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Green Building Bible, Fourth Edition
Green Building Bible, fourth edition (both books)
These two books are the perfect starting place to help you get to grips with one of the most vitally important aspects of our society - our homes and living environment.

PLEASE NOTE: A download link for Volume 1 will be sent to you by email and Volume 2 will be sent to you by post as a book.

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  1.  
    Happy New Year, all!

    It appears that the most recent thread about VIPs on this forum was in 2015. Has anyone experimented with VIPs since then? With their R-value 5x higher than the nearest alternative (not counting aerogel, of course) is quite impressive. So I was thinking how to address the issue with the 10x higher cost.

    Cost: for a tiny house, VIPs sound particularly attractive. E.g. for a 3x6m footprint and 2.5 (h), one could use VIPs just for the walls, and use regular polyurethane for the ceiling and the floor. With the walls only, we need less than 50 m2, if my estimate is correct. The total cost is thus <5000 EUR assuming 100 EUR per m2. Can one obtain VIPs as surplus from a refrigerator company?

    Scavenging: I work in biotech, and we occasionally get shipping of enzymes encased in VIPs. The packaging is typically discarded.

    Decay: This Korean paper measured the conductivity and the inner pressure for fumed silica VIPs under accelerated ageing conditions. Although they pointed out that the manufacturers' specs on the R values and the internal pressure could be off by up to 25% and 2-3 fold (respectively), the deterioration was consistent with a lifetime of 25 years:

    https://www.sciencedirect.com/science/article/pii/S2214509517301109?via%3Dihub

    The full pdf is available via sci-hub dot tw

    DIY: Since one does not need much for a tiny house anyway, how crazy would DIY be for VIPs? The skill set appears similar to making DIY composite panels. One needs aerosil 200, vacuum down to 50 mbar (my pump can do this), a heavy duty polypro sleeve (a roll of 100 m, 1 m wide is £100, I have one), and a bag sealer. Don't know for how long the vacuum would hold though. Make valve on each panel for re-pumping as needed? :) Aerosil 200 is available from Easy Composites for about 20 quid for a 10-liter bag. If my math is correct, one 1 m x 1 m x 25 mm panel would need 4 bags of aerosil.

    Finally, they've been exploring alternative to aerosil, which seems to account for up to 70% of the cost of VIPs. Here is a 2017 academic paper (I was not impressed with the results, actually).

    https://www.sciencedirect.com/science/article/abs/pii/S0870831217300435

    The full pdf is available via sci-hub dot tw
    • CommentAuthorTimSmall
    • CommentTimeJan 3rd 2019
     
    Sounds fun but also a lot of setup and development work for a small project, and if it fails, it "fails hard". 25 year life span sounds a bit too short I think?
  2.  
    >>25 year life span sounds a bit too short I think?

    sounds OK for my remaining lifespan :) 25 years corresponded to a 90% percentile, I believe, but I may be wrong. I.e. not a half-life, or 1/e decay.

    I tend to build things in a reversible way, for easy maintenance (it's a tiny house project).

    Well, I got 250 g of Aerosil 200 from Easy Composites. which, in terms of space, fills a 5L (!) jar.Whatever I find, even on a small scale, will be useful in the lab as well. Then someone else can use the knowledge, if they want to.
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