According to a new report from the U.S. Green Building Council (USGBC), while power generation, transmission and distribution in the United States tend to be predominantly alternating current (AC), an increasing number of devices in buildings use direct-current (DC) power, meaning AC power entering these buildings must be converted to DC before DC-compatible devices can use it.
The report notes the inefficiencies in the conversion process result in energy waste of between 5–20 percent. Furthering the problem is that, even with the parallel rise of DC power sources in buildings, this DC power is almost always converted back to AC power before running through a building's electrical system, where it is then converted back to DC for use by the DC-compatible devices.
According to the report, an effective way to reduce this consistent energy waste would be to require building designers and developers to integrate DC power systems into their buildings. To help move this concept forward, the USGBC has created a new pilot program: Direct Current Power Systems.
"The new LEED pilot credit is designed to break the chicken-and-egg dilemma related to DC power in buildings," the report states. "Manufacturers are not inclined to produce DC-powered systems, because they aren't specified in design plans. On the other hand, design teams don't specify them, because manufacturers don't produce them. This new incentive for building designers to integrate DC power into buildings will help spur interest in the specification of DC systems, and thereby their production by manufacturers."
Building project teams will have two options to earn up to 18 LEED points for integrating systems or subsystems into their design that operate directly on DC power.
Option No. 1 is a prescriptive approach that will require 95 percent of the load of at least one major energy system to operate directly off DC power. Qualifying systems will include: elevators, escalators, indoor LED lighting, outdoor LED lighting, EV charging, heating-cooling-ventilation, fans, plug loads, information technology and process loads.
Option No. 2 is a performance-based approach that will offer a whole-building energy simulation alternative compliance path, awarding more points for more energy saved in designs that integrate DC power.