Advanced lighting control systems (ALCS) provide networked control and monitoring capabilities of connected luminaires via onboard metering and system reporting features. These advanced features allow system owners to dynamically balance visual comfort and lighting energy use. CLTC, in collaboration with SDG&E, developed a technology validation program to determine the accuracy and reliability of onboard metering and system reporting features of advanced lighting control systems. Project outcomes are intended to assist SDG&E and other utilities with future incentive program development activities focused on this product category.
The project team applied the procedure to three commercially available ALCS in order to refine the methods and help the utility determine if such features were currently reliable and accurate enough to substitute for the independent and expensive collection of sub-metered data often required to calculate project savings and associated financial rebates.
The project team conducted a market assessment, defined a system testing methodology, and tested three commercially available advanced lighting control systems in accordance with the methodology to validate its procedures and identify areas in need of refinement. The three systems are:
- “ALCS 1” employs "real power" methods to measure both the current and voltage.
- “ALCS 2” employs "apparent power" methods which determines energy use by multiplying the measured root-mean squared (RMS) current by the assumed RMS voltage.
- “ALCS 3” employs "real power" methods to measure both the current and voltage.
Modeled power measurement sampling rates were also evaluated to determine their effect on reported energy use. Simulated shorter sampling rates resulted in more accurate energy use. Five-minute time delays on the simulated occupancy sensor combined with one minute sampling rates resulted in the most accurate energy use reported by the modeled ALCS system. To ensure accuracies within 1% of reference analyzer energy use for the occupancy pattern used in the simulation, the sampling of ALCS power measurement must occur more frequently than once per minute. An alternative approach to ensure sufficient sampling over time is on-demand sampling, where power measurement occurs at light level changes.
For utilities interested in using ALCS systems to provide lighting energy use data for measured incentives, it is important to note the differences in power measurement and reporting capabilities of ALCS available today. Test results demonstrate the importance of accuracy in power measurement and frequency in sampling and sub-sampling rates. Each ALCS manufacturer measures and reports energy differently and each system has varying degrees of accuracy. If ALCS incorporate revenue-grade meters and improve the accuracy of sub-sampling and reporting capabilities, ALCS will increase their appropriateness for use as part of a measured incentive utility program.
Principal Investigator: Konstantinos Papamichael