Replies

1. 
   DanH | Oct 11, 2013 07:34am | #1

   Best advice is to worry more about the installer than the window.

1. 
   Norman | Oct 11, 2013 02:24pm | #2

   And...

   Also, buy a window by the construction quality, not just  the number of pieces of glass.

   Good luck.

2. 
   florida | Oct 11, 2013 09:27pm | #3

   First do the math and make sure the windows have a payback time you can live with. Down south the payback might be 75 years while in northern Canada it might be less than 10.

3. 
   Perry525 | Oct 12, 2013 07:36am | #4

   Triple or quad windows.

   You may find that having two sets of double windows does things better and cheaper. Having a four inch gap between the sheets of glass makes things a lot quieter.

1. 
   DanH | Oct 12, 2013 08:11am | #5

   Yeah, about 20 years ago I had a room in a hotel in Toronto.  It had a patio door of sorts that I didn't pay any attention to for the first 24 hours, then it decided to open it for some fresh air.  Was a bit surprised to find there were two doors, about 4 inches apart (which seemed quite odd at first).  But beyond that was an active rail yard on the other side of a tall fence, within a few hundred yards.  Had no hint it was there until I opened the first slider.

1. 
   Mike_Mahan | Oct 12, 2013 08:41am | #6

   I saw this arrangement once in Spain. If I recall the blinds were between the two doors. The doors would slide open from either side. I've never seen this kind of door in the US.

1. 
   DanH | Oct 12, 2013 09:36am | #7

   The arrangement does create the potential for unsightly but (mostly) harmless condensation on the outer window/door.  The simplest solution to that is to make the outer unit slightly leaky.

1. 
   Perry525 | Oct 13, 2013 07:07am | #8

   Triple or quad windows.

   Modern windows even quite cheap windows tend to have neoprene seals. As long as the inner windows are sealed in with low expansion foam to make them air and water vapor proof there shouldn't be any condensation on the room side of the outer windows.

   However, as you say allowing a small hole for the water vapor to escape by, the windows usually remain clear. But, then this rather defeats the idea of having quad windows to keep the home warm and the noise out. By the way, the four inch gap, or multiples of four inches is the way to keep noise out. If you have the space a 12 inch gap is as good as it gets.

2. 
   calvin | Oct 13, 2013 08:14am | #9

   is as good as it gets.

   Not quite-

   Tip one of those window pairs out of plane with the other (vertically) and you get even more-old sound studio technique.

   Otherwise you have a drum effect-even if lessened (deepened in tone) with the thickness of separation.

   no bull shit.

3. 
   DanH | Oct 13, 2013 09:14am | #10

   The small hole need not be large at all, and will not cause a major drop in temperature between the two windows -- it's just necessary to assure that the outer window is not quite as airtight as the inner one.  The problem is the old, dreaded "double vapor barrier" effect, only in this case it's a real problem.

   But this discussion is largely academic.  In most cases of operable windows the double window scheme is impractical -- it's not economical, you can't use casement or awning windows, the thickness builds up to much, etc.

   Which gets me back to my original point:  It only takes a slightly bad installation (not completely foaming the gaps, etc) to negate any benefits of a triple pane window.  One is probably better off investing the money in assuring that good-quality double-pane units are installed correctly.

4. 
   Clewless1 | Oct 15, 2013 09:28am | #11

   You might consider Heat Mirror (tm) glass vs. triple pane. I've always been a big fan of this product ... although its availability might be iffy. Over the years it has had some issues w/ availability.

   It's lighter weight, lower bulk than triple pane and usually much better U-value.

   It came out in the early 80s. It's a little like cassettes vs. 8 track ... superior technology in spite of higher popularity of 8 tracks.

   You can get it in any of the standard configurations as normal insulated glass ... e.g. tinted, mirrored, etc. You can even get e.g. double Heat Mirror.

   Heat Mirror is the 'original' low-E glass technology, I think.

   Price may be affected by availability. When I first purchased some in the 80s it was relatively reasonable. But when I had to replace a broken unit ... yikes! Your locality may be key to price as there's only a handful of assemblers of this product (it requires a special machine).

   It's not for everyone, but if your considering the extra expense of triple glass, consider it as a good alternative and superior thermal performance.

   Google "Heat Mirror" and check it out if you like.