Green Building Forum - Multifoil Insulation

Multifoil Insulation

SteamyTea — Sun, 02 Aug 2015 21:37:38 +0100

I was going to upgrade to Windows 10 till I read this:

http://www.joe.ie/news/man-updates-to-windows-10-wakes-to-find-porn-slideshow-playing-on-repeat/506714

They will try anything to sell things these days.

Multifoil Insulation

fostertom — Fri, 13 Nov 2015 14:39:07 +0000

Current on the Actis website:
http://www.insulation-actis.com/pdf/45pdf13.pdf
apparently reinstating the BM Trada Certificate that Triso Super 10+ is equiv to 210mm of 0.04 min wool, by the in situ comparative 'twin shacks' test method.

"As there are currently no ISO or BS EN testing standards designed for innovative multifoil
insulation products, this new UKAS accreditation gives further confi dence to local Authority
Building Control Bodies to accept independent certifi cation for insulation products"

"TRISO-SUPER 10+ IS THE FIRST PRODUCT CERTIFIED BY BM TRADA CERTIFICATION IN
ACCORDANCE WITH THE NEW UKAS ACCREDITED BUILDING INSULATION PRODUCTS SCHEME"

What of the 2005 BRE report on the original 'twin shacks' test of Tri-Iso Super 9 which discredited the BM Trada certificate and led to its removal as authority for Tri-Iso's effective U-value?
http://www.insulation-actis.com/news.php?p=3&l=3&rub=5&vert=4&typenews=4

"ACTIS response to 2005 BRE report

16-11-2007

The Building Research Establishment (BRE) drafted a report in July 2005 claiming that the in-situ performance of TRI-ISO SUPER 9 was not in line with published values.

ACTIS was alerted to the existence of this draft report prior to its general dissemination, and immediately arranged for an inspection and audit of the site by independent thermography specialists, ALBA Building Sciences (ABS), in order to understand the circumstances which led to the apparent substandard performance of the TRI-ISO SUPER 9 product in the buildings concerned.

Thermal images taken by ALBA Building Sciences, using an infrared camera, revealed that the product had been installed incorrectly. The images showed heat loss and cold air infiltration between the sheets of insulation and between the insulation and the structure of the building, which would not ordinarily occur if the product had been correctly installed. We should emphasise that the images showed cold air infiltration at the edges of the product and not in the centre, indicating heat loss at the extremities of the product rather than through the fabric of the product itself. ACTIS suspected that the product had been installed incorrectly.

The wall was demolished and this suspicion was confirmed: as the colour photographs in the ALBA reports clearly show, the installation did not comply with the standard ACTIS fitting instructions for its multi-foil insulation products. ACTIS subsequently had the insulation refitted in accordance with these fitting instructions, overlapping all joints, stapling back to the timber structure, and covering joints with foil backed tape. ALBA Building Sciences then repeated their tests, which showed the thermal performance of TRI-ISO SUPER 9 to be in line with published values.

Download the full ABS reports, complete with pictures and thermographic images of the site, here:
ALBA Building Sciences ACTIS report 1 (report no. 25035) First study
ALBA Building Sciences ACTIS report 2 (report no. 25038) Second and third (post correction) studies.

As a result of the thermographic images and tests carried out by ALBA, ACTIS considers the 2005 BRE report to be both flawed and misleading, and would advise that it be disregarded.

Whilst ACTIS understands that the BRE was not responsible for the installation of the TRI-ISO SUPER 9 product in the buildings concerned, ACTIS also understands that the BRE did not monitor or control this installation. It should be emphasized that the BM TRADA certification for the product has been given on the basis that the manufacturer's guidelines are followed.

It should perhaps be noted that ACTIS has invited the BRE to repeat the tests, at ACTIS' own expense, but this time following the installation guidelines for these products. ACTIS has also invited the BRE to inspect the test chalets at the TRADA site used to test the TRI-ISO SUPER 10 product; to witness the installations, the rigour of the testing and the correct installation method to be followed. Both of these offers have been declined.

As with many, if not all, thermal insulation products, correct installation is essential in order to achieve optimum thermal performance."

Multifoil Insulation

Triassic — Mon, 16 Nov 2015 07:35:12 +0000

Posted By: fostertomBRE did not monitor or control this installation.

Would the man on the Clapham Omnibus know what to look for in terms of correct installation? Snake oil!!

Multifoil Insulation

fostertom — Mon, 16 Nov 2015 10:07:49 +0000

How about following the instructions supplied?

Multifoil Insulation

ringi — Mon, 16 Nov 2015 18:33:53 +0000

Posted By: fostertomHow about following the instructions supplied?

Have you EVER been able to get a builder to do this?

