DOE's NREL Builds One of the World’s Most Efficient Buildings

Net zero buildings – which consume so little power that they take nothing from the grid– have been the holy grail of energy efficiency experts for years.

Now the Department of Energy’s National Renewable Energy Laboratory (NREL) has taken on the challenge of designing and constructing one of the world’s most energy-efficient, net zero buildings – the NREL’s own new Research Support Facility (RSF).

The NREL’s architects and engineers have spent hundreds of hours shaving every little bit of energy consumption from the $64 million, 219,000 square foot building. Now, midway through construction, the researchers are still making little adjustments to their calculations and the design. It is scheduled to open mid-2010.

The RSF’s original specification documents stipulate 25 kBtu per square foot per year. How little energy is that? By comparison, conventional office buildings built over the past 30 years typically use three times more energy – an average of 90 kBtu per square foot per year. That's like taking a 1980s-era family sedan and demanding that it get 60 mpg.

The energy requirements are aggressive even by new construction standards. The NREL’s requirement is 50% more energy efficient than the new commercial energy code issued by the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE). It is also over and above the additional requirement that the RSF be built to LEED Platinum status, the highest designation by the U.S. Green Building Council.

"Our energy simulations told us that buildings can perform a lot better," NREL Principal Group Manager Paul Torcellini said. "NREL needs to lead the industry. We've maximized our impact by integrating today's technologies to build a zero-energy office building."

The energy efficiency number was not chosen arbitrarily. Researchers from NREL's Buildings Research and Development program performed computer simulations and collected data from high-performing buildings nationwide to create an energy specification that could be met within the project's budget, yet set an ambitious new energy efficiency benchmark for the nation.

"We set the energy efficiency requirement and everything in the RSF has cascaded from that number," said Ron Judkoff, manager of NREL's Buildings Research program. "It required all of the players in the project to commit to real energy efficiency. When you are trying to go that low, an integrated design approach is needed."

The RSF is a "design-build" project in which the team will deliver the advanced building for a market-competitive price of about $280 per square foot. The building is under construction at NREL's South Table Mountain Campus near Golden, Colo.

Since RSF construction began last spring, the Laboratory’s requirements grew. Because of its modular design that eschews structural columns, the interior has been creatively rearranged to accommodate nearly 100 additional staff. But more people require more energy, and so the energy use requirement for the office space has been nudged to a still amazing 31.75 kBtu/sf/year.

The RSF building is designed with a number of innovative energy-saving features, including:

• A "lazy H" configuration of two narrow multi-story office wings connected by an enclosed bridge and courtyards. To allow daylight to penetrate the work spaces, NREL recommended that the office wings be no wider than 60 feet across rather than a typical 120 feet.
• A subterranean air handling network or “thermal labyrinth” will mimic a cave to naturally heat and cool the building.
• Triple-glazed windows individually fitted with exterior overhanging shades and side-fins to reduce interior heat gain, heat loss and glare, while allowing for daylighting.
• Light-reflecting devices that push the daylight deeper into the office spaces.
• A dynamic network of automatically controlled windows, evaporative cooling, radiant heating and cooling, window glazing and heat recovery.
• Insulated precast concrete walls for passive climate control, including transpired solar collectors for heating.
• A combination of evaporative cooling, outside air ventilation, waste heat capture and more efficient servers in the building’s Data Center, which requires enormous energy. The features reduce the center's energy use by 50 percent over traditional approaches.
• Using internet-tied telephones rather than standard models.
• Favoring laptop computers over PC workstations.
• More energy-efficient elevators including energy recapture.
• Highly reflective interior paint and workstations in neutral hues to enhance daylighting.
• Low workstation walls to encourage daylighting and natural airflow.