Iowa State University

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Annette Hacker, director,
(515) 294-3720

Office: (515) 294-4777


Iowa State University Solar Decathlon facts and figures

Interlock House

Iowa State University's Interlock House offers a viable choice for sustainable development. It could fit into an existing neighborhood or vacant urban lot and serve as a retirement cottage. (Downloadable photo)

About the Interlock House

  • Size: 800 square feet
  • Dimensions: 19 feet x 38 feet
  • Height: 16 1/2 feet
  • Structure: 2 x 6 wood frame construction with modifications for energy efficiency
  • Windows: Triple panes with low-emissivity coating to control heat transfer and non-conductive gas between panes. Frames are fiberglass.
  • Insulation: Biofoam spray
  • Insulation values: Window R-12, Walls R-49
  • Floor: Warmboard radiant sub floor
  • Heating system: Solar thermal evacuated tubes using radiant heating; passive solar; and a student-designed, custom passive-tracking system of photovoltaic louvers (above the sun porch) that will follow the sun, maximizing solar energy absorption.
  • Cooling system: Solar thermal evacuated tubes using chilled-beam cooling and solar-fired absorption chillers
  • Dehumidification: Liquid desiccant system custom designed by ISU students
  • Water heating: Solar thermal evacuated tubes, radiant floor heat
  • Electricity: Solar photovoltaic modules (solar panels), both thin film and crystalline
  • Lighting: Interior -- LEDs, fluorescent and passive day lighting; Exterior -- solar powered
  • Exterior cladding: recycled barn boards
  • Anticipated energy production: 1114.78 kWh of electricity per month on average
  • Anticipated energy consumption: 563.16 kWh of electricity per month on average.

About ISU's project

  • Number or students: 75
  • Number of faculty: 17
  • Number of academic departments: 11
  • Number of colleges: 4
  • Classes working on the project this semester:
  • Architecture design studio
  • Construction engineering independent study
  • Mechanical engineering independent study
  • Electrical engineering senior design
  • Materials science engineering senior design
  • Journalism and mass communications portfolio class
  • Furniture design
  • File to fabrication design
  • Ceramics
  • 3-D media and animation
  • Budget: $800,000, which includes in-kind donations, transportation of the house to and from Washington, D.C., and graduate assistant salaries. $100,000 came from the DOE, and the students are raising the remainder of the funding from ISU colleges, departments and institutes; gifts-in-kind; and cash gifts from individuals, corporations and organizations.

About the Solar Decathlon

In January 2008, the U.S. Department of Energy selected 20 teams of college and university students to participate in the fourth Solar Decathlon, a competition to design, build and operate the most attractive, effective and energy-efficient solar-powered house.

An international educational project, the Solar Decathlon calls attention to the ever-increasing need for energy, while showcasing solutions for using energy more efficiently and using energy from renewable sources.

The 20 teams are:

  • University of Arizona
  • Cornell University
  • Technische Universitat Darmstadt (Germany)
  • University of Illinois at Urbana-Champaign
  • Iowa State University
  • University of Kentucky
  • University of Louisiana at Lafayette
  • Universidad Politecnica de Madrid (Spain)
  • University of Minnesota
  • Missouri University of Science and Technology
  • Ohio State University
  • Pennsylvania State University
  • Universidad de Puerto Rico
  • Rice University
  • Santa Clara University
  • University of Calgary/SAIT Polytechnic/Mount Royal College (Canada)
  • Boston Architectural College/Tufts University
  • University of Waterloo/Ryerson University/Simon Fraser University (Canada)
  • Virginia Polytechnic Institute
  • University of Wisconsin-Milwaukee

In October 2009, the houses will be judged, then open to the public in a solar village open to the public on the National Mall, Washington, D.C.

Houses are judged in 10 contests:

  • Architecture
  • Market viability
  • Engineering
  • Lighting design
  • Communications
  • Hot water
  • Appliances
  • Home entertainment
  • Comfort zone
  • Net metering

Student participants are called decathletes.


Interlock logo

Students begin building ISU's solar house for Solar Decathlon competition

Quick look

The Solar Decathlon team continues to seek additional sponsors and donations. Among the items still needed are HVAC ductwork, plumbing, faucets, kitchen appliances, light fixtures, drywall, hardwood flooring, bathroom wall tiles, decking, furniture, bedding and Iowa native plants. More information is online.