Hey, slug, from your quick comment on insulation plans it sounds like your first line of research ought to be in the area of building science and superinsulation methods. For new construction in a Zone 6 climate it always makes sense to put the first money into a very well insulated shell. A simple flash & batt applied to conventional framing certainly isn't anything anywhere near superinsulation. Looking for a cheap source of energy to keep up with a heat sieve of a house isn't the way to go. It doesn't cost all that much more to do a really good job on the shell. Do that and then see what heating system makes sense. The heat load will be far lower, the house will be far more comfortable, and GSHP becomes a much better match for it.

Good advice. As I mentioned before, size of the house makes geo pay back questionable. I think you may want to compare envelope improvements, and other heat plants against geo.
J

I concur with the last two posts

The cheapest energy is that not consumed. Manage demand before investing in supply.