Solar Decathlon 2015: INhouse

Solar Decathlon 2015 just wrapped up in Orange County, California. Sponsored by the U.S. Department of Energy, the Solar Decathlon challenges collegiate teams to design and build a small house powered entirely by the sun.

INhouse was the entry by California Polytechnic State University, San Luis Obispo. INhouse placed 3rd overall and did particularly well in the architecture and market appeal sub-competitions.

Part of the home’s curb appeal is due to a covering of redwood strips. The redwood screens are not just for aesthetics though; they also cool the house by shading the walls. The screens are more opaque where the sun hits the house hardest and more transparent on other sides. According to Cal Poly’s analysis, the screens cut the cooling load by nearly 5%.

As the teams build their houses near their respective campuses and ship them to the competition site, most adopt a modular approach. That was the strategy Cal Poly used for their 986 ft² (91.6 m²) entry, splitting INhouse into three modules. The center module is the home’s mechanical core, containing the kitchen and bath along with all the HVAC and electrical equipment. The core is flanked by a living area module to the south and a bedroom module to the north.

The living area module is open to the kitchen, creating a nice T-shaped open plan layout. The size of the living area may be a bit bigger than many of you would prefer but keep in mind that the Solar Decathlon houses are designed for hosting tours and large gatherings as that is part of the competition. With the design of INhouse, it would be quite easy to make the living area and bedroom modules longer or shorter.

A 15’ folding glass wall opens the living room to a screened patio for seamless indoor-outdoor living, which certainly makes sense in a temperate climate. The patio is enclosed by sliding redwood screens and is shaded by an array of photovoltaic panels. The panels are a state-of-the-art design that also absorbs reflected light from below, giving a small boost to the direct sunlight hitting the top sides.

The bedroom module is a large room that also contains a flex space, with the furniture arrangement defining the two functional areas. The flex space could obviously be used for many things but has been set up as a home office for the competition.

It would be nice to be able to turn the flex space into a second bedroom but the floor plan layout doesn’t make that easy as the bedroom half is reached by going through the flex space. To split the room into two bedrooms, you’d also have to allocate some space to a hallway, making one or both bedrooms much smaller. So, the flex space isn’t as flexible as it would have been if the door was located more in the middle of the room or if an allowance had been made for adding a second door elsewhere. One possible solution is to just shift the entire bedroom module to the east.

At the back of the house there is a constructed wetland for treating the home’s grey water. The cleaned water is used to irrigate the landscaping, eliminating any need to use fresh water for that purpose. You can read more about the design and technology used in the house on the INhouse website.

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Photographs by/courtesy of Solar Cal Poly and by Thomas Kelsey courtesy of the U.S. Department of Energy Solar Decathlon.

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