During the summer, the only heat demand is for domestic hot water. Only the smaller bank of solar collectors will be operational. The larger bank is drained and idle. All the heat from the small bank will go directly to the 300 gallon storage tank. If/when its temperature exceeds 160 degrees, then the collector fluid will be directed through a ground loop to dump the excess heat. This is necessary to prevent the collector fluid antifreeze, propylene glycol, from breaking down. Maybe someday there may be a hot tub for all seasons but winter, eh?

Because of the high levels of insulation, low infiltration rate and large internal thermal mass, the house will require very little cooling in our climate. However, there are apt to be several periods during the year when some active cooling is desirable. We want to minimize the use of electric and complexity of equipment to accomplish this goal. The first strategy, during hot days and cool nights will be to exhaust hot air and pull in cool air. This will be done by moving hot air off the ceiling of the first floor to the second floor and drawing in cool outside air. At the same time, a small fan in the attic will pull hot air off the second floor ceilings and expel it outside. This is a low flow, low power, quiet system and most nights it will be sufficient. During hotter periods, we can circulate water through the first floor thermal mass. This water temperature will be set above the dew point by varying circulator speeds extracting heat from a small tank and dumping it into the earth. Yes, we have split air conditioner in the Active Area for backup if necessary, but I expect it will rarely be used.

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