Green Building Forum - Multifoil Insulation

Multifoil Insulation

Mike George — Mon, 19 Jan 2009 11:59:28 +0000

Yes, yes, but the recent debate is in relation to air tightness, not the old thermal conductivity chestnut.

Would you agree that air tightness reduces heat loss, and that this type of multifoil is rather good at doing so?

Multifoil Insulation

James Norton — Mon, 19 Jan 2009 12:23:38 +0000

Posted By: biffvernonThermal performance â€” when combined with other types of insulation

I caught that one, you could get a BBA cert for anything as an insulator then? as long as "combined with other types of insulation"

"new all improved 'Mars bar wrappers', space age insulation (Mars - space...? eh..? eh...? ... sorry...)... Certified to archive a U-value of 0.1!...."

(small print: "Depending on the construction method and when combined with other types of insulation...")

Seems to me that Actis et al were have tried to take on the David vs Goliath, Linux vs Windows sort of mantle we all love to stick up for. Yup no doubt in my mind that Kingspan + Celotex will make insulation out of their Grannies if it would flog a few more sheets, but that doesn't automatically make Actis not bent as butchers meat hooks when it comes to testing etc. You never know there might be miracle cures out there and we should keep an open mind but to be honest I don't think its likely (no I can't can;t support that statement with scientific evidence!) - till then it remains easy said than done to save the world!

J

Multifoil Insulation

Timber — Mon, 19 Jan 2009 13:17:08 +0000

Multifoil Insulation

fostertom — Mon, 19 Jan 2009 13:22:03 +0000

Posted By: James Nortonbent as butchers meat hooks when it comes to testing etc

Can't speak about Actis, but no-one who's had chats with Paul Mitton would doubt the integrity of his extensive multifoil testing and development. As Tech Director of little Euroform he was stepping in where wealthy Actis should have lead, in the CMM (Confed of (UK) Multifoil Manufacturers)'s scientific campaign to get the European accreditation organisations to introduce methods capable of testing multifoils under the 'real life' conditions in which they excel. As a result, against all the non-scientific influence that the conventional insulation manufacturers could muster, CMM's scientific case was accepted and a 5-yr programme was instituted to build 13 very expensive dynamically-varying temp test rigs across Europe (the flaws in the trad steady-state hotbox methodology having been demonstrated). Also SIG (Sheffield Insulations) paid Â£8m to acquire Euroform - the only insulation manufacturing co. (as distinct from re-processor/distributor) they currently own. No amount of 'skeptic' rhetoric and suggestive slander will alter either the statement of 1st sentence above, nor the two expensive statements-of-faith of the last 2 sentences above.

Multifoil Insulation

Mike George — Mon, 19 Jan 2009 13:32:35 +0000

Thanks for the positive question timber. The test is inaccordance with BS EN 12114, so presumably pukka. Also, in terms of Certification, BBA is pretty well respected, one of the previous critisisms of multifoil being that they had never achieved one.

No, I don't think extrapolation is fair in this case, but then you would have to be out by a factor of 100 for this element of construction to be the cause of failing a domestic pressure test requirement of 10m3/m2/hr @50Pa.

Any way you look at it, the airtightness is very VERY good.

So to the critics, cmon guys, admit it. The method recomended in the BBA will have superior performance to other insulations having the same [HOT BOX tested] u-value, but also having greater [poorer] air permiable properties. The only question is by how much? Anyone care to take a stab at it?

Multifoil Insulation

Timber — Mon, 19 Jan 2009 13:45:09 +0000

Multifoil Insulation

Timber — Mon, 19 Jan 2009 13:48:21 +0000

Woops, double post!

Multifoil Insulation

Mike George — Mon, 19 Jan 2009 13:59:34 +0000

Posted By: TimberSo, the out and out air leakage performance of the origional TRADA tests is unknown.

Probably known, but not published. The GenX material is also completely different to that originally tested [actis?] by TRADA, so not really fair to draw a comparison.

I should declare that I have done some consultation work for Euroform in the past, but only Dynamic Simulation work, with results which are not yet certified in any way or for that matter fully understood.

Multifoil Insulation

James Norton — Mon, 19 Jan 2009 15:19:16 +0000

Posted By: fostertomskeptic' rhetoric and suggestive slander

Oh Tom, do calm down I was only teasing and anyway the first part of my thread was about the dubious wording of the thermal performance section of the cert rather than the product itself.

I'm sure Paul is a lovely chap, the point I was making is that they're all out there to make money and although admirable to go up against Celotex and Kingspan (the comments I made about whom I notice you seem happy with: "...make insulation out of their Grannies if it would flog a few more sheets..."!) - this alone should not deceive us. If it stacks up then great and/or if it changes the way we look at modelling and regulating heat loss in buildings then even better!

Its good to be a sceptic, as long as you are even handed in your scepticism, which I likle to think I am - (see earlier comments about both grannies and meat hooks)

Seriously(!) though, round of applasue as the thread tops 450, shall we have a party at 500?

