Design & Engineering Services DC Power Grid System Lighting for a Typical Conference Room Evaluation ETO 09.03 Report Prepared by: Design & Engineering Services Customer Service Business Unit Southern California Edison November 2, 2009
Acknowledgements Southern California Edison s (SCE) Design & Engineering Services (D&ES) group is responsible for this project. It was developed as part of SCE s Education, Training, and Outreach program under internal project number ETO 09.03. D&ES project manager Doug Avery conducted this technology evaluation with overall guidance and management from Ramin Faramarzi. For more information on this project, contact doug.avery@sce.com. Disclaimer This report was prepared by SCE and funded by California utility customers under the auspices of the California Public Utilities Commission (CPUC). Reproduction or distribution of the whole or any part of the contents of this document without the express written permission of SCE is prohibited. This work was performed with reasonable care and in accordance with professional standards. However, neither SCE nor any entity performing the work pursuant to SCE s authority make any warranty or representation, expressed or implied, with regard to this report, the merchantability or fitness for a particular purpose of the results of the work, or any analyses, or conclusions contained in this report. The results reflected in the work are generally representative of operating conditions; however, the results in any other situation may vary depending upon particular operating conditions. Southern California Edison
ABBREVIATIONS AND ACRONYMS AC DC kw kwh PV VAC VDC W Alternating current Direct current Kilowatt Kilowatt-hour Photovoltaic Volts alternating current Volts direct current Watt Southern California Edison Page i
FIGURES Figure 1. Post-Retrofit Conference Room...7 Figure 2. DC Power Connector on the Ceiling Grid...7 Figure 3. Nextek Power Server Post-Retrofit...7 Figure 4. Intu Control Node...7 Figure 5. Ceiling Mounted DC Power Grid...7 Figure 6. Synergistic Logger Box...8 Figure 7. Electric Panel...8 Figure 8. Load Profile of Conference Room Lighting...9 Figure 9. Average Weekday Lighting kw Baseline and Post- Retrofit... 10 Figure 10. Average Weekend Lighting kw Baseline and Post- Retrofit... 10 Southern California Edison Page ii
CONTENTS EXECUTIVE SUMMARY 4 INTRODUCTION 5 PRODUCT DESCRIPTION 5 TECHNICAL APPROACH 8 RESULTS AND RECOMMENDATIONS 9 Results...9 RECOMMENDATIONS 11 Southern California Edison Page iii
EXECUTIVE SUMMARY The main objective of this study is to determine if there are any energy savings associated with the installation of a direct current (DC) power grid and associated controls in the Southern California Lighting Technology Center s (SCLTC) conference room. The efficiency of this new system will be compared to the baseline lighting and controls system operating on an alternating current (AC) circuit. Three industry partners provided the material for the installation of the system. Armstrong Building Products provided the grid work for the ceiling mounted DC power distribution. Nextek Power Systems provided a power server as well as DC lighting ballasts. Kanepi Innovations provided the sensors and other equipment for the lighting control system. Although new lighting ballasts were installed for this project, the baseline lighting fixtures were not replaced. During the baseline period of November 5, 2008 through February 17, 2009, excluding holidays, the weekday peak lighting load ranged from 0.004 kw to 0.436 kw. During the post-retrofit period of June 4, 2009 through July 14, 2009, excluding holidays, the weekday peak lighting load ranged from 0.008 kw to 0.073 kw. The annualized conference room lighting energy use decreased from 324 kwh in the baseline period to 156 kwh in the post-retrofit period - a decrease of 52%. It is important to note that the savings was obtained by programming the lighting system to operate only when the space was occupied and by requiring a manual on to select the lighting scene that provided the desired lighting levels for each specific meeting. Southern California Edison Page 4
