the house will have an energy recovery ventilator. this device expels stale air from the house while intaking an equal quantity of fresh air. the zehnder ventilator that we selected does this at an efficiency of 83%.
the air intake can freeze during winter. to keep this from happening a small electric resistance heater can be installed or a brine loop can be used. the loop is made of plastic pipe embedded four feet or deeper in the ground and is at least 250 feet long. in the loop a glycol solution circulates, not brine after all. in my area the solution takes on the ground temperature of 55 degrees fahrenheit. the glycol finally passes through a radiator in front of the ventilator’s air intake. this heats the air going into the zehnder ventilator during winter, so no electric heat is needed. it also cools the air during summer. follows a picture of the pipe that carries the glycol solution. this pipe is about four feet under the surface. two feet below it is pipe carrying solution in the opposite direction. the pipe shown leaving the picture at the bottom goes to a coil, which will be unwound into the rest of the trench.