Visitor Center, Zion National Park, Utah
Zion National Park Visitor Center
Department of the Interior
National Park Service
In creating the Zion National Park Visitor Center, the National Park Service protected Zion's natural beauty by creating a sustainable building that incorporates the area's natural features and energy-efficient building concepts into an attractive design.
Since its designation as a National Park in 1919, the number of visitors to Zion's natural sandstone canyons, mesas, and rock sculptures on the Virgin River has grown steadily. Now, the National Park Service (NPS) has worked with the U.S. Department of Energy's National Renewable Energy Laboratory (NREL) to create a new visitor center to serve both the park's current 2.5 million annual visitors as well as visitors in the future.
Completed in May 2000, the Zion Visitor Center demonstrates the concept of "whole building design," a process that operates from a systems engineering perspective. Buildings designed in this way are conceived of as a system rather than as a series of independent components. The result at Zion is a sustainable building that incorporates the area's natural features and energy-efficient building concepts into an attractive design that saves energy and operating expenses while protecting the environment.
The Visitor Center uses 70% less energy than a typical building. And, because the building required no mechanical systems such as air conditioning, construction costs were lower. An energy-management computer that ensures all of the building's energy-efficient features are working together is key to the design of the building. The design also incorporates "outdoor" rooms that allow for a smaller building design, as well as lower capital and operation costs. Instead of adding fully enclosed rooms to the building, shade structures and existing trees create space for permanent displays.
In the winter most of the heat for the building comes from the sun. A Trombe wall traps the sun's heat between a pane of glass and a black selective coating.
Heat-storing masonry in the wall can exceed 100°F (38°C) and provide radiant comfort to visitors. Another source of heat is the thermal mass flooring. The colored concrete floor is heated by sunlight entering the building during the day. That heat is then released at night. A low-e coating on the window glass allows light and heat to enter but reduces the amount of heat loss to the outside. On days when the sun is not shining, radiant ceiling panels provide heat to the building. The roof is made of structural-insulated panels that sandwich rigid foam insulation between sheets of oriented strand board, thereby reducing heat loss in the winter. The roof insulation also keeps heat out of the building during the hot summer while passive down-draft cool towers help to reduce interior temperatures. Water sprayed on pads at the top of the towers evaporates and cools the air. This cool dense air "falls" through the tower and exits through large openings at the bottom of the towers. The energy-management computer controls the size of the openings at the bottom of the tower and can direct cool air into the building. Optimized overhangs, the length and position of which were determined by hourly computer simulations, shade high clerestory windows from the summer sun. The energy-management computer can open the high windows to allow hot air to escape while low windows near the doors allow cool air in.
The clerestory windows are a part of the lighting system as well as the heating and cooling systems. Computer simulations were used to carefully size the windows to collect the right amount of light. Heating and cooling needs were considered, maximizing direct sunlight in winter and minimizing it in summer. The building's energy-management computer adjusts electric light as needed, but the primary source of light in the building is daylight. When needed, the building uses only energy-efficient T-8 fluorescent, T-5 fluorescent, and compact-fluorescent lamps as well as LED exit signs.
Efficient design of the building eliminated large electric loads. On the south roof, a 7.2-kW photovoltaic (PV) array provides the majority of the electricity needed by the building. The PV system also provides uninterrupted power supply (UPS) for the building. During power outages, the energy-management computer will shut down nonessential electrical loads so that the PV/UPS system will support enough building operations to continue business for at least one-half hour without any additional PV power, or all day if PV capacity is available. Officials at Zion have negotiated a net-metering agreement with the local utility-excess power will be sold back to the power company for use elsewhere.