University of California, San Diego
IN-4: Innovation 4

The UC San Diego Sustainability Resource Center (SRC) is a living laboratory that houses an innovative DC-DC lighting system. Initially proposed by students to provide a meeting and brainstorming location for students, faculty, and staff, it is a welcoming and spacious work, collaboration, and meeting place showcasing campus sustainability efforts and a model environment featuring sustainable design. One example of the sustainable design that contributed to the LEED Gold certification includes the first in the nation DC-DC lighting system that utilizes solar power.

Partnering with the EMerge Alliance industry association, UC San Diego installed a unique direct current to direct current, or DC-DC, lighting system in November of 2009. Historically, native DC power generators required their power to be converted to AC for local distribution, reducing their efficiency and increasing costs. Using native DC power generated from on-site solar panels to drive DC loads directly improves building efficiency, reduces energy costs, and reduces environmental footprints.

The center’s one-of-a-kind DC-DC lighting system is both innovative and extremely efficient. The EMerge Alliance standard delivers a flexible platform that allows the SRC to readily adapt to changing lighting needs.

The SRC system uses four photovoltaic solar panels that convert sunlight into clean, renewable direct current power (DC). Energy is saved by not converting the power into alternating current, or AC. Instead, DC power is converted to low-voltage, Class 2 power, for efficient distribution at the room level, eliminating the inefficiency of successive AC to DC power conversions at the device level. Each of these conversions usually cause a 10% loss in energy. DC energy travels to state-of-the-art DC power components, further increasing efficiency and avoiding the 5%-15% total energy loss associated with a conventional lighting system.

An innovative ceiling infrastructure uses safe, low-voltage DC power to energize flexible “plug and play” lighting fixtures that can be moved by occupants as needed. Solid-state, DC-based LED lighting further maximizes energy efficiencies and lighting longevity, due to the absence of heated filaments. The following graphic illustrates this system.

Several details within the center also demonstrate a commitment to energy efficiency. The DC-driven Wattstopper energy-efficient sensors and controls use both light-level and motion sensors to reduce the need for artificial lighting. Once programmed, the LED task lighting can also turn off automatically upon leaving the office. Active Safety photoluminescent (glow-in-the-dark) exit signs are non-electrical, non-radioactive, made from recycled aluminum, and completely recyclable.

The combination of maximizing natural lighting and using DC solar-generated power, along with distributing it as DC directly to highly efficient lighting equipment, define the SRC’s unique lighting design. This installation also provides students with the opportunity to research DC-DC grid technology for its configuration efficiencies, and outreach programs through the center enable students to further pursue their sustainability-related interests.

When the solar panels aren’t generating energy, the SRC draws from the energy-efficient campus grid. The majority of lighting needs are supplied by clean renewable energy.

In an effort to influence sustainable practices in our community and ensure a more sustainable future, the SRC strives to provide an environment where organizations can collaborate and communities can learn about sustainable solutions by seeing them in use.