The Dream of the All-Electric House, Revisited
Not General Electric’s home of the future, this demonstration project, scheduled for construction in 2010, envisions a home that is completely energy neutral. An eight kilowatt solar array, grid connected and net metered, will produce all power necessary for domestic and transportation purposes, without any on site carbon emissions. The owner, who has been working in the solar industry for over twenty years, is committed to, ‘getting off the pipe, a house without a gas meter.” The basic design strategy is to create a responsible intervention in an historic setting, acknowledging the context while at the same time embracing a contemporary vision of space and function. It includes a structure with ample roof area for the panels and a highly efficient envelope. The space planning places open living spaces at the rear of the house directly adjacent to the garden. These rooms employ ample, south facing glazing for maximum solar gain. On mild days, exposed concrete floors with radiant tubes convey passively collected heat to the north facing portions of the house via a small re-circulating pump. We have specified Marvin wood windows with High-R-Tripane glazing and sprayed, Biobase, soy foam insulation for R-19 walls and an R-40 roof. This creates a tight enclosure while also accounting for existing, historic “blind walls” and the inherent problems with air and moisture infiltration that they present. A three-story stair well, topped with operable skylights is a dramatic vertical space and creates a “heat stack,” providing all cooling necessary for the moderate San Francisco climate. The mechanical systems are based on the “all electric” concept. In the active heating mode, a 2/3 ton, electric heat pump provides hot water for the floor system. A second heat pump provides domestic hot water. LED fixtures and high efficiency appliances lower the total electrical load, while a plug-in hybrid charges in off hours to balance production and consumption cycles with the net metering approach. In an effort to embrace a holistic approach to sustainability we have included a gray water reclamation system. It will provide irrigation for a shared, backyard vegetable garden and for drought tolerant, landscape features both at the yard and the street. In this urban setting, this project represents an initial attempt to do more than “green” the structure, we are working at the level of lifestyle, beginning to think about transportation, food production and community as component parts of the architectural response.
Architect: , LSarc
Associate: Karen Andersen, LSarc
Structural Engineer: Shaun Monyihan, SEMCO
Mechanical Engineer: Bill Dakin, Davis Energy Group