Fibreglass windows

[Anonymous]

I've only recently come across them. Anyone with any info or experience? They seem like an interesting option for hard to access spaces, as they should be able to last 20 years without needing any protection. They're being marketed as a seriously eco-friendly option. Mind you, what isn't these days?

[David Olivier]

Dan

My house is under construction and has them. Made in Canada – I wanted a U-value of about 0.8 W/m2K. I know nothing about any UK-made ones. The Canadian ones have been made for about 20 years, I think. They predated the Passive House standard and could achieve almost this U-value in 1992.

David.

[Mark Siddall]

Dan,
There is a UK company called Pultec that is manufacturing glass fibre windows. The BRE “Green Guide” study has given them an “A” rating (The highest standard).
The biggest problem with Pultec is that the system itself, whilst 'okay' (B.Regs), does not apprear to be of a good standard i.e. can't achieve silver standard (never mind Gold).
So whilst David's windows are based on what is in principle the same material technology, Pultec's do not achieve the same thermal performance. Whaen I looked at the glazing system this seemed to be due to the U-value of the frames not being what it could.

Mark

[Anonymous]

Thanks for that. Any contact details for the Canadian company David?

[Mark Siddall]

Dan,
FYI here's some background on the performance of the Pultec products (not that it will be your prime interest anymore): https://aecb.net/forum/index.php?topic=785.msg2923#msg2923

Mark

P.S. From other threads/discussions I note that David used Thermotech windows imported from Canada. (Also try refering to “Windows to meet the AECB standards” in the “Materials and Products” wing of the forum.)

[Mark Siddall]

Rod,
I, like you, was surprised at Pultec's performance. I had hoped for much more.
Fair point on the spacer I'll check and report back if I find anything (though I don't recall it being mentioned in the BRE report.)

Mark

[David Olivier]

Is anyone surprised I bought my windows from Thermotech?!

1. US/Canadian calculations are made with temps. of +21 degC inside, -18 degC outside and a 7 m/s wind blowing. Window and rooflight U-values are much worse. Also a realisitic-sized window, used to be 600 x 1200 mm casement.

2. EU calculations are made with temps. of +20 degC inside, 0 degC outside and I think a 4 m/s windspeed. European window U values are quoted at these conditions. Also with an unfeasibly large window for some projects, 1230 x 1480 mm.

Thermotech haven't yet done a calculation of U-value in case 2. It's likely to be similar to Passivhaus windows but their maximum window size is more limited. They had the U-value calculated by a BRFC assessor but I still don't think the assumptions were fully consistent with 2.

David.

[Mark Siddall]

Chris,
Pultec should know about this forum. I emailed them the web address and the link to the Silver/Gold standard windows specification/discussion. We can only wait and see if the penny drops. (When I spoke to them they said they impart from Canada.)

Mark

P.S. Scanned through the BRE report again. Strangely there is no mention of which spacer bar was used.

[Andy Mitchell]

I think maybe Pultec have widened their range then, since I last heard from them.

[Author]

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