INTRODUCTION The objective of this project was to determine power and energy savings associated with conversion of an AC lighting system to a DC system. The baseline energy use for the installed lighting system normally operates on an AC circuit. The existing lighting fixtures were retrofitted to operate on DC power, and the DC grid was installed. A new baseline for the energy use of the DC system was recorded. The next potential step is to install Photovoltaic (PV) cells on the roof and measure the energy use of a DC-to-DC lighting system. PRODUCT DESCRIPTION The existing lighting system in the conference room consists of: Three suspended fixtures with two 4-foot 28W T-5 lamps. Three recessed fixtures with one 4-foot 28W T-5 lamp. One recessed fixture with two 2-foot 40W biaxial lamps. The materials for this project were provided by three industry partners and are listed below: Armstrong Building Products provided: Ultima Tegular 2x2 ceiling tiles for the conference room area above the conference table and for private offices (shown in Figure 1). New Tierra High Light Reflectance (LR) and rapidly renewable lay-in 2x2 ceiling tiles for the conference room area by the front hallway. A new ceiling suspension system, including wall moldings, main beams, and cross tees. A silhouette style in the Ultima ceiling areas and a Suprafine style in Tierra ceiling area. (All grid main beams are new Armstrong DC power versions compatible with the draft EMerge Alliance standard.) All of the DC power connectors (shown in Figure 2) and cable assemblies required for connectivity between the Armstrong power grid and Nextek power server, and between all lighting devices, Kanepi devices, and the occupancy sensor and the grid. Nextek Power Systems provided: One 16-channel AC-DC power server compatible with later integration to solar panels (shown in Figure 3). The DC lighting ballasts that mate with the conference room lighting fixture schedule provided by SCE. Southern California Edison Page 5
Kanepi Innovations (formerly Light Corporation) provided: One web-based Intu control system panel assembly (includes the gateway as well as a touch screen for wall installation). Ten 24vdc multiple Intu nodes (shown in Figure 4). One 24vdc Watt Stopper daylight sensor. Two occupant sensing Watt Stopper wall switches. The new lighting equipment listed above was installed in February 2009, and the controls were tuned in June 2009. During the period after the installation of the lighting equipment and prior to the tuning of the controls, the new lighting fixtures were operating continuously. Southern California Edison Page 6
Figure 2 through Figure 6 show various components of the new lighting distribution system. FIGURE 1. POST-RETROFIT CONFERENCE ROOM FIGURE 2. DC POWER CONNECTOR ON THE CEILING GRID FIGURE 3. NEXTEK POWER SERVER POST-RETROFIT FIGURE 4. INTU CONTROL NODE FIGURE 5. CEILING MOUNTED DC POWER GRID Southern California Edison Page 7
TECHNICAL APPROACH In early November 2008, a synergistic multi-channel data recorder logger was installed to record the conference room electric lighting load. This type of logger records true root mean squared (RMS) power measurements for 120 volts alternating current (VAC) or 277 VAC electric loads, either single phase or three phase. Baseline and post-retrofit data was recorded in 15-minute intervals. Figure 6 shows the synergistic logger above the conference room ceiling. The logger was connected to the electric panel, shown in Figure 7, with a breaker to the conference room overhead lighting. During the post-retrofit period, the power of the DC lighting system and controller was monitored as two separate loads. For analysis purposes, both loads were combined as the total energy use of the overhead conference room lighting. After installation of the monitoring equipment, the SCE staff periodically gathered the monitored data. FIGURE 6. SYNERGISTIC LOGGER BOX FIGURE 7. ELECTRIC PANEL Southern California Edison Page 8
