.

I'll toss out a few thoughts . . .

Radiant in-floor heat is GREAT ... and can be accomplished with geothermal systems. It likes a temp of about 120 deg F for the water; shouldn't go any higher. You CAN'T do A/C without ductwork of some kind; to my knowledge. Run cool water through radiant heat system and you'll get slightly cool floors with moisture condensing on them . . . .

No matter your type of heat, or it's source ( fuel ), I would not consider building a place WITHOUT an ERV ( Energy Recovery Ventilator ). Any place built today should be very tight . . and that by itself means you MUST have air exchange from outdoors . . an ERV simply functions like an open window in terms of allowing fresh air in; but extracts heat from the outgoing air to pre-warm the incoming air. It also recovers the "cool" from outgoing air during A/C season . . and will swap humidity as well. The difference between an ERV and an HRV ( Heat Recovery Ventilator ) is that HRV's do heat ONLY; ERV's can swap humidity as well. I'm no A/C fan; while they've come up with "replacements" for CFC's; they're only a small step away in terms of environmental impact. Naming them things like "Puron" with a cute little globe symbol does not make them less harmful. Consider that proper overhangs, free cooling from trees, and perhaps a dehumidifier can make a place fairly comfy without a lot of equipment to run / maintain. Good insulation is a given.

I'll also suggest cellulose insulation ... . loose / blown are simply better insulation; and certainly FAR more environmentally friendly from any angle. The stuff WON'T burn; I took a torch to a sample from the bin before they blew my attic full . .. couldn't even get it to smolder. Did same to a 20 + year old sample from a friends house; same results. The borate salts used to treat cellulose to make it fire retardant also give it great anti-vermin qualities . . . and yet it's quite safe stuff compared to other things used to kill bugs, ants, termites etc. . .

Consider metal roofing.... not necessarily "standing seam" type; as that can be very expensive. There are profiled types which are far less costly; and can truly make a dramatic impact on the looks of a place. If you've got lots of snow; consider also that metal roofs shed snow like crazy .. no more shoveling / ice dams etc. It also cools off MUCH faster at night . . . . instead of a huge, hot mass of traditional roofing material. Also; at least here you can simply lay the roofing on a grid of 2 x 4's; skipping the sheathing completely. THAT adds up to a few bucks for sure. It also makes a darn nice muffled sound during a rain . . . and it'll likely outlast YOU . . . no replacing the roof every 10 - 15 years at great expense / mess and filling up the landfill . . . . .

Sounds like you're early in the process ... study / look into things carefully . .. get LOTS of opinions; especially from those who actually HAVE what you're asking about. . . not just that they've read this or that . . . you can't plan too much or too far ahead . ...

Good luck . . .

Bob

SIPs, SIPs, SIPs. Structural Insulated Panels are the WAY to go. There's a couple posts here on this forum, and others on the Building a Home forum. And there are some good people in Southern Michigan/Northern Indiana installing them.

Check your library for information about building a new home.

Check your local group (volunteer agency directory?) that knows about volunteer groups, community groups and other local groups - no doubt there's one that's been checking out the various issues that relate to home building.

Be somewhat sceptical of the average builder, for many want to build the "same old ... same old". There are some new materials that may be less costly, are more environmentally friendly in terms of raw materials, and in terms of maintenance, as well - including heating.

You're embarking on a great adventure.

If you get a home that suits you to a "T" and uses some worthwhile and environmentally friendly materials, which prove to be durable and require little maintenance, including heating (and if you live in southern areas, cooling) - think how pleased you'll be with yourselves!

For many years.

If heat pump system for heating and cooling is possible, you might consider that - it costs more to build, but you'll enjoy big time savings over the years. Needs supplementary heat source if you get temperatures under (I think) about 0 Fahrenheit in your area - check out those figures.

Good wishes as you set out to find your optimal system. I hope that you enjoy the system that you choose.

joyful guy

Windows...It never fails to surprise me how someone can do "everything right" when designing a new home by installing radiant heat and building with SIPs and then skimp on the windows.
Windows are potentially THE major drain on home energy usage, particularly when considering a well constructed and tight house, so it pays to invest in the best possible window system that you can afford...one that maximizes performance for your particular location and environment.