Friday, May 25, 2012

ETFE offer from Holscot!

24 May 2012: I wrote a while back about the virtues of ETFE, immensely strong and durable transparent plastic sheet. I was lucky enough to meet Holscot, the leader in the East Midlands of fabricating ETFE into frames and other structures - based in Lincolnshire. Holscot had demonstration aluminium frames with stretched and inflated sheets of ETFE.
    The product is strong enough to resist wind loads and thrown stones, and has durability so long that its ultimate life is not known - all ETFE in use since it was first introduced 30 years ago for 'glass'-houses is still in excellent condition.
   I immediately recognised that this would be the ultimate material for a sunbox. Although more expensive than polycarbonate and glass, it is cheaper than the cost of forming a glazed box with glass, but has much higher transmission. It can be double glazed, to provide insulation. More normally, it is inflated gently (like a cushion), but if thermally stretched over a frame, it will shrink tight and remain taut enough to resist domestic scale wind loads. Holscot have a Patent on the process of doing it without needing inflation.
   Examples of the use of ETFE are the Eden Centre in Cornwall, the Space Centre in Leicester, the Beijing Aquadrome, Beijing National Stadium, The Engineering Student Centre roof in my own university, the Allianz arena (where Chelsea beat Bayern Munchen last weekend, and too many more to mention. (Illustrations from Wikipedia)

This would provide the ultimate level of transparency to solar energy that I could possibly have for the Sunbox. Holscot have written to say that they are willing to provide sponsorship for the Peveril Solar project (in the form of ETFE!), recognising that this unique application of ETFE can be another proof of the benefit of using it.

   The ETFE is so transparent to energy capture that it would nearly equivalent to leaving the black collectors naked to the sun on sunny days. With the double glazing option, the low heat loss would ensure that the sunbox would continue to work in winter and night conditions. So if ever I am to make other sunboxes for ground source heat pump users, this could prove to provide the performance that justifies the investment in a sunbox and even in a GSHP in the first place. With the experience gained on the first one, it is clear that the use of ETFE for the front hinging up panel would be a clean and one-piece solution, virtually interchangeable with the triple skin polycarbonate that I used previously (and which I suspect of having sun filtering properties.)
As I shall have to have scaffolding anyway for the proposed house extension, it's going to be all part of the summer operation to make this change.

1 comment:

  1. It was clear that the by using ETFE the front hinging up panel would be a clean and one-piece solution.

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