Direct Current as an Integrating and Enabling Platform
The energy savings and interoperability advantages of DC systems can be significant for ZNE buildings.
Lawrence Berkeley National Laboratory
Recipient
Berkeley, CA
Recipient Location
9th
Senate District
14th
Assembly District
$1,000,000
Amount Spent
Completed
Project Status
Project Result
The project is complete. Results indicate that no technology breakthroughs are needed to make DC power distribution a viable option for zero net energy buildings. There are, however, many barriers to the adoption of DC power, with product availability and cost as the most significant ones. There also is a general unfamiliarity with DC power in the building community, from designers to code officials, contractors, tradespeople, maintenance staff, building owners, occupants, and policy makers. The recipient indicates that there is a real need for DC power market development in the form of product standards, building and fire codes that explicitly account for DC systems, DC specific design practices, improved trade familiarity, and a wider variety of DC ready products in a range of product categories, feature sets and capacities. The final report will be published in January 2019.
The Issue
Despite the potentially significant benefits of direct current (DC) and alternating (AC)-DC hybrid building systems over traditional AC-powered electric systems, DC and AC-DC buildings face a number of technical and institutional barriers to their adoption. Policymakers and building developers who wish to explore opportunities and pathways to incorporate DC and AC-DC hybrid systems, lack independent baseline information and tools to inform their policy-making, designs and deployment decisions. As a result, they are hesitant to move forward on promoting and implementing the early adoption of DC and AC-DC hybrid systems.
Project Innovation
This project evaluates DC and AC-DC hybrid applications to determine market segments where projects are technically and economically feasible. The research covers existing and new buildings. For the market segments identified, the Team is developing and piloting tools to help building developers incorporate these systems into their building designs. The tools include DC and AC-DC hybrid design guidelines, and design templates.
Project Benefits
The potential energy savings and interoperability advantages of DC and AC-DC hybrid systems are estimated to be significant, especially for zero net energy (ZNE) buildings that integrate on-site renewable energy with battery storage and electric vehicle (EV) charging. Prior research estimates energy savings potential of 10% to 30% for DC-powered ZNE buildings that incorporate storage and or EV charging. This project will help accelerate the adoption of DC and AC-DC hybrid applications by compiling existing knowledge, identifying standards and technology gaps, designing tools and identifying a path forward to help ensure successful outcomes for DC and AC-DC hybrid applications in key market segments from which these systems can scale.

Affordability
Use of DC power will avoid unnecessary power conversions, improving efficiency, and eliminating the need for some conversion equipment. Total energy savings are estimated to be $800 million over a ten-year period, assuming full penetration of DC distribution in all buildings that install PV between 2015 and 2024.

Environmental Sustainability
Reduction in energy use could result in reductions in greenhouse gas emissions. Also, eliminating the need for some conversion equipment could reduce the cost of PV, storage and other related systems.

Reliability
DC power has a long history of reliability in the telecommunications sector. Similar improvement is expected for DC power use in buildings. DC power use in buildings will improve reliability by eliminating failure in power conversion equipment.
Key Project Members

Richard Brown
Subrecipients

Electric Power Research Institute, Inc.

The Regents of the University of California (CIEE)

Arup North America Ltd

Pacific Northwest National Laboratory

Match Partners

EMerge Alliance

California LMCC IBEW-NECA
