Here in Minnesota, this is a very popular option and even though it gets cold here, fuel saving is not the main consideration. The main reason most people install radiant floor heating in a basement is comfort. Basements in North America will range in the 60s with wall and floor surfaces ranging in the mid-50s year round making most basements more like root cellars than living spaces.

The simple and proven recipe for damp cold basements is to heat the floors. You can do it with a dedicated forced air zone, but the results can be less than satisfactory, as warm air does not want to go down and cold air will not go up i.e. when heating, the upper level will get more heat than intended (especially if the staircase to basement is open) and cold air will tend to further cool an already cold basement).

The answer is; since you will be insulating the basement floor with a minimum of R10 and pouring a slab, you will have the perfect radiant panel, lacking only PEX tubing and a heat source.

If you have relatively inexpensive PEX tubing installed in the slab, you will be Radiant Floor Ready® for future comfort and added home value, without assessment, since it is not yet functional. When you are ready to use the basement, the properly sized water heater "Suitable for water (potable) heating and space heating" can work as a combi space and water-heating appliance.

Enhanced subsystems can add outdoor reset lowering fuel bills and adding to comfort. Many homes will suffer cold floor syndrome on the main level because of cold basements, so if you heat the basement floor, the floor above will naturally be warmer and more comfortable.

I regularly use condensing water heaters in my designs, heating domestic hot water and space with a foot print 22" inches in diameter, quiet, clean and great performance in one simple, reliable package. Condensing water heaters feature sealed combustion, PVC venting and 96% thermal efficiency just like a high efficiency furnace. This combi heater also eliminates the necessity for an uncontrolled combustion air duct and the loss of conditioned air by noisy direct vent water heaters.

Insulating the basement walls to at least R20 (with insulated concrete forms, in new construction) and putting R16 in EPS (not XPS) under the slab would cut the heat loss of the basement sufficiently to keep it pretty comfortable with a 68F first-floor above, even without actively heating it.

The heat loss of the first floor won't change appreciably by adding radiant (or other) heating to the basement, but the heat loss to the whole building would be reduced (by double-digit percentages, in most instances), by air-sealing and insulating the basement. First floors have more windows, doors, and air leaks, with colder peak exterior temps than sub-grade soil. But uninsulated the sub-grade portions are a constant and significant heat drain, and the above-grade walls have less than R1 of concrete, making it more than 10x as lossy per square foot to the outdoors as even code-min exterior wall on the first floor. Heat loss out of the first floor to the basement is a small fraction of the first floor losses. That would go away by heating the basement, but it can also be reduced nearly as much by insulating the basement reasonably, making the first floor more comfortable by raising the coldest-days floor temps a few degrees.

If you build with ~R20-ish ICFs the cost of building the foundation won't be dramatically different, and it'll be cheaper than insulating the basement by other methods. (such as: http://www.buildingscience.com/documents/reports/rr-1003-building-america-high-r-foundations-case-study-analysis ). Insulating the slab is cost adder over code, but it's a comfort-enhancer whether you did radiant or not, and would be absolutely essential to do a radiant slab. There is no harm in running PEX in the slab to make it "Radiant Floor Ready® for future comfort" as MA suggests, and would be well under the $5K quoted for the whole shebang.

But spending some money on a higher-R foundation walls & slab may prove to be comfort-enough. It has, in my case, even without the slab insulation, which would require me jackhammering out the existing slab to retrofit. I have ~ R20 on the walls, nothing under the slab, and the basement stays above 65F all winter with ~68F on the first floor. The slab stays pretty cool though 57-60F, depending on where it's measured. Subsoil temps in my neighborhood are ~48-50F, which is fairly similar to Rochester's subsoil temps, but clearly YMMV. With even R5 under the slab I bet the whole basement would run a couple degrees warmer.

If even the PEX you might not ever use is a not-starter, you always have the option of going with radiant-ceiling in a well-insulated basement.

Thanks for the replies.

It sounds like the heating needs of the upper floors won't be greatly effected by running the radiant system in the basement, so we will likely not install a radiant system in the basement until we finish the basement and spend more time down there. In the meantime, we will likely install the tubing in basement slab (with under-slab insulation) upfront when the house is built to give us the flexibility to add the radiant system later.