I am in process of building a home in the Pacific Northwest. The house is designed to be heated almost entirely with passive solar heat. However, we would like to have supplemental heat just in case. It does occasionally get cold enough here to warrant it. I am trying to figure out what would be the most efficient option. The slab is already poured, so no radiant in there, but it's a traditional stick frame house otherwise. I am not interested in a forced air system, I'm looking for simple, flexible heating options. Thanks!

Panel radiators, would be my first suggestion if suggesting things blind. economical, fast response, easily zoned without wires, sized for low temp operation for efficiency. downside is that they are visible, wall space consuming emitters.

wood stove, gas stove Rinnia has a nice fairly efficient model, gas wall furnace, and then you have hydronics.. as Rob says panel radiators from buderas, runtal, and others but you will need a hot water heating system installed. If it is only going to be used a few days out of the year than I would look at a gas stove, if no gas than there are electric radiant panels http://www.electricheat.com/index.html, or electric boilers to drive a hydronic system...Eric

How much supplemental heat do you anticipate needing? (and how often?) If the duty cycle & load are low enough, the higher efficiency & expense of more sophisticated systems aren''t warranted. (Many PassiveHouse designs use electric resistance heat in the ventilation air.)

I'm assuming you have a tighter & higher R envelope than the typical "traditional stick frame" PNW standard 16" o.c. 2x4s with a R13 fiberglass batts, no foundation insulation, if you're supporting the bulk of the load with solar(?).

And your fuel options are... ?