Almost afraid to ask how much they will cost. And looks like you will need to frame your house with 2X6 studs.
http://www.ebuild.com/articles/articleId.840125.hwx
Would like to see these come on the market too.
http://www.bine.info/pdf/publikation/projekt0108englinternetx.pdf
The team offers expert advice on building an affordable new home that follows building-science best practices.
"I have learned so much thanks to the searchable articles on the FHB website. I can confidently say that I expect to be a life-long subscriber." - M.K.
Replies
I'd be happy with R-6 which is about twice the average Marvin/ Andersen/ Pella. It's time to contact them and demand better performance.
Send them an email right now.
http://www.marvin.com/?page=Contact_us
http://web.pella.com/supportcenter/Pages/ContactUs.aspx
http://www.andersenwindows.com/servlet/Satellite/AW/Page/awForm_ContactUs/1104867941444
Thanks for the info. I've got 6 or 7 upstairs windows in my future. Well that and insulation & new HVAC. sigh
70F. Deeeeeelicioussssss.
Isnt Heat Mirror a Hurd product? I would love R-20 windows. You loose most of your heat through thoes.
Window technology hasent really evoloved that much.
No, Hurd has used the Heat Mirror product for a long time ... good for Hurd for sticking to it!!
It's not only the cost that's worth finding out. But also the visible light transmittance and solar heat gain coefficient. I'd be willing to bet that they're both very low. Not much better than a wall ;-)
The vacuum technology is an interesting retro-revival. The original Anderson IG units were welded glass (no edge seals) with vacuum. The only reason they didn't perform better is the conductivity of the glass edges.
This new vacuum window performs at R-11 and has as high a SHG as a lowE triple. And it's thinner and lighter. That looks much more promising to me than the triple heat mirror monstrosity.
Solar & Super-Insulated Healthy Homes
Edited 1/8/2009 8:50 pm ET by Riversong
Standard Heat Mirror 88 - had a shading coeficient of somewhere around 0.70, I believe (that was before they switched to SHGC). Not sure about the visible light ... but I think that was very high ... as Heat Mirror is a clear glass, not unlike 'standard' Low-e glass. The mylar film is invisible to the eye ... you can see it only by finding the small pressure compensation hole near the corner of the glazed unit. ... or by looking at a reflection ... which is 3 instead of 2 with standard insulated units.
Standard Heat Mirror 88 - had a shading coeficient of somewhere around 0.70, I believe (that was before they switched to SHGC). Not sure about the visible light ... but I think that was very high ... as Heat Mirror is a clear glass, not unlike 'standard' Low-e glass.
To convert SC to SHCG, simply multiply by 0.87 (the SHGC of clear glass).
Heat mirror is not glass, but a polyester film. It can be placed between either clear or coated glass.
But Heat Mirror TC88 with clear double glazing has a VT of 0.65 and SHGC of 0.5.
With one lowE pane, the VT is 0.56 and SHGC is 0.33.
These are center of glass, not whole window, numbers.
Riversong HouseWright
Design * * Build * * Renovate * * ConsultSolar & Super-Insulated Healthy Homes
Edited 1/11/2009 8:58 pm ET by Riversong
I think the film is mylar, not polyester.
I'd be surprised if standard clear low-e glass had a SHGC as low as 0.33. I think it is typically up around 0.60-0.70 if I recall right.
I think the film is mylar, not polyester.
http://www.southwall.com/southwall/Home/Company/History.html
"Heat Mirror is a clear, polyester film with a 3-layer coating that transmits light, but reflects long-wave infrared energy."
I'd be surprised if standard clear low-e glass had a SHGC as low as 0.33. I think it is typically up around 0.60-0.70 if I recall right.
The numbers I posted are from the Southwall website.
Riversong HouseWright
Design * * Build * * Renovate * * ConsultSolar & Super-Insulated Healthy Homes
I guess I stand corrected. Maybe they used to use mylar. And I was weened on shading coeficient, so I'm not used to the SHGC values. Good information, for sure.
Mylar is polyester:
http://heritage.dupont.com/touchpoints/tp_1952/overview.shtml
Mylar is the trade name.
Billy
It is Mylar not mylar."Mylar¯ is an extraordinarily strong polyester film that grew out of the development of Dacron¯ in the early 1950s. "From Dupont website..
William the Geezer, the sequel to Billy the Kid - Shoe
"Mylar¯ is an extraordinarily strong polyester film that grew out of the development of Dacron¯ in the early 1950s. "
Why would they want to admit that? Dacron polyester was that awful shiny-bottom pants material popular in the 50s.
Riversong HouseWright
Design * * Build * * Renovate * * ConsultSolar & Super-Insulated Healthy Homes
Edited 1/12/2009 4:43 pm ET by Riversong
It also makes great sails..
William the Geezer, the sequel to Billy the Kid - Shoe
also makes great sails
Well, given my druthers, I prefer spectra or kevlar thread to mylar for hard-worked sails. Dacron always seemed to stow & deploy better for me.Occupational hazard of my occupation not being around (sorry Bubba)
You got that right ... I fly w/ mine!!
Heat Mirror technology has been around for a long time. It was originally developed by some MIT folks back in the 70's (as I recall, so don't quote me).
