NREL Research Support Facility Certified LEED Platinum
The Research Support Facility on the campus of the U.S. Dept. of Energy’s National Renewable Energy Laboratory in Golden, Colo., was recently certified LEED Platinum for New Construction by the U.S. Green Building Council.
At 222,000 sq ft, the RSF leverages energy efficiency and environmental performance in a large-scale commercial office building. With 19% of the energy in the United States consumed by commercial buildings, a DOE goal for the RSF project is to help change the way commercial office buildings are designed and built in the United States. NREL researchers are monitoring and documenting the energy performance of the RSF and sharing those results with industry to show how achievable ultra-energy-efficient buildings are today.
The RSF is the second facility at NREL to achieve LEED Platinum. In 2007, NREL’s Science and Technology Facility was the first federal facility in the nation to be certified LEED Platinum.
“NREL is proving how our research on energy efficiency, commercial building technology, and renewable energy can be translated to today's commercial properties at a cost-competitive rate,” said NREL Deputy Lab Director Bill Glover.
The project’s RFP specified LEED Platinum as a requirement, not a goal, and it has become the largest net-zero energy building in the nation.
“The RFP had a lot of interesting, peculiar and innovative requirements that captured our team’s imagination,” says Tom Hootman, director of sustainability for Denver’s RNL, the project architect and one-third of the design-build team.
General contractor Haselden Construction of Centennial, Colo., formed a team with RNL and the San Francisco office of mechanical-systems designer Stantec. They entered a design competition for the $64-million RSF, which they built by carefully balancing cost savings and green elements to create a prototype for the future.
Completed in June 2010, the RSF is designed to hold more than 800 Dept. of Energy and NREL administrative staff and will serve as a living laboratory, calculating all of the building’s energy needs and use while capturing everything from light levels to electrical and water usage on TV screens in the building’s lobby.
Stantec has been designing low-energy and zero-energy buildings and LEED-Platinum facilities throughout the country, honing those concepts on projects of a much smaller scale, says John Andary of Stantec. He says the biggest challenge of the RSF project was its size. Stantec’s largest LEED-Platinum project before this was a 40,000-sq-ft building in the San Francisco Bay area.
“The trick was how to scale that up to 222,000 sq ft,” Andary says.
At almost twice the size of the next largest structure on the 18-building Colorado campus, the RSF comprises 60% of the site’s total square footage, says Greg Collette, DOE project officer, who is directly responsible for the planning, design and construction of the RSF. He’s also managing build-out of the NREL campus.
“One thing we asked for in our RFP was an iconic facility,” Collette says. “We didn’t want anything ostentatious, but we wanted the presence to be easily recognizable.”
The result is an H-shaped building that tells a story about energy. But RNL’s Hootman says the most interesting thing about the project is that a lot of the energy strategies are tied to architecture rather than building systems. “Of course, there is an efficient mechanical system, but passive strategies were the key,” he says.
Daylighting was one of the most critical elements of the building’s sustainable design, and the building’s long, narrow wings running east to west maximize north-south exposures. Other passive strategies—thermal mass with a thermal labyrinth; transpired solar collectors; natural ventilation; night purging; and design of the workplaces, finishes, windows and walls—were all important in getting to zero energy.
Occupants will spend much of their time in the two long wings of the building, which will stay cool most of the time due to its thermal mass, much like a European cathedral or a cave, says Jerry Blocher, Haselden senior project manager.
The building’s unusual exterior skin system is precast, insulated “sandwich” panels made of recycled materials that form a concrete layer, insulation layer and concrete layer. There is no drywall finish on the inside. Instead, the concrete is painted and left exposed to interact with the space and take advantage of the thermal mass. Craned on site, this modular construction system was not labor intensive and offers a cost advantage.
The team also worked not to overglaze the building. Extensive modeling was conducted to get the windows sized just right to achieve the desired amount of daylighting while keeping the high cost of glass in mind, Hootman says. The building’s main wings have a 25% window-to-wall ratio.
Temperature sensors alert motorized windows to open at night, bringing Colorado’s coveted cooler evening air into the building during the summer. Sensors also keep lights turned off when not needed during the day.
LightLouver devices bounce light from the south side of the building onto a structure overhead, creating a much more robustly daylit space and reducing the building’s cooling needs. Andary calls it a holistic creation of engineering/construction/architecture working together.