Multifoil Insulation

Beau — Mon, 16 Nov 2015 18:51:09 +0000

Posted By: fostertomHow about following the instructions supplied?

Spot on Tom

It's pretty basic. 25mm gap each side of the foil and tape the joints. We did this and it works to our expectation.

Multifoil Insulation

Triassic — Mon, 16 Nov 2015 18:55:57 +0000

Looked on the web site for installation instructions for Triso Super 10+, can't find any mention of the product or how to correctly install it.

Multifoil Insulation

Triassic — Mon, 16 Nov 2015 18:57:57 +0000

Posted By: Beau25mm gap each side of the foil

Are you sure, why a gap?? I thought gaps in insulation were a no, no.

Multifoil Insulation

Beau — Mon, 16 Nov 2015 19:05:38 +0000

Posted By: Triassic
Posted By: Beau25mm gap each side of the foil
Are you sure, why a gap?? I thought gaps in insulation were a no, no.

That was the instructions for Triiso super 9 back in the day. Not sure of the reasoning but did as instructed with no regrets. Some guidance on this page for Triiso 10 http://www.insulation-online.com/actis-triso-super-10-plus-multi-foil-insulation.html

Multifoil Insulation

DarylP — Mon, 16 Nov 2015 19:18:10 +0000

The 'multi-foils' claim their performance partly derives from the low-emissivity still air spaces either side of the product, when installed correctly.
Without them, the R-value drops..... buyer beware.....

Multifoil Insulation

gyrogear — Mon, 16 Nov 2015 22:18:03 +0000

"25mm gap each side of the foil"

I suspect it said, "air space"

gg

Multifoil Insulation

Beau — Mon, 16 Nov 2015 23:07:31 +0000

Posted By: gyrogear"25mm gap each side of the foil"

I suspect it said, "air space"

gg

Yes your probably right but you get the gist

Multifoil Insulation

fostertom — Tue, 17 Nov 2015 10:11:14 +0000

Multifoils work by being v reluctant to radiate heat across an air gap, because of its multiple shiny surfaces having v low emissivity.

That's the several shiny surfaces that face another ditto within the multiple layers of the quilt,
and the 2 outermost shiny surfaces that face an ordinary building-material surface.

Radiation happens across an air gap, not between surfaces that are in contact.
So if the outermost shiny surface touches the ordinary building-material surface, then there's no radiation there for the multifoil to resist, so a significant %age of the multifoil's functional shiny surfaces are disabled.

That's why there must be at least a tiny air gap between the multifoil's 2 outer faces, as installed, and the soild it faces.

As multifoil is typically 30-something mm thick, this suggests to me that the usual recommended 2x25mm cross-battening (or 1x25mm on 'empty' studwork) isn't thick enough - 2x38 or even 2x45 would gurantee that nothing touches, bearing in mind that the multifoil doesn't 'hang' vertical but gets pushed fully to left or right, depending whether it's locally being pushed sideways by the battening, or the cross-battening.

It's true that such air spaces are moderate no-no's with insulation. Note that the airspaces do not provide air passages parallel with the direction of heat flow, but are oriented crosswise to the heat flow. The former would be disastrous; the latter are merely inadvisable, and on the face of it actually add to overall insulation.

The danger with such air spaces crosswise to the heat flow, is that they provide a path for air to convect from areas of good effective insulation, to areas of lower insulation - that might be just a corner area, which always loses more heat due to heat-flow geometry. So the recommendation is that crosswise air spaces are OK, even helpful, as long as they're limited in extent - say 1m in ea direction.

It's true you can't readily create those 1m x 1m limits with the required air gaps with multifoils.

Multifoil Insulation

djh — Tue, 17 Nov 2015 10:27:57 +0000

Posted By: fostertomMultifoils work by being v reluctant to radiate heat across an air gap, because of its multiple shiny surfaces having v low emissivity.

That's the several shiny surfaces that face another ditto within the multiple layers of the quilt,
and the 2 outermost shiny surfaces that face an ordinary building-material surface.

Radiation happens across an air gap, not between surfaces that are in contact.
So if the outermost shiny surface touches the ordinary building-material surface, then there's no radiation there for the multifoil to resist, so a significant %age of the multifoil's functional shiny surfaces are disabled.

That's why there must be at least a tiny air gap between the multifoil's 2 outer faces, as installed, and the soild it faces.

If you reread this, can you see the contradiction? There are lots of shiny surfaces, and it's apparently absolutely essential that the two on the outside have a gap, but somehow, miraculously, the ones on the inside function without the gap. So how does that work then?

Multifoil Insulation

DarylP — Tue, 17 Nov 2015 10:40:42 +0000

... who says they 'function'.... ?