It isn't really very popular with window manufacturers because it has had a history of problems related to seal failure and other problems with the suspended film (wrinkles, for example). It does perform very well, but a lot of people arer afraid of it. And it tends to be expensive.
Hurd does offer Heat Mirror in some of their windows, but it is an upgrade.
Actually, glass technology has come a long way in recent years. Although it may not seem like it when looking at the improvements in window performance, the difference between a less-than R1 single pane versus an R6 triple is an amzing technological leap. (And as an aside, the window companies mentioned do have windows that have overall R values between 4 and 6 depending on company - they just aren't really advertising them heavily).
Vacuum technology for IG units isn't really new (however, the welded glass IG's of old were not vacuum inside - even though folks often would refer to them as such). What is "new" is the ability to hold a vacuum for any appreciable length of time and using "buttons" that are not readily visible - or are aesthetically pleasing to the homeowner - to keep the glass from collapsing inward.
Glass is flexible. In the real world, even changes in daily barometric pressure results in the glass in an IG unit going concave to convex (or visa versa) because of differences in pressure inside the IG versus outside the IG. It isn't possible for glass to maintain flatness if the airspace in the IG has even a partial vacuum without use of something to physically hold the panes apart. Thus the "improvement" in the "buttons" in the vacuum IG - and potentially in the seal to keep air from entering the "vacuum" space.
All of which doesn't mean that it isn't a good idea...
The failure problems is not much unlike standard insulated glass ... properly installed, it should be good. The commercial installation I've seen, to my knowledge never had problems with it. I worked in the building after it had been in about 10 years and there was never a problem.
As for wrinkles ... that problem tends to be 1) rare and 2) generally minor. I think I've seen a wrinkle ... and if I recall, visually it was minor.
Relatively very few manufacturers use heat mirror because of the problems associated with it in the past. Window companies are afraid to use it because they don't trust the reliability of the product.
This perception may not be fair or even accurate anymore, but it is real and past problems have limited the use of this product in the industry.
Despite the very good energy performance numbers associated with Heat Mirror, the huge majority of window companies are looking to triple pane glass with multiple LowE coatings to improve performance rather than investigating the Heat Mirror option.
Again, the perception of heat mirror as an unreliable product might be totally wrong, but it is pervasive in the window industry.
Right. That is unfortunate. I think part of the reliability problem has to do with where the unit is made vs. where it is shipped. I think there is still an issue with elevation an pressure affecting the seal longevity ... although I'm not well versed with this issue.
I would think Heat mirror to be as reliable as e.g. triple glazed. They both have an edge spacer that is not continuous through the width. But properly made AND installed, the Heat Mirror should provide comparable quality/dependability.
I think that window manufacturers know and understand and accept the risks of bonding spacers to glass, be it two lites or three lites, but they have no real history on bonding spacer to film to compare with - again, other than the historical perception that bonding to the film is inferior to bonding to glass - be it currently accurate or not.
as always, thanks for bringing serious and practical information to a window discussion here.
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
Thank you
robert.... do you have an update on that electric resistance window development ?
I've used Heat Mirror glass since the early 80's. I've analyzed, recommended, and used it in many applications. I put about 400 sqft in my own house at one time. The city hall where I lived used it ... it was one of the first to apply it ... several thousand sqft in a classic 7 story art deco building.
I've also seen it used in a building built around 1995 ... about 150,000 sqft floor area of office building ... speculative leased space with LOTS of glass.
I had to replace some of it on my house when a rock got thrown through it. Then I began to learn of the current issues ... which tend to center around availability. Manufacture of the glazing units is a special process. In the early 90s ... there were like only 4 places out west that did it (one was in Seattle, one in Spokane, WA). Not sure the current status of manufacturers. That will be a key in obtaining it.
Technically, I'm a BIG fan of Heat Mirror ... you can adjust the low-e coating to your needs (i.e. heating or cooling). You can still tint or mirror finish if you want (which I've done and seen done). You can use a single mylar film (most economical) at around U-value 0.23 or like your link ... do multiple films to really get your U-value down.
Benefits: Noise, energy, comfort. Heat Mirror significantly reduces the cold wall affect - that is the cold you feel as you stand in a room w/ lots of glass on a cold day. This is great especially if you happen to have a large expanse of glass. So rather than turning up the stat to compensate for this cold wall affect, you can leave it alone.
Heat Mirror IMO is a very good product that is undersold. If you can find a source at a reasonable cost ... I'd highly recommend it. BTW ... many/most glass shops will have no idea what you are wanting if you ask for it. You will need to explain it to them and have them check the availability through their sources. Most think it's simply mirror finished glass.
"The city hall where I lived used it"
You lived at city hall?Was this during your rebellious years?
Jon Blakemore RappahannockINC.com Fredericksburg, VA
The city hall in the city I lived in ...
Too bad, the alternative sounded so much more exciting.
Jon Blakemore RappahannockINC.com Fredericksburg, VA
This thread reminds me of SAGE glass. I was going to get some SAGE glass in my Velux skylights -- until I found out the price, which was about ten times that of the standard skylights theselves.
man, did those links ever have a bunch of addvert pop ups and re-directs, never even got to readn anything on the main topic.
Try this site ... it's the Southwall home page ... they have the rights to Heat Mirror ... I guess they make the film for distribution to assembly locations.
http://www.southwall.com/southwall/Home.html