Dual-Loop Photosensor Control System for Daylight Harvesting

Dual-Loop Photosensor Control System for Daylight Harvesting
Abstract: 

Photosensor control systems have been available for more than two decades, but they have struggled to gain widespread use due to issues with reliability. To address these issues, CLTC partnered with WattStopper, Walmart, Sacramento Municipal Utility District, Southern California Edison, and San Diego Gas & Electric Company to develop a more reliable, more effective daylighting control system capable of sensing changes in daylight levels with increased accuracy and responding with more appropriate adjustments in electric light levels. Applications for this technology include commercial spaces with skylights, such as warehouses and retail stores.

The dual-loop photosensor control system for daylight harvesting solves shortcomings of open-loop and closed-loop daylight harvesting approaches by combining the two technologies into one. It 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. The open-loop system informs operation of electric lighting when occupant interference affects the closed-loop control sensor.

The system is self-commissioning and updates every night to adapt to changes in the interior space, such as occur when retail displays are altered, inventory color changes, or furniture is rearranged, etc.

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. In late 2012 WattStopper began manufacturing the LMLS-600 photosensor control device, based on the RD&D activities described here.

Principal Investigator: Konstantinos Papamichael

Staff Contact

Konstantinos Papamichael, Ph.D.

Professor Emeritus, Department of Design