System integrative design in the 2009 Penn State Solar decathlon net-zero energy home

Informed decision making via an integrative design process and iterative energy simulations (early and often) is crucial during the development of a building design. We report the process and results of energy simulations for the 2009 Penn State Solar Decathlon home, Natural Fusion. The team's home entered the 2009 Solar Decathlon competition organized by the U.S. Department of Energy. According to design criteria of the Decathlon and team concept, we show how iterative modeling can inform decisions throughout the design and build process. Unique systems integrated into the home include a green roof integrated photovoltaic system (GRIPV), a pump-less solar hot water system, a large southern façade for maximum solar gain, a phase change material integrated into the walls and ceilings with a water filled floor system for high thermal capacitance throughout the building while maintaining a low transportation weight, and a close evaluation of loads and demand side management integrated with a user feedback system.