I am working on the plans for a house I plan to build. It will be my retirement home and I plan to pay a little extra and build it very energy efficient, foam block basement, sprayed closed cell insulated walls, high efficiency windows, etc. I am looking at energy efficient HVAC systems and have run into some confusion. The house will be one story, 1700 sqft., and I also plan to heat and use the basement. I have calculated the heat loss and with the values for the high R values in the walls and ceiling I come up with less than 50K BTUs heat loss. The problem is, the CFM of the high efficiency furnaces I have looked at is much lower than the CFM needed for 3200 sqft of conditioned space.
When the time comes I will get a HVAC professional to help plan and install the system but I, at least, would like to know what I need and make sure the person I hire knows what they are talking about. Do I reduce duct size to match the CFM of the furnace, need more than one furnace, increase BTUs to get enough CFM?
I will also have an energy recover ventilator removing air from bathroom and kitchen areas and bringing fresh air to the return duct.