Keep up the good work chaps.

J

PS is it slander to (falsely) accuse someone of slander?

Multifoil Insulation

Mike George — Mon, 19 Jan 2009 17:08:14 +0000

Posted By: James NortonSeriously(!) though, round of applasue as the thread tops 450, shall we have a party at 500?" alt="" src="https:///newforum/extensions/Vanillacons/smilies/happy/clap.gif" >

Are you buying? where to?

Multifoil Insulation

fostertom — Mon, 19 Jan 2009 17:48:44 +0000

Posted By: James NortonOh Tom, do calm down

Sorreee

Posted By: James NortonIts good to be a sceptic

It's skepics I have doubts about

Posted By: James Nortonyou seem happy with: "...make insulation out of their Grannies if it would flog a few more sheets..."

True, and I'm similarly unimpressed with Actis, the original BBA 'twin shack' sponsors. The point is, amongst a dubious bunch, I take Paul Mitton's work seriously - enough to be convinced there's something genuine there, and therefore to have given energy to thinking through how and why multifoils might achieve what is claimed, to my satisfaction. My own understanding, that I've offered here several times - might do it again, if anyone intetested.

Multifoil Insulation

James Norton — Mon, 19 Jan 2009 17:54:50 +0000

Posted By: fostertomMy own understanding, that I've offered here several times - might do it again, if anyone intetested.

If you can offer it a mere 31 more times Mikes going to buy us all a drink!

Seriously (again) though one of the real issues with this debate is the potential impact on a wider revisit of how we measure the heat loss of buildings and the impact on the basic U-value as not necessarily (to understate) the best method of understanding how much energy a building actually uses in practice. This chimes in with many other strands of recent debate in te real world as well as the forum.

J

Multifoil Insulation

biffvernon — Mon, 19 Jan 2009 17:58:15 +0000

Posted By: Mike GeorgeYes, yes, but the recent debate is in relation to air tightness, not the old thermal conductivity chestnut.

Would you agree that air tightness reduces heat loss, and that this type of multifoil is rather good at doing so?

I've never debated it's airtightness, but if airtightness is what you want then it's cheaper to use a sheet of polythene. If you want to combine airtightness with insulation then use bubblewrap. My point has always been that the internal layers of foil in a multifoil are are very expensive way of adding very little insulation. This BBA Certificate does not alter that point.

Multifoil Insulation

Mike George — Mon, 19 Jan 2009 19:27:47 +0000

Posted By: biffvernonI've never debated it's airtightness, but if airtightness is what you want then it's cheaper to use a sheet of polythene. If you want to combine airtightness with insulation then use bubblewrap.

Aint necesarilly so. Here's a suggestion -the more layers there are, the more convoluted the airpath to the ouside, fill the spaces between the membranes with fluffy stuff - better again - common sense - innit

Posted By: biffvernonMy point has always been that the internal layers of foil in a multifoil are are very expensive way of adding very little insulation.

Not proven, one way or the other. Go directly to the start of the thread, do not pass go, and do not collect Â£200 [unless the drinks are on you]

Posted By: biffvernonThis BBA Certificate does not alter that point.

It alters nothing, except that the owners of the Certificate have decided that if you cannot beat them, join them. Ie they have complied with the BR443 method [Hot plate] of measuring thermal conductivity.

Suggest we give credit where its due.

Multifoil Insulation

fostertom — Mon, 19 Jan 2009 20:24:05 +0000

Posted By: Mike GeorgeBBA is pretty well respected, one of the previous critisisms of multifoil being that they had never achieved one

Thinsulex already have - this Euroform one just replicates Thinsulex's - doesn't it? (not having read the new one)

Multifoil Insulation

fostertom — Mon, 19 Jan 2009 20:34:56 +0000

Posted By: Mike George
Posted By: biffvernonMy point has always been that the internal layers of foil in a multifoil are are very expensive way of adding very little insulation.

Not proven, one way or the other

certainly not by Biff! whose spreadsheet exercise, as I remember it, never got completed, and only accounted for the 5% of radiant that got through from layer to layer to layer, so obviously got rapidly into diminishing returns (5% of 5% of 5% = 0.0125%), whilst ignoring the 95% that got reflected back, then re-reflected forward, of which 5% got through and 95% went back, came forward again ad infinitum. Once the 95%'s are accounted for and summed, the result is near-linear temp decline from layer to layer to layer - in other words every layer plays a near-equal part, and the more layers the greater the total resistance. Of course, like any insulant, additional layers/additional thickness has diminishing effect, but that's 'normal' diminishing returns quite different from the exponentially vanishing returns that Biff's been aledging for the inner layers.

