Francis Rubinstein

Improving the Performance of Photo-Electrically Controlled Lighting Systems

The ability of a photo-electrically controlled lighting system to maintain a constant total light level on a task surface by responding to changing daylight levels is affected by the control algorithm used to relate the photosensor signal to the supplied electric light level and by the placement and geometry of the photosensor. We describe the major components of a typical control system, discuss the operation of three different control algorithms, and derive expressions for each algorithm that express the total illuminance at the task as a function of the control photosensor signal. Using a specially-designed scale model, we measured the relationship between the signal generated by various ceiling-mounted control photosensors and workplane illuminance for two room geometries under real sky conditions. The measured data were used to determine the performance of systems obeying the three control algorithms under varying daylight conditions. Control systems employing the commonly-used integral reset algorithm supplied less electric light than required, failing to satisfy the control objective regardless of the control photosensor used. Systems employing an alternative, closed-loop proportional control algorithm achieved the control objective under virtually all tested conditions when operated by a ceiling-mounted photosensor shielded from direct window light.

Fifty percent energy savings with automatic lighting controls

An electronically ballasted lighting control system was demonstrated at an office building in the San Francisco Bay Area. The system was used to demonstrate the energy savings and demand-reduction capabilities of a lighting control system designed to exploit all major control strategies, including scheduling, daylighting, and lumen maintenance. After 9 months of operation, lighting energy savings of approximately 50% relative to previous usage have been consistently achieved. A novel, two-part control photocell that permits successful implementation of daylighting and lumen maintenance strategies was demonstrated. >

Lighting Controls in Commercial Buildings

Abstract Researchers have been quantifying energy savings from lighting controls in commercial buildings for more than 30 years. This study provides a meta-analysis of lighting energy savings identified in the literature—240 savings estimates from 88 papers and case studies, categorized into daylighting strategies, occupancy strategies, personal tuning, and institutional tuning. Beginning with an overall average of savings estimates by control strategy, successive analytical filters are added to identify potential biases introduced to the estimates by different analytical approaches. Based on this meta-analysis, the best estimates of average lighting energy savings potential are 24 percent for occupancy, 28 percent for daylighting, 31 percent for personal tuning, 36 percent for institutional tuning, and 38 percent for multiple approaches. The results also suggest that simulations significantly overestimate (by at least 10 percent) the average savings obtainable from daylighting in actual buildings.

Performance of electronic ballast and controls with 34 and 40 watt F40 fluorescent lamps

Electric and photometric characteristics have been compared for 40 W and 34 W F40 T-12 fluorescent lamps by operating them with electronic ballasts, static controls, and dynamic controls of different designs. The energy savings generated by a krypton-filled 34 W lamp system is, at best, slightly more efficacious than the standard 40 W argon-filled lamp system by virtue of the use of lite white phosphor. The 34 W system has limitations that include higher starting voltages, reduced temperature range of operation, smaller dimming range, and poorer color rendering than the standard cool white 40 W lamp system.<<ETX>>

Photoelectric control of equi-illumination lighting systems

Abstract The ability of a photoelectrically controlled lighting system to maintain a constant light level on a task surface by responding to changing daylight levels is affected by the control algorithm used to relate the photosensor signal to electric light levels and by the geometry and location of the photosensor. We describe the major components of a typical equi-illumination system, discuss the design and operation of such a system, and examine the effects of the control algorithm and photosensor shielding. Equations for the control photosensor signal are developed that separate the signal into electric light and daylight components. We then present mathematical descriptions for the constant set-point control algorithm used by most manufacturers. An alternative, sliding set-point algorithm is proposed in which the total photosensor signal is a linear function of the signals daylight component. Computer simulations of the performance of dimmable lighting control systems driven by ceiling-mounted photosensors were run for a test room under various daylight conditions. Control systems using the constant set-point algorithm were unable to provide the target light level continuously, although shielding the ceiling-mounted photosensor from the window luminance resulted in higher maintained levels with less variability than did using unshielded photosensors. The use of a sliding set-point algorithm in lieu of a constant set-point algorithm improved the performance of systems driven by both shielded and unshielded photosensors. When a sliding set-point system was used in conjunction with a photosensor shielded from the window, a nearly constant light level was maintained at the task surface regardless of daylight condition.

