EMerge Details DC-Power Standard at Green Building Power Forum

June 04, 2009 by Jeff Shepard

While there were extended discussions about long-term development of completely dc-powered buildings at Darnell’s Green Building Power Forum (GBPF), the recently-formed EMerge Alliance is moving aggressively forward to finalize dc-power distribution standards to be implemented in commercial products before the end of 2009. In fact, the first EMerge-proposed standard document is scheduled to be released to full members by the beginning of July.

Bypassing the difficulties inherent in developing completely dc-powered buildings, EMerge has proposed a hybrid architecture that retains the typical 120-277 Vac branch circuits found in buildings and overlays an additional dc-powered "embedded" bus to provide local power to devices such as lighting fixtures. Several EMerge members were represented at GBPF including, Armstrong World Industries, Delta Power Products, Green Plug, Houston Advanced Research, Kanepi Innovations, Nextek Power Systems, Osram Sylvania, Southern California Edison, and Tyco Electronics.

As described by Ben Hartman, Chairman of the EMerge Alliance Technical Committee, the final standard is expected to cover three general areas; power, infrastructure and peripherals. The power block includes ac-dc power supply modules (PSMs) with one or more isolated 24Vdc outputs limited to a maximum of 100VA (Class II safety) with overload and over-voltage protection and auto restore upon removal of the fault condition. Each of the 100VA channels is called a "power pixel."

The power source is expected to provide power density of 2-4W per square foot of floor space in the powered area. Infrastructure includes a variety of components including structured cabling, powered bus bar components (such as ceiling tiles), special connectors and so on. Peripherals include the powered devices such as lights, sensors, motors, HVAC, and so on.

Product registration and interoperability testing will be performed at the California Lighting Technology Center at the University of California’s Institute for Energy and the Environment. Upon passing the performance and interoperability testing, products will be awarded the EMerge product logo. A few companies revealed examples of EMerge-compliant products.

For example, Brian Patterson, Chairman of the Alliance and General Manager for Business Development at Armstrong World Industries, demonstrated the "DC FlexZone™" line of powered ceiling tile grid frames based on the proposed EMerge standard. The system would be installed mechanically by acoustical contractors, just like standard suspension systems, with unpowered cross tees and accessories. An electrical contractor would follow up by installing the ac-dc power supplies and energizing the low-voltage grid in the ceiling.

Osram Sylvania presented its dc-powered lighting technologies that are targeted at EMerge-compliant applications. Kanepi Innovations described wireless controls in plug and play low-voltage dc-powered infrastructures such as EMerge environments. And Nextek Power Systems presented a higher-level look at power distribution and power management for dc power networks in buildings.