Multi Layer foil insulation

[Mark]

The gas in aerogels is air. The clue is in the name.

OK. I took the name as being a reference to aerospace technology - I've obviously been reading too much marketing blurb.

 

[Penners]

The PUR and PIR foam boards are inflated with something other than air, such as pentane.

I thought pentane was a liquid.

(OK - I looked it up)

 

[biffvernon]

Ah, curious. I notice that the boiling point of Pentane is listed as 36.1 C, quite a warm day. Maybe the pentane is mixed with another hydro-carbon, lowering it's partial pressure and getting to the boudaries of my ability to remember O'level chemistry.

 

[Me!]

The PUR and PIR foam boards are inflated with something other than air, such as pentane. This insulates better than air but it is unclear how much of it will have leaked out and been replaced by air after a few decades.

I hope it has all leaked out long before it gets anywhere near me, pentane is highly flammable with a flash point of -49C!

 

[Penners]

Hmmm - boiling point of 36.1C, flash point of -49C. This strange substance apparently combusts some 85 degrees colder than it boils! :?

 

[biffvernon]

Nevertheless, a quick google for pentane insulation will reveal much confirmation of the use of pentanes in insulation board.
Here's one: http://www.alumashield.com/GS/

 

[Me!]

Hmmm - boiling point of 36.1C, flash point of -49C. This strange substance apparently combusts some 85 degrees colder than it boils! :?

That's not as strange as it sounds though, just think of petrol as an example. If you have a bucket of petrol at room temperature it doesn't boil, but it you light it (and please don't try this at home children!) it certainly burns. See - http://en.wikipedia.org/wiki/Flash_point and http://en.wikipedia.org/wiki/Autoignition_temperature

However I still don't understand how a giant crunchy-bar with all it's bubbles full of pentane can't be extremely dangerous if I fix it to my house? In Biff's last link, it does say "Other pentane considerations include workplace safety as related to precautions in mitigating flammability risks of HC blowing agents during the production process, which is not related to end user application." So does that suggest that all the pentane has gone from the end product before it leaves the factory?

 

[biffvernon]

No, the pentane is an important ingredient in the finished product. It's what makes the board a particularly good insulator. Maybe it is like a giant crunchy-bar, with the inflamable gas safely locked up in the cells. Racing cars have fuel tanks that are crunchy-bar like, which is why they don't explode when the car gets crunched.

 

[citizensmith]

Pentane - as a hydrocarbon, sounds to me like it should be a very potent greenhouse gas, up there with methane at 20x the efficiency of Carbon Dioxide. I can imagine similar problems like there were with CFCs escaping from old fridges when their blown insulation was exposed when being scrapped.

 

[Mark]

I did see some comments in the FAQ page for one of these type of insulation boards about what to do if the insurers refuse to provide cover - they had a dedicated team to handle fire risk assessment. but that does imply that there are 'issues'.

http://www.kingspanpanels.com/uk/services/questions/index.htm

 

[Penners]

Hmmm - boiling point of 36.1C, flash point of -49C. This strange substance apparently combusts some 85 degrees colder than it boils! :?

That's not as strange as it sounds though, just think of petrol as an example. If you have a bucket of petrol at room temperature it doesn't boil, but it you light it (and please don't try this at home children!) it certainly burns.

Yes - it burns because the ignition source ( ie: your match or whatever) is raising its temperature to its flash point. It isn't igniting at room temperature.

 

[biffvernon]

I can imagine similar problems like there were with CFCs escaping from old fridges when their blown insulation was exposed when being scrapped.

Pentane has replaced CFCs in insulation because it is much less damaging. (Not that I'm keen on anything that can't be grown, like sheep's wool.)

 

[citizensmith]

CFS were scrapped as they were Ozone depleting, I'm not sure if they were also greenhouse gases. So we just swap one poor solution for another.

 

[Me!]

It isn't igniting at room temperature.

Yes I agree completely. I wasn't suggesting that it was ever going to spontaneously combust, just that based on the data quoted previously that there would be sufficient flammable vapour available at room temperature for it to be ignited by a spark from a switch, a candle flame or an open fire. I understand what Biff says about it possibly being safe by being contained in cells, but I'm not convinced I want to risk it. Are there any chemists or physicists out there who can explain why I have completely got the wrong idea, and that it is actually completely safe?

 

[biffvernon]

Try googling for PUR and PIR. There's loads of techie info out there.

 

[Rob]

Hello all.

Just thought I would feedback on a post I started over a year ago now, on the dreaded subject of multi layer foil insulation.

