Community: Energy efficiency and durability

I previously had asked about the potential of constructing a rudimentary geothermal basement by purposefully NOT insulating the masonry walls of a basement. Martin pointed out that the ground temps in NY/NJ/CT in winter at the surface are freezing and not until something like 48 inches are they above freezing, say around 40 to 45 degrees? Thus making it clear the walls should be insulated. But what about the the floor slab? Assuming a depth of say 9 feet at the slab's underside, would this not be a constant 55 degrees or so? Thus be warming in winter and cooling in summer?

I am an architect in Atlanta, GA (climate zone 3) mostly designing modern/contemporary homes that typically have flat roofs. There seems to be a lot of conflicting information and opinions out there as to the best way to insulate these types of roofs. Typical construction would be 12" deep ceiling/roof I-joists or 2x4 open-web trusses with flat OSB decking above. The most common potential options (all unvented scenarios)are:

I am building an Energy Star certified home with fiberglass, triple glazed, low e casement windows and slider/patio doors in Connecticut. I prefer using a Canadian company because of their expertise with fiberglass, triple glazed windows and sliders. I must have window specifications for the Energy Star certification, preferably NFRC ratings or at least independent U, SHGC and VT value ratings. Window ratings do not seem to be diificult to acquire but slider/patio door ratings can not be provided by some manufactures for fiberglass triple glazed sliders and French doors.

Does anyone have experience with Serious Windows or Canadian fiberglass windows? I'm having a difficult time finding high SHGC windows (with a U-value less than or equal to 0.30) for my passive solar home that are affordable. Looks like the fiberglass windows can give me the performance I'm looking for, but I can't find any local installations to inspect the quality of manufacture.