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Aerogel

Archer

By Archer
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Archer Regular Member

Archer

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Hi All, 

 

Embarking on a home retrofit and considering options. Our house is 1970s timber frame with 75mm mineral wool insulation in the (90mm) studs. We might be able to fit external wall insulation to the 1st floor which is cedar shingles  but the ground floor has brick cladding and a cavity...

 

So... Looking at options for IWI, will probably do it room by room rather than a big bang and I like the idea of Aerogel because it wouldn't need a huge amount of extra space to make a big improvement. The cost though is hideous. 

 

This is a long shot, but wondering whether anyone here managed to find an importer from China or elsewhere that makes this product more affordable? 

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RobLe Regular Member

RobLe

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What’s the lambda for the aerogel ?  I don’t think the blanket stuff typically used is as magic as the solid spaceage (silly price) stuff !  And compare it with regular PUR, which I have seen as low as 0.018, though it’s mostly 0.022W/K/m.  Consider VIP (vacuum insulation panels) perhaps?  I think these are better, but tricky to use as they come in discrete sizes.  I’m not sure why they’ve not taken off.  Digikey have some, I think they get used in high end fridge freezers (ours has them).  Eg this one for 1off cost £51, 600x600mm, 25mm thick, U=0.18W/m/degC.  You’d need 100mm or a bit more of PUR to get that.  Nb, I had to convert imperial R to metric U values, I think I got it right, pls check!  I’ve not used the stuff mind.

 

https://www.digikey.co.uk/en/products/detail/panasonic-industrial-devices-fbd/CNRZZB78400/9558502

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Temp Advanced Member

Temp

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4 hours ago, Archer said:

I like the idea of Aerogel because it wouldn't need a huge amount of extra space to make a big improvement. The cost though is hideous. 

 

Raw aerogel is good stuff but I don't think it's available and too fragile? The blanket version doesn't appear to be much better than rigid PIR...

 

Google found..

 

https://thermtest.com/application/aerogel-thermal-conductivity-hfm

Quote

 

The aerogel blanket displayed a thermal conductivity reading of 0.024 W/mK at 20˚C.

 

 

 

 

https://en.m.wikipedia.org/wiki/Polyisocyanurate#:~:text=PIR is typically produced as,on the perimeter%3Aarea ratio

Quote

PIR is typically produced as a foam and used as rigid thermal insulation. Its thermal conductivity has a typical value of 0.023 W/(m·K) 

 

So in this case its marginally worse not better.

 

Note: Thermal conductivity is the a property of the material. Its like the U-value for a 1m thick block of the stuff. So to calculate a rough U value for any thickness T (in mm) you can multiply by 1000/T. 

 

So U value of 100mm thick would be 0.023 * 1000/100 = 0.23 W/m²K. That's the insulation alone not a whole wall.

 

 

 

 

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Archer Regular Member

Archer

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4 hours ago, SteamyTea said:

Our @DamonHD is the man to chat to. He did similar in his place.

improving airtightness in a 70s place will make a huge difference.

Cheers, hoping Damon responds with some words of wisdom. On airtightness, yes I heard that for detached houses (ie. with a relatively poor form factor) that airtightness starts to become more significant than insulation. It also feels like it will be harder to sort out though. We've got what looks like a pretty well installed and maintained polythene VCL between the plasterboard and the studs. The loft is well insulated but very drafty so planning to tackle that as as relatively easy win. Other than that though I worry that airtightness might be difficult to drastically improve. Ideas welcome though

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Archer Regular Member

Archer

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51 minutes ago, Temp said:

 

Raw aerogel is good stuff but I don't think it's available and too fragile? The blanket version doesn't appear to be much better than rigid PIR...

Proctor list the Lambda value for Spacetherm as 0.015 W/m2 so considerably better than PIR but you're right, it's actually not as good as I thought. The literature online seems to suggest that you can use about half the thickness of Aerogel for the same insulating performance in PIR - that value suggests that it's somewhat worse than that - and costs around £250/m2 (for c.15mm)

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Archer Regular Member

Archer

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4 hours ago, RobLe said:

Consider VIP (vacuum insulation panels) perhaps?  I think these are better, but tricky to use as they come in discrete sizes.  

 

I know absolutely nothing about VIP's but my instinct is that they would be incredibly hard to DIY install and probably not suitable in walls where they could be accidentally punctured over time?

 

PUR board with a conductivity as low as 0.018 sounds very interesting though, do you know who supplies this?

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DamonHD Regular Member

DamonHD

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11 hours ago, Archer said:

Cheers, hoping Damon responds with some words of wisdom. On airtightness, yes I heard that for detached houses (ie. with a relatively poor form factor) that airtightness starts to become more significant than insulation. It also feels like it will be harder to sort out though. We've got what looks like a pretty well installed and maintained polythene VCL between the plasterboard and the studs. The loft is well insulated but very drafty so planning to tackle that as as relatively easy win. Other than that though I worry that airtightness might be difficult to drastically improve. Ideas welcome though

Hi,

 

Not sure that I have any of that wisdom stuff to dispense, and I am in the middle of preparing for a meeting, but here is some of my write-up which may be useful (follow the "See also" links in the sidebar):

 

https://www.earth.org.uk/note-on-Spacetherm-aerogel-thermal-insulation.html

 

Rgds

Damon

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Archer Regular Member

Archer

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This is really useful thanks @DamonHD. It's always worth asking a question on Buildhub. Awesome forum... The rabbit hole that I'm now exploring is whether spending money on PV to offset increased energy use will actually be more cost efficient than significant extra insulation. I'm sure others have been on this journey, will share any interesting findings. 

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