Re: "Doc Holiday's" suggestion of floor instead of attic ducting.

OK Doc, What you've said is certainly true. (Attics are typically very hot in summers, making attic duct branches and the equipment subject to increased losses for cooling.) The attics here are virtually unbearable in the summers, even with lots of insulation, pro design, and maybe forced attic ventilation. So why are ducts and Eq. put in the attics when A/C is essential for many 100+ days?

Because ducts CAN'T go in the crawl space or basement, since most houses, even the $upscale ones, are build on a slab on the ground! Thus the lossy attic location.

HOWEVER, our "Dream House" (not quite a nightmare yet, but may be if it doesn't stop raining which has made all construction around here halt) is an "upside down house" configuration. That is, the main floor (which has all of the essential rooms on it) is at street level, but the "2nd" floor is underneath it, for now as an unfinished basement. And it's way cool there. So, using "under" (the floor) ductwork sure makes sense.
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Keep up the good suggestions guys. This house project will have several innovations ("experiments?") built in, like fancy lighting controls etc. Perfect for a frustrated retiree to tinker with. I'll gladly let y'all know how things work out.
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ps to Jacob: System Efficiency is obviously a "desirement," but comfort (cold feet) is the primary thrust here. Interestingly, the power bills in this all-electric community don't seem that bad, maybe $200-300 during solstices, so energy-saving gymnastics aren't worth it if they cost much.
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ps to The Doc: Unfortunately we don't have money to burn, but sometimes it seems it gets burned anyway!

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Thanks to all, Keith