The building is intended to have enough thermal mass so that once it gets to a certain temperature, it can maintain that temperature. Meeting rooms and a lobby are located in the center bar of the H with a more traditional heating/cooling system. An extremely efficient radiant cooling system can run cool or hot water through tubing located in the floors, depending on what’s needed.
Transpired solar collectors (a technology originally designed by NREL) are placed in strategic locations on the RSF’s south façade to draw warm air into the building’s labyrinth. A low basement located 5 ft under the south wing has concrete walls that are staggered to make the heat of the day or the cool of the night take S-turns through the space and linger awhile, losing its cool or — depending on the season — its heat, and then slowly releasing the thermal energy to help cool or warm the building.
Early in the design process, the team looked at what kind of recycled materials would be easily usable, easily found and could be acquired locally.
“A theme throughout the design and construction was the simplicity of how we achieved our energy goals,” Blocher says. “All of our sustainable technologies were at reasonable price points and the result of thinking harder about how to do it right rather than the result of spending a lot of money.”
Recycled local material is featured in the main entry, where Colorado beetle-kill pine offers a warm, architectural accent. The project’s concrete is recycled aggregate from the old runways of Denver’s Stapleton Airport.
A week before the project’s steel was needed, Haselden located recycled natural gas pipe to serve as the building’s structural columns. This rare architectural feature is coated with a clear, environmentally sensitive finish typically used inside ships to coat ballast tanks.
And in the ultimate use of local and regional materials, gabion rock walls were constructed around the building’s exterior using stone sifted from the dirt Haselden excavated for the foundation. Taking care to avoid rattlesnakes, crews sifted the stones, moved them 100 yd and hand-placed each one in a basket for a collaborative design-build effect.
Haselden’s original contract for the government-funded project included only what was needed to construct the building and anything 5 ft around it. The contract didn’t include an access road, basement, storm-sewer work, fire or other systems, Blocher says.
The contractor signed a contract for critical infrastructure work—jobsite trailers, digging trenches and so forth—and a change order to build an access road months after breaking ground on the building.
As a result, the construction crew spent the rainy month of May pouring concrete for foundations when they were not yet under contract to do any storm-sewer work. “Rain would fill up a hole, and we had no place to send it because we were not under contract to build a storm sewer yet,” Blocher says.
Haselden worked to keep the 18-month schedule and the 400-person crew at its peak on track, but in October 2009, just six months before the project was to be complete, NREL decided to reprogram the building’s modular furniture configuration, which was designed to help with ventilation, daylighting and other passive strategies.
Blocher says the change was about more than just rearranging furniture; it affected the building’s heating/cooling and required opening up shafts as well as redoing under-floor layouts with electrical and data distribution ductwork underneath.
“It was a tremendous challenge,” Blocher says, noting that Haselden never fully recovered its flow, although the project was completed a day early.
“This design-build team came together to propose on this facility based just on our RFP,” says the DOE’s Collette. “They came up early on with the idea that it had to be looked at from an energy perspective first. Typically, architects drive the look of a facility and then bring in engineers to make it work. That wasn’t the case here. Integrating the energy profile of the facility into the design and construction saved them a lot of construction dollars.”
Andary adds: “When you have an owner like NREL that is really focused on performance in a building, it’s amazing what you can achieve with your construction/design professionals. When owners are wishy-washy with what they want, the design tends to degrade unless there is a strong architect who can drive the agenda. There’s nothing like having an owner say, ‘I want this,’ and having the team rise to the occasion.”
Project Team
Owner: U.S. Dept. of Energy’s National Renewable Energy Laboratory, Golden, Colo.
Architect: RNL, Denver
MEP Engineer: Stantec, San Francisco
Civil Engineer: Martin / Martin, Lakewood, Colo.
Structural Engineer: KL & A, Denver
Design-Build Contractor: Haselden Construction, Centennial, Colo.
Among the Subcontractors: Trautman & Shreve (mechanical), Denver; Weifield Group (electrical), Denver; Rocky Mountain Prestress (precast concrete), Denver; JR Butler (glazing), Denver; OfficeScapes (modular furniture), Denver; Paxton & Vierling Steel (steel fabricator), Carter Lake, Iowa; Architectural Energy Corp. (LEED, daylighting and commissioning consultant), Boulder, Colo.; Technology Plus (IT and AV consultant), Aurora, Colo.
