While reading about superinsulation, I came across the idea that a radiant concrete floor is a poor choice if you have really good insulation. The reasoning goes like this:
In a regular house you heat through walls, ceiling, windows, etc., so the floor is kept warm enough to keep bringing in more heat. This is one of the selling points of radiant floors: that warm floors feel good.
In a super-insulated house, if the thermostat is set for a comfortable air temperature, the radiant floor will rarely turn on, so the floor will always be cool. Walking barefoot on a cool concrete floor is unpleasant. On the other hand, if you turn up the thermostat to warm up the floor, then the air temperature will be too high.
Is this correct?
(I suspect this means that if you're going to super-insulate, especially in a mild climate, you should choose a floor material with low thermal mass and low heat conductivity, like wood or carpet.)