Iris Communications, Inc. World Headquarters Heating and Ventilation
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	Ducts pass through interior spaces so they don't require insulation or elaborate air sealing measures.
	Hydronic heat tubes will carry heated water through a concrete floor. This floor is framed with 9-1/2 I-joists spaced 19 inches apart to carry the load of the three-inch concrete floor. Many radiant floors are 1-1/2 inshes think. The extra mass of the three-inch concrete stores heat and reduces heating system cycling.
	Water is heated with a high-efficiency heat pump. This two-stage York Stealth heat pump has enough capacity to meet all the home's heating needs even when the outdoor temperature drops to 0° Fahrenheit. A unique feature of this system is the Aqua Products heat exchanger (below the outdoor unit) that transfers energy from the heat pump to a gylcol and water solution that distributes heat through the building.
	Aqua Products calls their technology a reverse cycle chiller. An important part of the system is a water storage tank, which acts as a "thermal flywheel". The heat pump's job is to keep the water in the tank between 80°F and 100°F. This thermal storage reduces heat pump cycling, supplies heat to the home during times of low demand and offers a heat source for the defrost cycle (instead of chilling the house). There are three zones corresponding to the three occupied levels of the home. Each zone has it's own thermostat and pump. The system also produces chilled water for cooling. In the dry climate of Central Oregon, the chilled water can be circulated through the slab. (In larger homes, a fan coil and duct system could be added to increase cooling capacity.)
	Super-tight construction makes controlled ventilation essential. SunTerra's mechanical specialist, Joe Stone, installs the Stirling Recouperator DX 200 energy recovery ventilator. This unit pulls moist air from bathrooms and the laundry room and sends it outside. Along the way, heat and moisture are transferred to the incoming air stream. The unit is 95 percent efficient, balances the two air streams automatically and uses high-efficiency electric motors.
	The ERV and all its ducts are located inside the building's insulated envelope. The ERV shares a mechanical closet with another fan that recirculates solar heat from the great room to other parts of the house. Both ventilation devices share delivery ductwork, which makes for a crowded closet.
	The efficiency of the heat pump unit was measured by Energy Star staff. The coefficient of performance (COP) at that time was calculated to be 3.5 at 49°F.
	Christopher Dymond, Oregon Department of Energy energy analyst installed data collection equipment to track actual energy use and building performance. His preliminary efficiency calculation put the COP greater than 4.0 at 50°F. This efficiency compares favorably with geothermal heat pump systems -- at a fraction of the cost.