The electrical grid in the United States – including generation, transmission, and distribution – is based on alternating current (AC). However, an increasing number of devices required by modern life (e.g. computers, mobile devices, and LED lights) run on direct current (DC), requiring that the power be converted before it can be used. As it currently stands, the conversion process is inefficient, accounting for energy waste of up to 20%. Oddly enough, there’s even more potential for energy waste with the implementation of onsite DC power generation, such as solar panels and batteries. The power is almost always converted back to AC before it gets to the building’s system, and then converted back to DC for use by devices in the facility.
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The answer to this inefficiency problem seems pretty straightforward, though converting an existing facility or designing a new building around DC power systems will have a high up-front cost. To help focus attention to the matter and get more folks on board, the U.S. Green Building Council (USGBC) has announced a new pilot credit to help spur facility designers and managers to find greater energy cost savings by cutting out the need for power conversion entirely.
To further generate interest, the USGBC is offering two options for the program. The first option is a solid choice for facility managers looking to start down the path to increasing energy efficiency. It requires that “95% of the load of at least one major energy system [in the facility] to operate directly off DC power.” This way, facility managers can more easily prioritize and budget for these projects, addressing them as needed.
The second option is much broader, and “is a performance-based approach [offering] a whole-building energy simulation alternative compliance path, rewarding more points for more energy saved in designs that integrate DC power.” Clearly, if you’re able to incorporate DC power into a building design or redesign at the outset, you’ll generate larger savings over the long run. But going all-in on a DC power system will require a much larger outlay of capital than that required by the first option.
The USGBC hopes that by offering credits for switching to or integrating a DC power system into their building design will also incentivize manufacturers to produce more of these systems, which in the future will help drive some of the cost down. Given that DC powered devices are becoming more ubiquitous, and are more energy efficient than their AC counterparts, switching to a DC system seems like a good way to get ahead of the curve. Also, think of the labor costs you’ll save by not having to send someone to Tosche Station for power converters.