Fourteen SunEarth solar hot water collectors mounted on the building’s roof supply the majority (about three-quarters) of the building’s hot water needs—for warming pool water and for radiant floor heating. Almost 2,000 feet of Kitec tubing embedded in the concrete floors and routed into the ceiling of the massage room move the solar-heated water throughout the building for space heating. A custom-built, insulated solar storage tank holds water heated by the collectors.
A propane-fired backup boiler helps when the weather is very cold and cloudy, but, for most of the year, the solar heating system is enough to warm the pool water and building. On average, Greg says that they spend about $100 per month on propane to heat the pool building and the water—less than one-quarter of the expense comparable facilities incur in this climate.
Along with the pool house came increased electricity use. The Chings decided to expand the existing PV system at the site to compensate. A 3.9-kilowatt (KW) PV array was set up just south of their home’s array, on a lower, longer, ground-mounted frame. At the same time, the battery bank was doubled in size, to increase the backup capacity for their home and pool house. Some of the circuits in the new pool house, like lights and the pump for the solar hot water system, were wired to a subpanel for battery backup, while the nonpriority loads were connected to the grid-fed service entrance panel.
A heat-recovery ventilator (HRV) improves the efficiency of the mechanical ventilation system by reclaiming energy from exhaust airflows. By using heat exchangers to heat or cool incoming fresh air, HRVs recapture 60 to 80 percent of the heat or cold that would otherwise be lost. Incoming and outgoing airflows pass through different sides of the heat exchanger (but are not mixed), allowing conditioned exhaust air to raise or lower the temperature of incoming fresh air. After passing through the heat exchanger, the warmed or cooled fresh air goes through the HVAC air handler, or may be sent directly to various rooms.
The Chings also incorporated many of the same efficiency measures they implemented in their home into the new pool house to keep its energy use as low as possible. During the day, the large windows admit ample natural light into the pool house, and tubular skylights in the utility room and office light these inner rooms. At night, compact fluorescent bulbs provide lighting. Insulating shades fitted to the large windows can be lowered or raised with the flick of a switch. Low-flow showerheads help reduce the water heating demand, and an ultra-low-flush toilet curbs water use. To minimize the loss of pool water due to evaporation and to reduce heat loss in the pool, a retractable cover is kept closed when the pool is not being used.