I am strongly leaning towards using a radiant floor heating system for a single family home new construction project I am embarking on in early 2009.  I am new to home building in general and have been trying to educate myself but have been getting conflicting information.  For the climate I am building in (Ottawa, Ontario) where we have cold dry winters and hot humid summers, will I be able to get away with only radiant floor heating in the Winter?  What about cooling and dehumidification in the summer months, what are good complimenting systems for summer cooling?

The project may also include DX GeoThermal heat pump for the water heating/cooling and ICF construction for the entire home.

Any thoughts would be appreciated, thank you.

Consider doing radiant in the ceiling rather than in the floor. You could then use the same system for cooling. Not a simple back of envelope design situation, and there are many naysayers who will say it can't be done, but it can be and it works. I was going to do it until I dropped the entire geo source heat pump plan and went with a Daikin air to air heat pump that puts out heat down to 0F outdoor temp.

Go to www.bekausa.com for a start. There's a link there to a Univ of Pittsburgh prof who advocates heating/cooling via radiant with appropriate ventilation to maintain indoor air quality.

I also was planning on using DX Geo source heat pump in my ICF home, but the heat load calculation came out so low I couldn't justify the capital expenditure, hence the Daikin.

I put in floor heat in my entire house i just built. concrete on main and 2nd floor over the tubes. Prestige NG mod boiler. House is 2x6 frame with closed cell foam r 34 in walls I am in waterloo Ont my heating bill for the month of November was $80.00 2250sq/ft main floor 2250 basement 700 2nd floor and 700 in gargae which is also heated . I thought that was very good. I never had in floor heat until now and i would never build another house without it I dont know anything about radiant in ceilings But i know heat rises so common sense says its better off starting in the floor i Ran all duct work for my hrv and ac for summer

Allow me to share a correction to your statement. Heat travels from warmer to cooler regions by conduction, be it up, down, sideways, whatever. Warm fluids, usually air but also water, etc., rise by convection. The correct way to put it is, warm air rises, not heat rises.

Radiant heat, which is one part of the total electromagnetic radiation spectrum, travels in all directions just like light. In a radiant heated home the air temp is generally cooler than what the body perceives because the body is primarily receiving heat by radiation, not by its contact with warm air. The air is heated by all the objects in the room absorbing radiant heat, becoming warm, then in turn warming the air by contact.