Multifoil Insulation

fostertom — Tue, 17 Nov 2015 10:58:32 +0000

The air gap can be microscopic - that's enough. The wadding between isn't 'solid' - it presents numerous point-ends and short curving-away line-contacts to the shiny surface, leaving nearly all airspace between.

Come to think, why don't the MF manufs put a layer of the wadding on the outside, so even if that's touching something solid, as far as the outer shiny surface is concerned it's still seeing air space?

Multifoil Insulation

owlman — Tue, 17 Nov 2015 11:23:47 +0000

Posted By: fostertom.............

Come to think, why don't the MF manufs put a layer of the wadding on the outside, so even if that's touching something solid, as far as the outer shiny surface is concerned it's still seeing air space?

Would it perhaps work better if you ran a strip of self adhesive foam, ( maybe expanding), tape along the rafters or battens first as a cushion.

Multifoil Insulation

fostertom — Tue, 17 Nov 2015 13:18:05 +0000

You mean, to reduce the effect of the MF touching the battens/crossbattens or battens/unfilled raftering (or studwork)? That's in addition to it touching the extg wall, plasterboard etc?

Yes, would help, with that %age reduction of insulativeness over that small %age of proportional area - but would have to be not just any old foam, but the same kind of wadding as the MF interior, prob specially chosen for its ability to space the foils apart with minimal contact.

Multifoil Insulation

djh — Tue, 17 Nov 2015 13:59:33 +0000

Posted By: fostertomCome to think, why don't the MF manufs put a layer of the wadding on the outside, so even if that's touching something solid, as far as the outer shiny surface is concerned it's still seeing air space?

Indeed, then the product would be simple to install and always work and be easy to see its benefits. Oh wait ...

Multifoil Insulation

SteamyTea — Tue, 17 Nov 2015 21:38:21 +0000

Before long, we will all be standing by a window on a cold night trying to work out the radiation losses. Then compare them to an internal wall.

I shall jump now

Multifoil Insulation

wookey — Mon, 23 Nov 2015 03:37:25 +0000

You would like to think that the BRE would install things according to the destructions when doing tests for certification purposes. Anyone read the reports for the details?

Multifoil Insulation

collonach — Mon, 11 Jan 2016 17:44:54 +0000

What does the Passiv Haus Accreditor think of multifoil?

Multifoil Insulation

ringi — Mon, 11 Jan 2016 18:11:30 +0000

Posted By: wookeyYou would like to think that the BRE would install things according to the destructions when doing tests for certification purposes. Anyone read the reports for the details?

Should they not install it in the way it is most likely to be installed by builders in real life....

Multifoil Insulation

DarylP — Mon, 11 Jan 2016 19:40:09 +0000

... what, badly?

Multifoil Insulation

DarylP — Mon, 11 Jan 2016 19:44:07 +0000

On a more serious note, I am not sure how PHPP verifies U-values, are they to BS EN ISO 8990?
If so, Multifoil would not have a very high thermal resistance?

Multifoil Insulation

djh — Mon, 11 Jan 2016 21:21:50 +0000

Posted By: DarylPOn a more serious note, I am not sure how PHPP verifies U-values, are they to BS EN ISO 8990?

I can only speak for PHPP 2007 and that is EN 6946 with conductivity following the national norm or the technical approval of th governmental authority in charge.

I know a common mistake in PHPP is to use the wrong U-value. I didn't pay close attention but I think it's a case of the manufacturers publishing a bold figure that is meaningless or optimistic and burying the real one in the small print.

Multifoil Insulation

DarylP — Tue, 12 Jan 2016 07:18:53 +0000

djh,

....interesting, if so then the R value for a 30mm 'multifoil' should be about 0.9
and adding in the low-E still air spaces either side of the product
gives a U-value 0.43W/m2k

Multifoil Insulation

fostertom — Tue, 12 Jan 2016 09:28:40 +0000

http://www.insulation-actis.com/pdf/45pdf13.pdf

Renewed (25.10.11) certification that Triso-Super10+ "has an in-situ thermal insulation performance equivalent to 210mm of mineral wool". Methodology is a reformulated, negotiated and agreed version of the 'notorious' twin-shacks certificate of 1990-something.

Multifoil Insulation

djh — Tue, 12 Jan 2016 09:51:06 +0000

That isn't according to the PHPP required standard that I stated AFAICT but I really don't follow the saga very carefully.

Multifoil Insulation

fostertom — Tue, 12 Jan 2016 10:11:07 +0000

Point is, the 'discredited' methodology has been quietly reinstated, by agreement (with whom, I'm not sure) some years now - the validity of the principle of insitu testing, even comparative ditto, is reconfirmed, as alternative to insisting on artificial (never in real life) steady-state abstraction via hotbox.