Students from Washington University in St. Louis believe their 2017 Solar Decathlon entry will be standing a hundred years from now.
Courtesy DOE/WU

The Solar Decathlon is a biennial collegiate competition challenging student teams to design and build full-sized, solar-powered homes with an emphasis on sustainability. This year, 11 teams from institutions across the world will participate in 10 contests that emphasize innovative design, energy efficiency, water use, resident comfort, and market potential. The DOE-sponsored competition, which is open to the public, will be held in Denver from Oct. 5-15. In this daily series, BUILDER takes a look at the innovative features of each of the homes.

Students from Washington University in St. Louis believe their 2017 Solar Decathlon entry will be standing 100 years from now. They designed Crete House, a precast concrete home, as a sustainable and stylish alternative to traditional wood-frame construction.

Designed for resilience, Crete House is made up of concrete sandwich panels consisting of 4 inches of standard concrete, 5 inches of insulation, and 1 1/4 inches of ultra-high-performance concrete (UHPC) on the exterior. UHPC is six times stronger than conventional concrete, the team says, and reduces the overall weight of the wall to allow for more design flexibility. The UHPC also acts as thermal mass, storing and slowly releasing heat from the sun.

Crete House offers protection from fires, extreme weather events, moisture, mold, and insects, according to Team WashU. Its concrete panels are manufactured in a factory and assembled on site with bolts instead of traditional field welds. This dry connection method both reduces material waste and simplifies field assembly.

On the exterior of the home, large concrete gutters extend out from the main structure to support shading materials in the outdoor living area. Plants line the gutters, which drop into a series of stepped, horizontal plant beds.

The gutters both collect water and direct it to storage tanks, from which water can be pumped to plants as needed. Team WashU designed the hydroponic system with self-sufficiency in mind, offering residents the possibility of growing fruit, vegetables, and herbs year round.

Inside, Crete House features a radiant heating and cooling system in the floor and ceiling. Hot water circulates through piping within the concrete panels, and heat can be redistributed to other areas of the home. A water-to-water heat pump acts as an “all-in-one” unit which both provides hot water for the radiant system and hot or chilled water for domestic use.

Crete House was designed for two research scientists stationed at WashU’s Tyson research center, to be a test bed for further sustainability research and education. If will be the first building in a net-zero eco-village planned for the Tyson Research Center.