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Orange County Great Park, Irvine, California
October 8-18, 2015

Team Orange County: University of California, Irvine; Chapman University; Irvine Valley College; and Saddleback College

Team website:

Teaming up for their first U.S. Department of Energy Solar Decathlon competition, the University of California, Irvine; Chapman University; Irvine Valley College; and Saddleback College designed an innovative, net-zero-energy house that draws inspiration from the California state flower: the golden poppy. Like the flower, Casa Del Sol is drought-resistant and architecturally adapted to Southern California. It features an open design with a flex floor plan and separate studio for multigenerational living or a possible rental.

Design Philosophy

Casa del Sol's architectural features—including a south-facing veranda, halo with retractable tensile structure, and eastern brise soleil—passively maintain a comfortable temperature by allowing sunlight into the house during the winter and providing shade from the sun during summer. Strategically positioned windows open to capture southwestern breezes.

Casa del Sol's conditioned space comes in at just under 1,000 ft2 and is mechanically managed by a radiant heating and cooling system coupled with rooftop solar thermal. Grey water is recycled and storm water is collected for use in the xeriscaped garden. An AC/DC bidirectional inverter allows the house to run on either electrical system, maximizes energy produced from solar panels, and makes Casa del Sol smart grid-ready.



    • A halo structure with an adjustable shading component above the outdoor living room regulates temperature and natural light while maintaining a comfortable environment in the most energy-efficient way possible.
    • The grid-tied bidirectional AC/DC inverter saves energy and enables future smart grid integration.
    • A hydromatic dryer uses solar thermal energy to supplement heating for the drum.
    • The studio unit enables residents to comfortably house aging parents, returning college students, or an income-generating renter.


    • To improve indoor air quality and the lifecycle of materials used, Team Orange County followed the Living Building Challenge's materials red list—a compilation of harmful-to-human chemicals and materials.
    • To address California's drought, Casa del Sol incorporates greywater recycling systems in conjunction with rainwater catchment to irrigate the xersiscaped garden and provides occupants with fresh, organic produce year-round  through an aquaponic garden that requires 90% less water than traditional gardens.
    • Operable windows, automated by an energy management control system, open and close according to weather patterns to maintain temperature without mechanical heating, ventilation and air conditioning.
    • A personal 3-D printer and small-scale thermoplastic recycling system allows residents to break down printed objects that are no longer needed and reuse the material to generate new products such as household tools, creative decorations, and parts for simple home repairs.


    Market Strategy

    Casa del Sol's private studio unit, with its own bathroom and kitchenette, can be used as supplemental living space for family members—a returning student, a grandparent, or an extended relative. Equipped with its own utilities, the studio can also be rented to economically support the homeowners.

    What's Next

    After Solar Decathlon 2015, Team Orange County hopes to find a local site where Casa del Sol can be maintained as a living laboratory to educate and engage the public in innovative approaches to sustainability.


    Greg Washington

    Neither the United States, nor the Department of Energy, nor the Alliance for Sustainable Energy LLC, nor any of their contractors, subcontractors, or their employees make any warranty, express or implied, or assume any legal liability or responsibility for the accuracy, completeness, or usefulness for any purpose of any technical resources or data attached or otherwise presented here as reference material.