Net zero buildings – which consume so little power that they takenothing from the grid– have been the holy grail of energy efficiencyexperts for years.
Now the Department of Energy’s National Renewable Energy Laboratory(NREL) has taken on the challenge of designing and constructing one ofthe world’s most energy-efficient, net zero buildings – the NREL’s ownnew Research Support Facility (RSF). The NREL’s architects and engineers have spent hundreds of hoursshaving every little bit of energy consumption from the $64 million,219,000 square foot building. Now, midway through construction, theresearchers are still making little adjustments to their calculationsand the design. It is scheduled to open mid-2010.
The RSF’s original specification documents stipulate 25 kBtu persquare foot per year. How little energy is that? By comparison,conventional office buildings built over the past 30 years typicallyuse three times more energy – an average of 90 kBtu per square foot peryear. That’s like taking a 1980s-era family sedan and demanding that itget 60 mpg.
The energy requirements are aggressive even by new constructionstandards. The NREL’s requirement is 50% more energy efficient than thenew 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 bebuilt to LEED Platinum status, the highest designation by the U.S. Green Building Council.
"Our energy simulations told us that buildings can perform a lotbetter," NREL Principal Group Manager Paul Torcellini said. "NREL needsto lead the industry. We’ve maximized our impact by integrating today’stechnologies to build a zero-energy office building."
The energy efficiency number was not chosen arbitrarily. Researchers from NREL’s Buildings Research and Development programperformed computer simulations and collected data from high-performingbuildings nationwide to create an energy specification that could bemet within the project’s budget, yet set an ambitious new energyefficiency benchmark for the nation.
"We set the energy efficiency requirement and everything in the RSFhas cascaded from that number," said Ron Judkoff, manager of NREL’sBuildings Research program. "It required all of the players in theproject to commit to real energy efficiency. When you are trying to gothat low, an integrated design approach is needed."
The RSF is a "design-build" project in which the team will deliverthe advanced building for a market-competitive price of about $280 persquare foot. The building is under construction at NREL’s South TableMountain Campus near Golden, Colo.
Since RSF construction began last spring, the Laboratory’srequirements grew. Because of its modular design that eschewsstructural columns, the interior has been creatively rearranged toaccommodate nearly 100 additional staff. But more people require moreenergy, and so the energy use requirement for the office space has beennudged 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 wingsconnected by an enclosed bridge and courtyards. To allow daylight topenetrate the work spaces, NREL recommended that the office wings be nowider 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 overhangingshades 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, evaporativecooling, 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 DataCenter, which requires enormous energy. The features reduce thecenter’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.