a a job that has been completed to best practice (this is no disrespect to builders, but it was designed for use in space and installed by scientists). As a stand alone insulation material it falls far short of its claims. If you puncture it to hold in place then it affects the performance, if you do not seal it correctly then this has a major impact on its performance, if it gets dusty it effects its performance.... and so on.
    All multifoils should be used with a n other insulating material to effectivly reduce the overall thickness of insulation needed to do the job.

    hope this helps

    Hi Cvaey, I am little confused by your post. When you say multifoil performs as claimed under perfect lab conditions are you referring to my thermal simulations?
    • CommentAuthorRBean
    • CommentTimeMay 14th 2007
    This is an excerpt from a pending advisory from Natural Resources Canada,

    "As a result of countless inquiries from the general public, building contractors and building professionals concerning claims made by manufacturers of foil-faced bubble insulation (FFBI) products, Natural Resources Canada (NRCan) has prepared this paper dealing with the effective thermal resistance (RSI/R value) of these and other reflective types of products for the purpose of energy modeling under its energy efficiency housing initiatives."

    We received the draft version last week and anticipating permission to release final document Thursday or Friday of this week.

    Will provide link in due course.

    Journal of Indoor Environmental Quality
    Hi RBean, that's very interesting, are you referring to dynamic simulation modelling?
    • CommentAuthorRBean
    • CommentTimeMay 14th 2007
    The advisory will specify the R values to be used in its' HOT2000â„¢ software.

    This is the software link:
    Thanks again RBean, I have inquired if a demo copy of the HOT2000 software is available from NRC. I would also be interested in any technical papers which discuss the way in whch the software performs simulations. Any further information you could offer would be much appreciated.
    Anyone can download Hot2000 - you don't need a "demo" version at all. If I recall correctly, a lot of the algorithm development that's in hot2000 was performed at the University of Strathclyde - certainly the newer hot3000 is based on this work. RBean doesn't give the best link. Here's the link to the download page:


    You have to register your email address and then you're free to download.

    Paul in Montreal.
    Marvellous! thanks Paul, I will check it out. Is it difficult to get to grips with?

    no, it's pretty easy to get going with - there are some examples included that will help. I was able to put in a model of my 109 year old brick/stone house, complete with blower door air leakage measurements and a GSHP - the resulting estimates are within about 5-8% of actual measured performance over the past 20 months.

    Paul in Montreal.
    Great thanks, I will have a look and hopefully won't be pestering you with too many questions!
    Paul, I have the software now and it does seem very user friendly. Can I ask you a further question? If you were to input your own wall or roof configuration, [multifoil for example] would this be defined by R-value alone? or are other physical [material] properties such as Density, Specific heat capacity etc also inputted?

    there's no direct input of material properties such as specific heat capacity, density etc. There is a global "thermal mass" property that can be set on a building which I've found only affects the percentage of solar gain that is usable by the building. I think some of the materials listed that can be used to "build" wall and roof sections may be modeled in some way that's more complex than just their thermal resistance, but I'm not sure. Note also (though it's probably obvious) that you need to make sure your units are correct for R-value if you're working in metric (RSI is the reciprocal of U value). Other than that, if you are "building" wall and roof sections, make sure you include every single layer including any air gaps. You may find that not every material is listed - however most are close enough that you should have reasonable results. As for multifoil, you'll have to guess an R-value! I gather that's the secret technique that some manufacturers use anyway ;)

    You can contact me directly at the email address that's listed in my user profile if you like.

    Happy hot2000 modeling! I've found it all quite addictive!

    Ah, I was hoping that it would model thermal mass, as I want to compare results that I am getting using TAS. Thanks for all of your help, I will have a play with Hot2000 and see what I can come up with.
    Hi Mike,

    what is TAS? There is some modeling of thermal mass within hot2000 - but it appears to be somewhat coarse-grained. I don't honestly know if the wall material database includes thermal mass in the modeled properties beyond the setting of the global "thermal mass" parameter. One thing I did find, though, is that usable solar gains go up quite a bit if one selects single glazing and "high thermal mass"!


    Tas is one of the better thermal simulation softwares [in my opinion] in the UK. You can get a free demo version here: , though I doubt you'll want to stretch as far as the 3 or £4000 for a comercial version

    There is also a very good paper comparing simulation softwares [TAS included] here: http://www.eere.energy.gov/buildings/tools_directory/pdfs/contrasting_the_capabilities_of_building_energy_performance_simulation_programs_v1.0.pdf
    Hi again all, Is there anyone out there with any constructive comments about my comparative multifoil modelling? After all It is not so very long ago that many here were proclaiming 'multifoil is dead' and ridiculing anyone who dared oppose their explanation of why the hot box is the only way to asses the themal properties of insulation. :devil:

    Is this kind of assessment a possible way forward in the debate? Does it come closer than a hot box in duplicating real life? Are my results flawed in some way? :cry: Is there anyone interested in duplicate them for me using the same [or other ] software. C'mon guys where are you? :middlefinger:
    • CommentAuthorbiffvernon
    • CommentTimeMay 19th 2007
    Mike, I really don't have anything to say about the modelling because I don't know enough, but have you got a theoretical explanation as to why the inner foil layers might do anything useful. A long time ago I suggested that after one (or maybe two) foil layers, the laws of diminishing return strike with such a vengance one might as well use layers of snake oil instead of aluminium. No-one, afaik, has convincingly countered that yet.
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