[Greenbuilding] R-20 windows (was Re: Glass overhead doors for passive solar application?)

[Rob Tom]

On Tue, 05 Dec 2006 10:07:48 -0500, Keith Winston  
<keith at earthsunenergy.com> wrote:

>>> If you find an R-17 window, I'll use it in every single
>>> project from now on, I promise you!

> Rob Tom wrote:
>> Thermotech, just for the fun of it, made a window that outperformed an  
>> R-20 stud
>> wall.

> Nope. I've had long conversations with Thermotech. The best glass they
> have available is the Superglass I spoke of.


Keith;

I'm guessing that you didn't ask about the R-20 window specifically in  
your "long conversations".

I just Googled "Thermotech R-20 window" and the first hit was:

http://homeenergy.org/archive/hem.dis.anl.gov/eehem/95/951113.html

[quoting from the above page]

	Thermotech Windows Ltd. recently unveiled a prototype window unit with
	an R-20 insulating glass panel. The window's five layers of glass have
	multiple "soft" low-e coatings and are separated by Edgetech's  
SuperSpacer,
	a silicon foam spacer with a high insulating value. Xenon gas fills are
	used to provide maximum thermal resistance. The frame, from Accurate  
Dorwin,
	has one of the widest glazing cavities available, and is made from foam-
	filled pultruded fiberglass. This frame, when combined with triple glazing
	and insulating spacers, forms the most energy-efficient window ever made.
	Thermotech's R-20 window is not currently in production, and no cost  
estimates
	are available; the company simply wanted to prove that it could be done.
	Solplan Review, May 1995.

[end quote]


May 1995. Man! That was like, a lifetime ago in terms of window technology.

Although the R-20 window was a just-for-the-heck-of-it prototype, given  
that you've *promised* to buy for life, any R-17 (or better) window, I'm  
sure that Stephen and the boys at Thermotech could be coerced into making  
some more up just for you.

So you didn't like the price for the plain old Superglass window, eh ?

Then I guess you're going to be even less happy with the cost for  
custom-made R-20 glass, but a promise *is* a promise, no matter what the  
cost. Right ?

===* ===
Rob Tom
Kanata, Ontario, Canada
<archilogic at chaffyahoo dot ca>
winnow the chaff from my edress in your reply