San Francisco Department of the Environment

Residential – Solar Heating & Electricity in the Sunset

Radiant Heating Heats Home Sunset District

“Toasty is not what people expect in a home in the Sunset,” but that is exactly how Ralph Lane describes his home on 35th Avenue. Having nearly completed a green overhaul of his home, including the installation of a solar water heating system in conjunction with radiant floor heating, Ralph said, “My living conditions are improved. I know what it’s like to walk into a home in the Sunset on a foggy day, and this is a different experience. People comment on it. People walk into this home all the time and say ‘Wow, it’s so warm in here!’” 

Installed by San Francisco-based Luminalt, the Heliodyne solar water heating system responsible for this warmth consists of 2 rooftop mounted Gobi collectors that are 40 sq. ft. each, along with a 350 gallon non-pressurized STSS solar storage tank in the garage. The system supplies solar pre-heated water to both the domestic hot water and radiant floor space-heating systems, with the capacity to add a third loop for spa heating in the future. Ralph notes that in addition to the tank, the hydronic system throughout the house and heat storing mass of the floor materials act as reservoirs to store the thermal energy collected from the sun.

Ralph and San Francisco architect Doug Jacuzzi of Soularch Design have also taken care to include a number of other energy and water saving strategies in his home. An ‘on-demand’ hot water system uses a low-energy, high-speed pump to bring hot water immediately to the taps when needed, saving energy and the cold water otherwise wasted when waiting for hot water to arrive. Two shower drain heat exchangers allow the cold water supply to absorb the heat from wastewater that would otherwise be lost to the sewer. Water from the roof and deck drains is reclaimed by channeling it to a large cistern in the backyard. The slick membrane used on the roof allows the system to collect moisture from the fog during summer, as well as rain in the winter. The reclaimed water will be used for landscaping, washing pets, and for growing a living roof and walls.

As if these perks weren’t enough, Ralph also enjoys the benefit of his 3.4 kW solar electric system, which has so far been generating more electricity than the home is using! This photovoltaic system is comprised of 18 SunPower 210 watt panels and a 4000 watt Xantrex inverter  that were also installed by Luminalt.


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