fonzy, what kind of heating/cooling system are you putting in, warm forced air with gas, FA with heat pump, radiant & geothermal? The type of system you are using will make a difference in what control system you put in. What kind of climate are you in? What parts of the house face north and south?
Here's my experience with a single floor home, ICF with spray foam on the underside of the roof deck and totally sealed and conditioned crawl space. I have a Daikin heat pump with the air handler in the crawl space. It has a variable speed compressor and cycles on and off only about once per day. I use the crawl space for the supply plenum and the attic for the return air. Registers are in the floor around the perimeter. Return grills are in the ceiling around the perimeter. The fan in the air handler runs continuously so I have constant air circulation throughout the entire house from floor to ceiling in every room with some room to room air movement. In summer and winter both, the temperature in the living room is almost always 2 to 6° warmer than in the master bath and bedroom. The reason being is the living room has south facing windows and wall and the bedroom and bath are on the north side. There's enough solar heat coming in through the windows and walls on the south side to warm up the living room. The south walls get warmed by the sun and of course the north walls don't. The constant air circulation isn't enough to transport the heat from the south to the north side of the house. What I do have is fairly constant temperature from floor to ceiling because of the full time circulation. The south windows are almost totally shaded in the summer, with a high percentage of sun exposure in the winter.
My assessment at this point is that ICF construction not only holds heat very well in the winter, and out in the summer, but also is very effective in capturing solar heat. Also the heat load in the house is so low in the winter that the heat generated by everyday living activities (cooking, TV, computer, light bulbs, bodies, etc.) is a significant contributor to warming the house. The part of the house where most of that heat is generated is going to be warmer. Keep in mind that close to 100% of all the electricity that comes into the home gets converted to heat, and ICF keeps it in.
Work with your HVAC guy to map out as much as practical where all the heat is going to be generated in your house, both from solar and ordinary living, summer and winter. You may want to have not only separate temperature controls up and down, but some means of redistributing warm and cool air around the house.
In my book, based on my experience with one house, heating and cooling an ICF house is not as simple as heating and cooling a stick house. But it is a lot more comfortable!
