Profiled in ECO-STRUCTURE in September 2009, the Department of Energy’s Research Support Facility at the National Renewable Energy Laboratory (NREL) houses over 800 people and a data center in 222,000 square feet. The goal in designing the structure was to create the largest commercial net-zero-energy building in the country and provide a blueprint for a net-zero-energy future.

Integrated into an existing site, the building is shaped to optimize passive energy strategies. The main office wings are 60 feet wide to capitalize on daylight and natural ventilation. Overall, 92 percent of all regularly occupied spaces are daylight and all office spaces have 100 percent outside ventilation air delivered via an underfloor distribution system that is decoupled from the space conditioning system. Two long office wings are oriented on an east-west axis and are linked by a connector space housing the lobby and conference facilities. The building is designed to create its own electricity, heat its own ventilation air with a transpired solar collector, and shade all windows in the summer.

Building lighting is integrated with daylight-control systems, occupancy controls, and high-efficiency fixtures. Thermal comfort is addressed through thermal mass, radiant slabs, night purging, and natural ventilation. Underneath the two office wings, a larger thermal labyrinth stores heat from transpired solar collectors on the south building façades, This head is then used to passively temper the ventilation air during the heating season. In addition, the labyrinth serves as a thermal sink for reject heat from the data center on site. An on-site photovoltaic system that is split into two systems—one on the roof, and one over the parking structure that is scheduled to be installed later in 2011—is sized to provide 1.6MW of power, and the building’s energy model predicts an energy use intensity of 33kBtu per square foot per year.

The building is designed for a service life of 50 years or longer, and a 138,000-square-foot extension is currently under way. This expansion is predicted to be 17 percent more energy efficient at a cost that is $13 per square foot lower than the cost of the original building.

By the numbers:

Building gross floor area: 222,000 square feet
Number of occupants: 822 (plus 60 visitors)
Percent of the building that is daylight: 66
Percent of the building that can be ventilated or cooled with operable windows: 67
Total water used, indoors and outdoors: 791,202 gallons per year
Calculated annual potable water use: 3.56 gallons per square foot per year
Total energy (MBtu per yr): 7,281 (simulation case)
EPA performance rating: 100
Percent total energy savings: 46
LEED rating: Platinum, LEED-NC v.2.1/2.2

For more information on each project, including extended slideshows, click on the individual projects in the sidebar at left. To access a database of past Top Ten projects, visit ECO-STRUCTURE will be covering the 2011 COTE Top Ten projects in depth in its July/August issue.