Photosensor control systems, which have been available for more than two decades, have struggled to gain popularity because they often are unreliable. This project is a partnership between CLTC, WattStopper, Walmart, Sacramento Municipal Utility District, Southern California Edison, and San Diego Gas & Electric Company to develop a daylighting control system with increased reliability to sense daylight variations in the controlled space.

Dual-loop testing space at CLTC		Big-box stores provide an ideal application for the system		Dual-loop system installed at Walmart

The goal of this project is to increase the reliability and effectiveness of daylighting control systems by improving their daylight-sensing capabilities in a cost-effective way

• Commercial spaces with skylights
  

1. Employs a closed-loop control photosensor and references an open-loop photosensor to determine if changes to the closed-loop signal are from daylight or space changes.
2. Uses information from the open-loop system to operate the electric lighting when occupant interference affects the closed-loop control sensor.
3. Self-commissioning system determines the closed-loop set point and dimming curve by measuring the electric light levels in the space. The system updates every night to adapt to permanent space changes.

LICENSING:
Four different co-exclusive license agreements were made between UC Davis and Philips Lighting, WattStopper, Axis Technologies Inc., and Convergence Wireless Inc. to commercialize inventions that reduce the cost and increase the reliability of daylight harvesting systems. The license agreements cover a package of patents and patent applications describing strategies and technologies developed by CLTC.