As you may remember, I have a c1700 cottage with a converted attic space, in which plasterboard had been screwed straight to the rafters, with no insulation. I was after a method of insulating the attic, without losing any headroom. I was unable to use any of the foam boards type insulation between the rafters are only 50mm thick, and would prevent the air flow.
I finally took the plunge and invested almost £1k on several rolls of the multi layer foil insulation from a well known DIT store. The foil was secured direct to the rafters, then a frame of 25mm batterning was added over the top, before all being covered in a layer of plasterboard.
This was all completed before the onset of winter, and I can honestly say that it has made a massive difference to the room. Before I was unable to use it as it was always too cold, and had the attic boarded off from the rest of the house as it make the first floor cold. This winter I was able to reinstate the access to the attic, the room remained at a reasonable temperature (considering there is no radiator up there yet), and during snowfalls the snow remained unmelted on our roof at least as long as any one else on the street. (whereas before it would bearly settle due to the heat loss).

If any one out there is considering using this type of material, I would like to make the following points;

Invest in a sharp pair of scissors and a staple gun - makes instalation amazingly simple and quick.
Wear a mask! The instructions dont mention it, but when you cut the material it releases tiny metal particles into the air.
I found it almost impossible to screw through, as the foam wraps around the drill bits and screws. you have to nail through it.
Ensure that you foil tape all the joints - this system relies on no air passing through.


In conclusion - I am extremely pleased with the ease of instalation and effecciency of the type of product. I appreciate that there are many other more proven methods available, but if you have limited head room, I would have no hesitation in recommending its use. Once I have installed my new staircase I will start the whole process again with the other attic room.

Kindest regards

Rob.

 

[Johneds]

If a substance has a temperature above absolute zero

So if we stay below absolute zero, say like in Newcastle, we're allright then?

You can't go below absolute zero as you "kana break the laws of physics, Jim" but absolute zero itself is fine (which is here by the way so Newcastle is above absolute zero)

Seems a bit late but only just spotted this. I was aware that you can't go below absolute zero. I was actually making a play on the fact that you said 'if a substance has a temperatue above absolute zero' - of course implying that you might get some substance below.

Anyway, you're wrong. I went to Newcastle in January about 10 years ago and it was below absolute zero.

 

[shelli]

Thanks for your replies.
I have started to look through the 148 pages of text on the greenbuilding forum with much interest. It appears that depending on how you test it, and under what conditions you can prove it either way!
What I am concerned with is less of the politics and physics, but the practicalities. Has anyone out there ever fitted this stuff to their own house? (ie they were around for a significant period after to judge the results).
On paper this looks to be the ideal solution to my problem, and I am confident I can fit it in the correct manner, so would really like some first hand opinions. Anyone?

Regards

Rob

We replaced our roof 12 months ago at near the beginning of our project - the lofts are liveable space ( a bedroom and a family playroom/hobby room ) - the insulation is Tri Iso super 10.

The rooms are warm and have been ever since the plasterboard went on.

We agonised over what type of insulation to use - fleece, rockwool, foil etc - but for us what it came down to was that we needed both insulation and not to lose head height (OH is 6'3" and doesnt want to develop a stoop)

as you ascend in the house you can feel the heat radiating - it works well for us because the lofts are open from the 1st floor (will post pics - promise) - the bedroom loft is accessed via an open staircase in a through room on 1st floor and the hobby loft is galleried and accessed from large landing via cast iron spiral staircase - so the trapped heat can return to 1st floor.

The hope is that when we finally light the 7kW woodburner in the downstairs inglenook fireplace at one end of house and the open fire in the lounge at the other - that all the heating will be taken care of and we never need the LPG tank again!!!

Shelli

 

[Horace]

Like many I read all the posts on the Green Building Forum and got a bit lost in the end. We re-roofed last summer and decided to add some insulation to an already converted attic space in a victorian house (the attic was orginally made habitable by the victorians but altered substantially by someone in the late seventies who didn't seem to worry about removing structural bits of timber). My builder and architect suggested multi foil. On the basis that it had to be better than what was there before (broadly nothing), and needing the headroom I agreed. It has worked extremely well. Hardly need any heating in our attic in winter and in the recent hot spell it seemed very effective in keeping the rooms at a reasonable temperature. Clearly I can't say what the alternatives would have done in the same situation but I am very happy with it. My sister lives in a converted chapel which was insulated with acres of kingspan and my attic seems cooler in summer and just as warm in winter. Pretty unscientific but that is my experience.

 

[biffvernon]

Good to see that some people are happy with what they've done and without wishing to rain on anyone's party I would suspect that much of the percieved thermal gain has been a result of the increased draghtproofing that is a side effect of Tri Iso 10. The Advertising Standards Authority has recently ruled that it does not do what it says on the packet. Details are posted on the Green Building forum.

If you really want good insulation in a limited space then consider aerogel in the form of Spacetherm from Proctors. Expensive but honest, afaik.