Room and water heating

What should we do for heating?

Reading through the littany of heating advice for well insulated homes, many people advise against radiant in-floor heating. However this is what we're planning with our slab-on-grade ground floor. I want to make the most of the thermal mass in the slab and hopefully heat it with solar heated water. We'll have a wood stove for back-up and possibly a base board heaters in the upstairs rooms and the washrooms.

In principle it would be nice to have the in-floor heating (the water type) on the second floor as it could absorb heat during the summer day and then at nigh we flush out the pipes with cool water and send the warm water to the garden. This is only theory though.

Then thinking about solar water, should we have three water lines in the house? In the winter there would be cold, warm (solar) and hot (small electric tank). Then in the summer we would turn off the tank and the solar water would be much hotter. If this could work then we would use the winter solar water to also warm the ground floor.... just a thought.

While I'm on the topic, I don't like to waste water while I wait for it to heat up coming out of the tap. One solution I've seem is to have it slowly recirculate by going back into the cold stream and back to the water heater. Of course then you lose efficiency by mixing the hot and cold. So I'm considering installing the hot water as one large loop throughout the cabin. Recirculating back to the heater/solar heater independent of the cold water stream.