Preliminary Results from an Advanced Lighting Controls Testbed

Preliminary results from a large-scale testbed of advanced lighting control technologies at the Phillip Burton Federal Building at 450 Golden Gate Ave. in San Francisco are presented. The first year objective of this project is to determine the sustainable energy savings and cost-effectiveness of different lighting control technologies compared to a portion of the building where only minimal controls are installed. The paper presents the analyzed results from six months of tests focused on accurately characterizing the energy savings potential of one type of daylight-linked lighting controls compared to the lighting in similar open-planned areas without dimming controls. After analyzing a half year;s data, we determined that the annual energy savings for this type of daylight- linked controls was 41% and 30% for the outer rows of lights on the South and North sides of the building, respectively. The annual energy savings dropped to 22% and 16% for the second row of lights for the South and North, respectively, and was negligible for the third rows of lights.

Developing a Dynamic Envelope/Lighting Control System with Field Measurements

The feasibility of an intelligent venetian blind/lighting control system was tested in a 1:3 scale model outdoors under variable sun and sky conditions. The control algorithm, block direct sun and meet the design workplane illuminance level, was implemented using commercially available and custom designed blind and lighting systems hardware. While blocking direct sunlight, the blinds were properly controlled to maintain the design workplane illuminance within a tolerance of -10%, +25% when there was sufficient daylight. When daylight levels alone were inadequate, the electric lighting control system maintained the design workplane illuminance. The electric lighting could be turned off if a user-specified time period at minimum power was exceeded. Lighting energy savings of 51-71% (southwest) and 37-75% (south) was attained for the period from 8:00 to 17:00 on clear sunny days, compared to a fixed, partially closed blind with the same lighting system. Practical details for implementation and commissioning are discussed. The impact of control variations, such as profile angle, time step interval, and control area, on energy demand is investigated.

Demand Responsive Lighting: A Scoping Study

LBNL-62226 Demand Responsive Lighting: A Scoping Study Francis Rubinstein Lawrence Berkeley National Laboratory Sila Kiliccote Lawrence Berkeley National Laboratory 1 Cyclotron Rd. Building 90R3111 Berkeley CA 94720 January 3, 2007 This work described in this report was coordinated by the Demand Response Research Center and funded by the California Energy Commission, Public Interest Energy Research Program, under Work for Others Contract No. 500-03-026 and by the U.S. Department of Energy under Contract No. DE-AC02- 05CH11231.

Saving Energy with Highly-Controlled Lighting in an Open-Plan Office

Abstract An installation in a Federal building tested the efficacy of a highly-controlled, workstation-specific lighting retrofit. The study took place in 86 cubicles in an open office with low levels of daylight. A direct/indirect pendant luminaire with three 32 watt lamps, two DALI ballasts, and an occupancy sensor provided both task and ambient light for each cubicle. All three lamps turned on and off according to occupancy on a workstation-by-workstation basis. Field measurements taken over the course of several months demonstrated 40 percent lighting energy savings compared to a baseline that represents a typical Federal building retrofit; the baseline has a lighting power density of 8.9W/m2 (0.83W/ft2) and no advanced controls. A photometric analysis found that the installation provided higher desktop light levels than the baseline did, while an occupant survey suggested that occupants preferred the lighting system to the baseline. This document was prepared as an account of work sponsored by the United States Government. While this document is believed to contain correct information, neither the United States Government nor any agency thereof, nor The Regents of the University of California, nor any of their employees, makes any warranty, express or implied, or assumes any legal responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by its trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof, or The Regents of the University of California. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof or The Regents of the University of California.

Using Dimmable Lighting for Regulation Capacity and Non-Spinning Reserves in the Ancillary Services Market. A Feasibility Study.

The objective of this Feasibility Study was to identify the potential of dimmable lighting for providing regulation capacity and contingency reserves if massively-deployed throughout the State. We found that one half of the total electric lighting load in the California commercial sector is bottled up in larger buildings that are greater an 50,000 square feet. Retrofitting large California buildings with dimmable lighting to enable fast DR lighting would require an investment of about