Wow, thanks everyone for the input.
I have to agree that the well built/insulated home is the first step. I'm in Virginia, so climate is moderate. I've looked at so many options my head is spinning. from straw bale, SIPS, conventional stick, panelized. am looking at metal right now, i like the 8" walls. now rat throws out ICF (sigh, thanks rat). so back to the heating system. i suppose my concern over offgassing is only part of the equation. i'm not all that concerned, of course i don't have asthma either /forums/images/graemlins/blush.gif. still, glue is used in so much anymore, like gluing the sub floor, most of the good glues have formaldahyde. i also am a bit concerned with the heating and cooling of the wood floor and the resulting cupping and warping it may cause. my understanding is the tubing runs at 125 to 130 degrees, the floor gets maybe 80? i've heard you cant use just any wood floor with radient. also, would seem better to use a floating floor, as oppossed to glue down or nail down. when i install air conditioning, i'll probably have a heat pump as well since it dosnt add much to the cost and heat pumps work pretty well where i'm at, would be an auxillary heat system. i do like the idea of being able to thwart the electric bills by throwing wood in an outside boiler or burning corn or bio diesel. so many choices, so little time. hope i dont die before i can decide.
paul