The Zion National Park Visitor Center design process was a collaborative effort between the National Park Service’s Denver Service Center and the Department of Energy’s National Renewable Energy Laboratory (NREL). Team members from NREL’s Buildings and Thermal Systems Center provided technical support to optimize the energy performance of the building. The Denver Service Center developed the architectural design with input from NREL about the energy implications of design decisions. This “whole-building systems integration” process started in pre-design and continued through to commissioning occupancy. The process resulted in a building that uses 66 percent less energy than code, and is virtually immune to the frequent power outages in the region. The project represents a synthesis of passive heating, cooling and daylighting, energy efficiency, and photovoltaic technology. Shading, natural ventilation, passive evaporative cool-towers, clerestories, trombe walls, direct solar gain, thermal mass, high efficiency lights, and 7 kilowatts of photovoltaics all work together to nearly eliminate loads. The project resulted in cost savings of more than $10,000 and 309 million Btu in site energy and 1 billion Btu in source energy.