Unlike Michael, I am not amazed that your architect would spec single glazed divided lite windows. I have occasion to meet and discuss window and door performance with architects and builders and other folks in the industry and I am no longer surprised by anything I hear or see or read. There are many, probably most, architects who fully understand energy and basic building codes, there are others who don't fully understand them. Some of those want to learn the new codes and some of them seem of the opinion that the only idea that matters is their own "creativity" and be damned to anything that interferes with that. I am sure any of our GC friends who visit these sites have met that type all too often! Like Michael I agree that while some folks may prefer the aesthetic considerations of single pane windows, the energy performance - the pure waste of the indulgence - I believe is unconsionable. Has anyone bought gas in the past few days? That price is only going to go up in the future. All that of course does not affect a decision to buy all wood windows or clad windows. That is a personal choice and there are many options available both ways. There are some very nice replacement windows - all wood - that have excellent energy performance numbers. I also agree with corgilvr that in an older home windows are simply one avenue of energy waste. Money spent on improved insulation and weatherization is often a better investment than replacing windows...an energy audit will tell you what has to be improved. But, IF a person is replacing windows, then there is absolutely no reason at all forgoing with a window that has the energy performance considerations of the turn-of-the century rather than a window that will maximize energy performance in today's world - and keeping as close to the original aesthetics as is possible - a compromise between efficiency and looks. Good luck!

Good golly Miss Molly, I did not say that rest of the unit is immaterial. I only stated that the OA glass unit, and the the Low-e selected is a very big component of the overall effectivness of the the unit. Millworkman, you are absolutely right about the aspect of a poorly constructed window. As regards to adequate weatherstrip, I've got my opinions on that one too. Most window companies that manufacture easy-tilt windows use "finseal" weatherstripping. This is a "woolpile" with a thin film of plastic designed into the pile to stop air infiltration. Most window companies have two rows of the "woolpile" designed into the systems. Premium window companies have three rows of this weatherstripping. A lot of other systems rely on a jambliner with a foam backing to "press" the jambliner against the sashes. This system makes the window easier to install because the window can be slightly "out of square" and still perform adequately. The problem, for a consumer standpoint of these systems, is that the sashes are more difficult to tilt-in. The "Achilles heal" that many companies have is the sill tower. Many companies do not have "finseal" designed into the sill tower, which can cause massive air leakage. As far as whether or not 0.29 is a good U-value: hey, shop and compare. I'll say this, I've seen a lot of numbers out there and there is a lot of distortion out there. Numbers can be manipulated by the size of the unit tested. I've seen it, I've personally been to the testing labs and I know what some people are doing. A lot of the purchase decision is going to made by the reputation of the manuacturer as well as the reputation of the distributor. OK, now about materials: *Is wood a good insulator: yes. *Is vinyl a good insulator: yes. *Is fiberglass a good insulator: yes. *Is non-thermally broken windows good insulators: NO. *Is thermally broken aluminum windows good insulators: Somewhat Regarding the differences between the energy efficiency of wood vs vinyl, the differences are marginal. To millworkmans point, the quality of the manufacturing plays a big role into the overall efficency of any window.

We're in the process of building and just had our Marvin Ultimate casements installed. They are gorgeous. The Eagle quote we received was around $4000 less than the Marvin. If I recall correctly, most of the price difference was in the french doors (four pairs with sidelights, one pair without). The window prices were pretty comparable. What swayed us to the Marvins was the better exterior finish and the fact that the Marvin dealer in our area was VERY helpful. The Eagle dealer -- uh, not so much.

Good info here. I have been shopping Pella, Marvin, JenWeld, LLuminare and Softlite. The quotes are all over the place- or not coming in at all ?? This is what I need: new construction 46 windows, many "fixed" /picture windows, rest are casement, slider, horizontal slider, awning. Looking for contemporary/ modern look with black or dark aluminum exterior and black interior aluminum clad - frameless, mounted with a drywall wrap look and adding some ornamental sills later in specific rooms. Appreciate any advice for vendors in GEORGIA. ( house is in 30522 zipcode)