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Hi Bob, Here's some general considerations. Heat rises and cold air sinks. Use that to determine where you need to insulate for maximum efficency. Below ground temperature at 8ft is approx 50f� average in N. America. This is pretty consistant and doesn't change yearly. Typical earth is thermal stable at 2ft thick, meaning the 2ft of earth will not change temperature when exposed to air on either side of the wall and will thermal stablize at approx 70�f. As far as I know there is not a scientific explantion for this known fact but thousands of years of Adobe buildings has proven this fact indeed does exist. So if you have a consistant "unlimted" source at 50�f and out your outside air is at minus 40�f then you have a "constant" available heat gain of 90�f. 70�-50� = 27�f of heating required. (7� of inefficiency of typical air/liquid heat exchanger pumping loss. Liquid/liquid heat exchangers is typical 3�) A well designed simple HW solar collector in 60� abmient can raise 80gal of 55� inlet water in two hours to 180�. A typical human needs 3 air changes per hour to feel comfortable with-in a "closed room". So if your room was 20ft x 20ft x 8ft high you would need to move a constant 160cfm per hour. 20x20x8=3200x3=9600cft/20=480cfm/3=160cfm The faster you move air, measured in feet per minute (fpm), during the winter the colder you will feel from skin moister evaporation. A typical human feels comfortable at 70� at 50%rh. Drop the humidity to 40%@70� and a sweater will be needed. Drop that to 10%rh@70� and a jacket would be required while sitting. The reverse is also true. A room at 80%rh@70� then one would be naked to feel comfortable. I can see the wheels turning now! LMAO Outside Air tends to be drier during the winter, approx 30%rh is typical and 70%rh during summer. So humidify the rooms during the winter and refrigerate/condensate during the summer without changing room temperature. Preform all design calculations on BTU/hr requirments per "pound" of substance. If not then you will over/under design for both winter and summer comfort. My neighbor has a exposed foam roof. The birds just pick it to death. Looks like someone took a shotgun and blasted the foam after one year. T_Bone
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