4. Plumbing

All fixtures are low flow and WaterSense to decrease water usage in the house. Virtually all of the pipes are concentrated in a "mechanical wall" or "Core Wall" in the center of the house to reduce heat loss from warmed water.

Hot water is generated by the geothermal unit taking heat out of the house in the summer and using the excess heat in the winter to produce hot water.  This is done by the geothermal unit more efficiently than a resistance hot water heater or even a heat pump hot water heater. If the geothermal unit cannot produce enough heat, there is a heat pump hot water heater that will keep the water up to temperature. This is actually more efficient than a dedicated solar hot water heater. The 100 gal tank to the left has cold water from the ground preheated by the geothermal unit and the grey/red tank is the Heap pump hot water heater that only runs to maintain 120 degree water for bathing etc. 

Also the Core Wall or Mechanical Wall reduces hot water heat losses by having short insulated runs of piping. It also allows for a hot water recovery system on the drain pipe. This uses warm water leaving in the drain to heat water that is coming in from the water supply to the house. This energy otherwise is just wasted. This system increases in efficiency if larger amounts of water are being used continuously. We did not put In this system as for us it offered little gain with the amount of water that we use.