RESULTS AND RECOMMENDATIONS This section presents and discusses the data collected from monitoring the retrofitted lighting, as well as recommendations based upon the results. RESULTS The conference room does not have a regular schedule of occupancy. The average and maximum daily conference room lighting load from November 5, 2008 to July 14, 2009, shown in Figure 8. During the baseline period of November 5, 2008 through February 17, 2009, excluding holidays, the weekday peak lighting load ranged from 0.004 kw to 0.436 kw. During the post-retrofit period of June 4, 2009 through July 14, 2009, excluding holidays, the weekday peak lighting load ranged from 0.008 kw to 0.073 kw. 0.50 0.45 0.40 Baseline Post-Retrofit 0.35 0.30 kw 0.25 0.20 0.15 0.10 0.05 0.00 11/5/08 11/19/08 12/3/08 12/17/08 12/31/08 1/14/09 1/28/09 2/11/09 2/25/09 3/11/09 3/25/09 4/8/09 4/22/09 5/6/09 5/20/09 6/3/09 6/17/09 7/1/09 Date Average Daily kw Peak Daily kw FIGURE 8. LOAD PROFILE OF CONFERENCE ROOM LIGHTING Figure 9 shows the average weekday lighting electric load during the baseline period of November 5, 2008 through February 17, 2009, and during the post-retrofit period of June 4, 2009 through July 14, 2009. During the baseline period, the average weekday lighting load peaked at 0.118 kw at 3:00 PM. During the post-retrofit period, the average weekday lighting load peaked at 0.035 kw at 2:45 PM. Figure 10 shows the average weekend lighting electric load during the baseline period and during the post-retrofit period. During the baseline period, the average weekend lighting Southern California Edison Page 9
load peaked at 0.019 kw at 1:30 PM. During the post-retrofit period, the average weekend lighting load peak at 0.012 kw at 11:45 AM. 0.14 0.12 0.10 0.08 kw 0.06 0.04 0.02 0.00 12:00:00 AM 12:45:00 AM 1:30:00 AM 2:15:00 AM 3:00:00 AM 3:45:00 AM 4:30:00 AM 5:15:00 AM 6:00:00 AM 6:45:00 AM 7:30:00 AM 8:15:00 AM 9:00:00 AM 9:45:00 AM 10:30:00 AM 11:15:00 AM 12:00:00 PM 12:45:00 PM 1:30:00 PM 2:15:00 PM 3:00:00 PM 3:45:00 PM 4:30:00 PM 5:15:00 PM 6:00:00 PM 6:45:00 PM 7:30:00 PM 8:15:00 PM 9:00:00 PM 9:45:00 PM 10:30:00 PM 11:15:00 PM Time Baseline Post-Retrofit FIGURE 9. AVERAGE WEEKDAY LIGHTING KW BASELINE AND POST-RETROFIT 0.025 0.020 0.015 0.010 0.005 0.000 12:00:00 AM 12:45:00 AM 1:30:00 AM 2:15:00 AM 3:00:00 AM 3:45:00 AM 4:30:00 AM 5:15:00 AM 6:00:00 AM 6:45:00 AM 7:30:00 AM 8:15:00 AM 9:00:00 AM 9:45:00 AM 10:30:00 AM 11:15:00 AM 12:00:00 PM 12:45:00 PM 1:30:00 PM 2:15:00 PM 3:00:00 PM 3:45:00 PM 4:30:00 PM 5:15:00 PM 6:00:00 PM 6:45:00 PM 7:30:00 PM 8:15:00 PM 9:00:00 PM 9:45:00 PM 10:30:00 PM 11:15:00 PM kw Time Baseline Post-Retrofit FIGURE 10. AVERAGE WEEKEND LIGHTING KW BASELINE AND POST-RETROFIT Southern California Edison Page 10
The annualized conference room lighting energy use decreased from 324 kwh in the baseline period to 156 kwh in the post-retrofit period a decrease of 52%. The decrease is primarily due to the tuning of the controls system to ensure lights were off when not in use and because the lighting system required a manual on and directed the user to select the appropriate scene that would provide the lighting needed for each specific meeting. RECOMMENDATIONS A successful installation of DC-powered lighting with controls was demonstrated in this project evaluation. SCE is looking at zero net energy buildings and as a result, a decision was made to expand this project to include a larger area of the test site to include a kitchen, multiple bathrooms, a hallway, and a manager s office. The preliminary results of this study indicate that there is potential for significant savings to be realized using a DC power grid directly powered by a PV grid producing DC power. It is recommended that a second phase evaluation to study how a typical conference room, kitchen, bathrooms and a manager s office, equipped with a DC power grid and DC-adapted fixtures and appliances can be integrated into a solar PV power distribution, and be done without efficiency losses due to AC power conversion. Southern California Edison Page 11