Multifoil Insulation

Mike George — Mon, 19 Jan 2009 20:35:43 +0000

Posted By: fostertomThinsulex already have - this Euroform one just replicates Thinsulex's - doesn't it? (not having read the new one)

Yes, pretty much. Not sure about the level of airtightness though. Will check when I get five

Multifoil Insulation

biffvernon — Mon, 19 Jan 2009 21:46:49 +0000

Er, no Tom. You've not understood. And Mike, airtightness is a red herring. Nothing to do with the essential feature of multifoil. All the BBA cert says is that multifoil is fine so long as you use it with something else - long-johns, base layers, hot-water bottle, the choice is yours. The BBA cert does not say incoporating extra layers of foil within an insulator is good value for money.

Multifoil Insulation

Mike George — Mon, 19 Jan 2009 21:52:41 +0000

I give up! The BBA doesn't say about value for money, but it does say airtightness of 0.1m3/m2/hr@50Pa, which is 100 times better than current Part L requirement [10] for dwellings.

Edited, I dont give up after all

Typically around 40% of heat is lost via air infiltration, so it doesn't take a genius to work out how much can be saved at the levels quoted. Now I am not saying that a whole house rate of 0.1m3/m2/hr is possible, but IF a house could be designed encapsulated in multifoil, then the savings through air losses would be staggering when compared to other [more leaky] forms of construction.

Forget the argument about u-values, they don't allow for air infiltration and are irrelavant in this context.

Multifoil Insulation

fostertom — Tue, 20 Jan 2009 01:46:53 +0000

Posted By: biffvernonTom. You've not understood

Aha! we have engagement! so - gonna explain what I haven't understood?

Multifoil Insulation

biffvernon — Tue, 20 Jan 2009 07:58:39 +0000

Posted By: Mike George
Forget the argument about u-values,

OK, let's forget the argument about u-values. Who would buy insulation just for it's u-value? What a silly notion.

Multifoils are great for draught-stopping. Hurraaaahhhh!

Multifoil Insulation

James Norton — Tue, 20 Jan 2009 08:47:40 +0000

Posted By: Mike GeorgeForget the argument about u-values... ...(they) are irrelavant in this context.

Don't give up Mike,

I was just having a laugh, its a good point about the infiltration rates, I suppose the key thing re BBA is that is is not necessarily certifying the material / product as an insulant?

However as a "draught stopper" alone they are horrendously expensive...?

J

PS Anyone any idea how I might actually make insulation out of grannies...?

Multifoil Insulation

Timber — Tue, 20 Jan 2009 09:31:03 +0000

Multifoil Insulation

biffvernon — Tue, 20 Jan 2009 11:20:36 +0000

Yes. Referring back to the start of this interminable thread, I started by being bedazzled by this space-agey material but was sensible enough to consider the theory behind it before spending money. I could not reconcile my theoretical understanding of the physics with my ethusiasm for the product. So I did an experiment. Experiment and observation supported the theory and not my prejudice so I had to change my opinion. Others have conducted more sophisticated experiments and yet others have investigated the theory further.

We are left with very expensive draught excluder.

Multifoil Insulation

James Norton — Tue, 20 Jan 2009 13:06:53 +0000

Posted By: TimberPerhaps instead of arguing, you could make some of your own test sheds and do some of your own testing.

this could be difficult living in a maisonette with no garden or shed, however other issues are also going to be a problem, such as sourcing the grannies...

J

Multifoil Insulation

fostertom — Tue, 20 Jan 2009 13:28:39 +0000

Posted By: biffvernonI could not reconcile my theoretical understanding of the physics with my ethusiasm for the product. So I did an experiment. Experiment and observation supported the theory and not my prejudice so I had to change my opinion.

I'd really appreciate it, to have you run through that process, or provide links to the (old) forum. I remember there was the cafetiere experiment, and the spreadsheet model. Was there more?

Much later Tony (I think) re-ran the experiment, modified to meet the crits made of your original one. Others too.

Perhaps it's time for all those who've done their own practical or theoretical investigations into multifoil, to join in a concentrated re-summary of what each of us thinks we discovered.

Multifoil Insulation

Noyers — Tue, 20 Jan 2009 14:08:08 +0000

I think some of you could join the "Royal Society for the Protection of Entrenched Views".
This seems an argument that could last longer than any mere building.
Thankfully you must all be so busy building sheds, hot boxes and cafetieres that you have no time to become really annoyed.
Sorry, just helping the thread along to the 500 mark.
Seriously, would love to see a synopsis of the current thinking.

Multifoil Insulation

James Norton — Tue, 20 Jan 2009 14:12:30 +0000

Posted By: NoyersSorry, just helping the thread along to the 500 mark.

A worthy goal.

J

PS

Posted By: NoyersSeriously, would love to see a synopsis of the current thinking.

By the time that kind of agreement is reached we'll be at 1000!

Multifoil Insulation

johnz — Sun, 25 Jan 2009 09:52:03 +0000

Just to muddy the waters, any views on the 'Breather foil' timber frame membrane? (being touted as the equivelent of adding 25mm celotex to your wall system) from what I see it 'breathes through the overlaps that arent 'tight' due to the bubblewrap.

Multifoil Insulation

fostertom — Sun, 25 Jan 2009 12:13:24 +0000

Good god