It's an old idea that is getting new currency: The use of safe direct current (DC) power is finding a home in commercial and institutional buildings. DC power offers buildings numerous benefits, from energy savings to design and space flexibility to easier incorporation of renewable energy sources.
Leading the charge for DC power is the EMerge Alliance. The Alliance is working to facilitate the hybrid use of AC and DC power, says Brian Patterson, chairman of the EMerge Alliance and general manager of Armstrong World Industries' building products division. Alliance standards integrate interior infrastructures, power, controls, and devices in new construction or renovation applications as well as in a common microgrid platform.
Why DC power? One reason is the growing number of electronic devices. Those devices operate using DC power, but the building power distribution system feeds them AC power, which must be converted to DC. Those conversions waste energy. Another reason to use DC power is that renewable energy sources such as photovoltaics produce DC power that is converted to AC to be used within the building. Once again, the conversions waste energy.
The Alliance sees increasing use of DC microgrids within buildings. A microgrid is an electricity distribution system containing loads and distributed energy resources (such as distributed generators, fuel cells, renewables, energy storage devices, and/or controllable loads) that can be operated in a controlled, coordinated way either while connected to or disconnected from the main power network. Considered by many experts to represent the ideal building blocks of a far more resilient and efficient Smart Grid, DC microgrids "offer the local ability to couple multiple sources of power without complex frequency synchronization and can better match the native DC power sources with their predominantly native DC loads, thus minimizing conversion complexity and efficiency losses," Patterson says. As a result, microgrids behave more robustly in the face of blackouts and natural disasters, terrorist attacks or human errors.
The EMerge Alliance's charter covers development of standards within five building space categories: occupied space, data and telecom space, building services, outdoor and whole campus/building microgrids.
"Each of these areas has unique characteristics, which their respective application standards take into account," Patterson says. "As such, the use of DC power in each area can be implemented separately, in both new and existing buildings, in an opportunistic way over time."
Much of EMerge's efforts have revolved around the development of standards, the first of which, released in 2009, addressed 24-volt DC power in occupied workspaces. "Applications (of that standard) include open and private office space, conference facilities, community centers, education classrooms, and retail space," Patterson says.
The first EMerge standard has been positively received. "There are more than 20 pilot and production installations spread out across the country already," Patterson says, "We think that's pretty encouraging for a mature industry that's been historically slow to adopt new technologies."
Included in the 24-volt DC power installations scheduled this year are a "living lab" solar-powered DC classroom on the Berks Campus of Penn State University, and the addition of roof-top solar to the sixth floor DC-powered conference facilities at U.S. Green Building Council headquarters in Washington, DC.
"The EMerge Alliance is an open industry association currently developing standards leading to the rapid adoption of DC power distribution in commercial buildings," says Brian Patterson, chairman of the EMerge Alliance and general manager of Armstrong World Industries' building products division. "Formed in 2008, the Alliance's vision is to develop and deploy a family of DC power distribution standards to create microgrids which meet the evolving needs of commercial buildings."
Currently comprised of more than 100 organizations, the Alliance's membership ranges from building products manufacturers in such areas as ceilings, lighting, HVAC and controls to architectural firms, government agencies and trade associations. Building professionals can also help by getting directly involved in the EMerge Alliance itself as an observer/supporter or as a leader or governing member.
For more information about the Emerge Alliance, contact 925-275-6617 or visit www.EMergeAlliance.org.
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