In the late 19th Century, the so called ‘war of the currents’ waged between DC entrepreneur Thomas Edison and AC inventor Nikola Tesla. Although Tesla’s revolutionary AC technology won the immediate battle, some 120 years later, it looks like Edison might actually be winning the war after all…
In this article, Lighting Designer Brad Koerner discusses the forthcoming revolution of DC electrical infrastructure for commercial and residential buildings.
Do you know why you must lug around all those chargers for your smartphones, tablets and laptops? Why every “smart” device in your home or office requires some big, obnoxious power brick? Why the solar panels on your roof require some giant inverter box in your garage?
It’s because every digital device in our modern world runs on DC (direct-current) electricity, while our ancient utility grids and the wiring infrastructure in our buildings remain stuck using AC (alternating-current).
Every time you plug a power converter into those ancient AC-outlets, you are wasting electricity. Ever notice how hot those power converters get? That is your electricity, money and planet being squandered as waste heat.
Almost every device in a modern building or home uses DC, including LED lighting, sensors, computers, IT networking and even modern mechanical systems. Literally thousands of devices in even a modest sized commercial or multi-unit residential building require these wasteful power converters.
And to compound this huge disconnect between our AC electrical grids and our DC building infrastructures, we are now adding huge quantities of DC-generating solar panels and DC-based battery storage to make our buildings net-zero energy consumers.
The cost of onsite solar PV generation has dropped to the point of grid parity – or cheaper – meaning that in many cases it is cheaper for a building owner to generate their own DC power rather than to buy AC power from a utility company. And the cost of onsite battery storage continues to drop, bridging the gap between the peaks and troughs of generation and consumption.
Here is the shocking number: Researchers estimate that commercial buildings save 15% of their total power by skipping all the wasteful DC-AC-DC conversions. Why is 15% such a big deal? Because it is estimated that commercial and residential buildings consume 40% of the total energy used in the United States alone.
Modern buildings going forward may only need extra power from the grid for short periods of the year, such as during the coldest, darkest part of the winter in Northern climates. The rest of the year, buildings will run almost entirely on internal flows of DC power. We are at the inflection point of a new revolution: DC-power “nanogrids” are set to replace the AC-infrastructure in many, if not most, commercial buildings, resulting in massive energy savings while reducing hardware and providing advanced digital control of power.
Recently there have been some notable pilot projects completed based on central DC-infrastructure. Let’s look at examples from 4 manufacturers across the U.S. and Europe:
Ferroamp is a Stockholm-based startup that has completed several large projects, most notably the Akademiska Hus in Gothenburg which is claimed to be the largest DC-powered office building. The project has some impressive specs, including 200kWh DC connected battery storage, 140 KWpk PV panels, 100kW DC fans, and over 1,500 light fixtures equaling 12kW of DC.
DC Systems is an Amsterdam-based startup that has completed a couple notable large scale projects with DC nanogrids, including the sustainable circular-economy CIRCL office-pavilion for Dutch bank ABN AMRO and the Pulse academic building at the Technical University of Delft.
Nextek Power Systems is a Detroit-based startup that is supplying a large DC system for a 62,000 sqft NZEB office building in Washington, DC for AGU, the scientific non-profit research group. Nextek was a key contributor to the earlier EMERGE Alliance DC specification.
LumaNEXT is a Pittsburgh-based startup that has rolled out LED lighting retrofits with centralized DC power conversion in over 1,000 Rent-A-Center retail locations. Are DC-systems only for fancy-pants flagship projects with all sorts of green subsidies and other nonsense? Absolutely not. RAC stores are extremely cost conscious, yet DC power provided real savings. LumaNEXT is currently piloting DC-power projects with several other major retail discount chains.
These early pilot projects show tremendous promise for the DC power revolution. To throw fuel on the fire, the U.S. Green Building Council just added substantial bonus points for including DC power systems in its LEED green building certification program.
With DC power, we can reduce power waste substantially, reduce electronic hardware and the associated maintenance & e-waste issues, and open the door to advanced energy management in buildings. More and more end-devices in construction projects are switching to DC power, such as the growing trend for track lighting that uses 48 vDC. And advanced DC-based technologies like solid-state switching and solid-state fault interruption promise to channel, manage and measure power with more precision than ever before.
As we move towards greater numbers of net-zero energy buildings and demand more localised energy resiliency in ever more turbulent times, a most interesting revolution is poised to transform our electrical infrastructure.
About the author
Brad Koerner is a creative leader in the application of advanced technologies in architectural systems. Brad recently founded Koerner Design in Amsterdam and has been supporting several early-stage tech ventures in the building industry.
Brad previously spent 20+ years in the architectural lighting industry, where he developed award-winning architectural lighting projects as well as industry-leading LED lighting and control technologies.
Brad is an accomplished speaker and writer forecasting future trends in architectural systems. He has presented at over 30 professional conferences globally and his work has been published in numerous popular & trade publications and through his lighting blog Lucept.
Brad received his M.Arch degree from Harvard University and his B.S. in Architecture from the University of Virginia.