There is no practical technology for passively shielding a heating element to virtually eliminate H-field EMF. The only effective approach is "active shielding". This means canceling the H-field of one heating element with the H-field of another parallel element. Watts Radiant electric heated floors use this approach with a complex wire made of two sets of heating element constructions; running them in parallel with a patented helical twist. Here is a link that might be useful: Electric Radiant Floor Heating

Wianno - it's honed black Brazilian slate. John and David - thanks for the advice. I talked to the contractor last night and he said he thinks that if we reinstall one of our radiators, we might be better to go with electric and just use it as needed, rather than having an always-on hydronic system.. I will ask about this at the site John suggested, but any thoughts about this? Right now with the demo we have been down to one radiator, and even with a week of below zero temps last week, the kitchen stayed very comfortable.

Based on my experience, I'd say that trying to divide an open area into two zones won't work. We built a 1000 sq ft addition of several rooms and and an open area - it has its own furnace and a new furnace was put into the existing structure at the same time. The connection between the areas is a wide-ish hallway. When both furnaces are on, the house is evenly warm. Without closing doors, it's not feasible to have the heat on on one side but not the other because the cold air mass on the "off" side keeps the "On" part of the house from warming up. The areas most distant from the border will get too warm as the system tries to compensate, and the areas near the border stay cold. Neither cold nor warm stays put because you want it to. In your plan, I think there would be a constant flow of warm air to the cold area along the ceiling and cold air to the warm area along the floor. Not a question that you asked, but your plan suggests you're going to have a very dark region by the dining room and stairs. You've got a long wall with no windows between the living room and the family room, and the fireplace will block light coming from the front. Good luck

The house I am currently building is ICF, and I love it. I considered SIP's, especially steel SIP's, but it wouldn't have been feasible for one old man (me) working alone. I went with a conventional wood floor structure and roof trusses. I did build everything to FL wind standards, even though I am in upstate SC. If money were no object, I would have still used ICF, due to the structural strength, but I would have done a suspended concrete floor, and used light steel framing for the roof, with steel SIP's for the roof. Not only rodents, but termites have been shown to tunnel through the foam for considerable distances. Either critter can get through a conventional OSB SIP, and of course, ICF, although they can't get through the concrete in the ICF to actually get inside. The reason for all of the steel and concrete is that it doesn't rot, burn, or get eaten by anything. Also, wood quality these days is dismal. It took me a LONG time to strap and shim my ceilings to get them flat. I used steel framing for the interior walls to get them straight and flat. The inside of the ICF was already perfectly flat. BTW- there are fastening points every 8" with ICF, so attaching drywall and other items to the wall is as easy, or easier than wood framing.