I will be building a new home and would like some advice for the type of window glass to get. I will be using the Monarch window for all double hung vent and picture windows, and Kolbe for inswing casement. I chose Monarch because their window seemed to be the easiest to open (aside from the smooth as butter pulley action that Kolbe and Marvin makes, but at about $2K per window was totally out of the budget), and Kolbe because they seem to be the only manufacturer of *inswing* French casements (even though I had some serious issues with the staff at Kolbe and would prefer to take my business elsewhere.) Presumably I will be getting doors that also use Cardinal glass.

Anyway, both use Cardinal glass, and can use any of the double glazed glass, such as the 240, 270, 272, and 366 (am I missing any?) So it is question of which of the glass to use for the different applications. I am in the hot and humid Gulf Coast, at about 30 deg latitude and just barely in the South region (the South Central region is very close.) If it makes any difference, I tend to be away for about half the winter skiing, so the winter HVAC is even less important.

The general design of the home is a long skinny, "Country" style being long exactly on the east-west axis. The south side has a 2' eave (at 8' height), and the windows in general go down to about 32" high (meaning that they will receive very little sun during the summer side of the equinoxes.) The porch is an indentation under the same main module of the home, and is set back about 9' from the end of the eave, so the window and door there will never receive any sun, even during the winter solstice . The east side has some windows, but the west side will have none. The north side has a few windows, including 2 large picture windows. There are also a few inswing windows at northeast or northwest (exactly 45 deg orientation.) A grand piano will be very close to one of the north side picture windows (which obviously should not go through quick temperature changes.) All the windows except the picture windows and doors will have screens.

The south windows will start to get some "bad" sun in the late summer through the early autumn (which is still big time cooling season), but the wide eave makes it possible that such "bad" solar gain could be offset by the "good" sun during the winter, or at least that solar gain is not such a big deal; there is one south window close to the west end such that there is a problem with the sun coming in from the west rather than the south (this could be considered to be like a west window.) The east windows will be brutally attacked by the sun, and nothing short of bermuda screens can do anything about it. The north windows will barely have any solar gain even at the summer solstice (although the picture window by the piano is still a concern even with a little sun.) I consider the obliquely oriented north windows as almost equivalent to being east or west.

So the criteria for the selection is first and foremost low U value, with high VT (except for one of the oblique inswing windows just west of the piano that I want to be as dark as possible) - especially for the picture windows, and not so important for the screened windows - and low SHGC for the east or west windows, possibly low SHGC for the south, and of little relevance for the north, and porch.

It seems that any window for which low SHGC more important than high VT, the 366 should be used. When high VT is most important, or SHGC is irrelevant, the 270 (or 272?) should be used. When darkness is most important, the 240 should be used. Actually the 366 seems to be a win-win window all around as its U & SHGC is almost as good as the 240, and its VT almost as good as the 270. (The 366 must be very expensive, or everyone would be using it?)

So in my case I will be using:

240 - the dark window (will also be tinted)

366 - all east or west windows (except the dark one), including the south window close to the west side

270 (or 272?) - the north and south porch windows

366 or 270 (or 272?) - the remaining south windows

So what do you all think about this? Any ideas on what I should do about these remaining south windows? Any idea on the relative cost of Cardinal 270 vs. 366?