The CRETE House

The U.S. Department of Energy Solar Decathlon is described as a “life-changing competition for collegiate students and an intensive course in sustainability for consumers”. Participating student teams spend almost two years designing and building solar-powered houses that are cost-effective, energy-efficient, sustainable and attractive.

At the 2017 competition in Denver, Colorado, “Team WashU” (100+ students from the Sam Fox School of Design & Visual Arts and School of Engineering & Applied Science at Washington University in St. Louis, Missouri), secured second place in the Architecture category for their unique project called “The CRETE House”, an innovative, 995 square foot structure built entirely with prefabricated concrete. This includes an energy-efficient cladding system consisting of six large (12 ft x 22 ft wide), thin (1 inch) precast sandwich panels made from Ductal® Ultra-High Performance Concrete (UHPC).

Oversized gutters provide shade and extend the living space outdoors, while a water collection system and vertical planters support hydroponic gardening. The design also demonstrates that concrete is a viable, sustainable building material and a beautiful, highly durable alternative to wood construction. Thanks to its ultra-strong envelope, the home is extremely resilient against fire, moisture, mold, insects, seismic activity and harsh weather conditions.

Team WashU worked with the Precast/Prestressed Concrete Institute (PCI) to design and cast the Ductal® sandwich panels, which are about 30% lighter than standard precast concrete panels. The panels are connected with bolts, which contribute to significantly reduced labor and material waste compared to traditional connection methods. Altogether, five inches of insulation was placed on top of the 1 inch Ductal® panel. (Typical sandwich panels have 3 inches of insulation because of the 3 inch concrete layer replaced by Ductal®).