Mary Matteson Bryan, P.E Bi-Level Office Lighting with Occupancy Sensors E3T Field Assessment Mary Matteson Bryan, P.E. January 14, 2011

2 Background Concepts – Heat Mgmt Bi-level Office Lighting with Occupancy Sensors Courtesy CLTC CLTC Study - with the option of bi-level switching, occupants often choose to use a lower light level Up to 50% savings

3 Background Concepts – Heat Mgmt Field Assessment Goals Validate and add to CLTC findings for NW applications Quantify energy savings Develop economic analysis (customer simple payback) Provide energy savings data to support incentives Document occupant acceptance Develop case study Develop specifications Provide NW test installation

4 Background Concepts – Heat Mgmt Baseline and Proposed Measures Worked with BPA program staff to define baseline and proposed measures Define baseline per BPA lighting calculator Calculator assumes single-level (100%) manual switching Define proposed measures Rewire to bi-level switching with occupancy sensor For this assessment, also included ballast change to provide uniform illumination at 50%

5 Background Concepts – Heat Mgmt Host Site: Pierce County High level of interest in energy efficiency, sustainability Individual offices, both perimeter with daylighting and interior Monitoring 30 offices Existing control: manual single level switching (all lights on or off) County-City Building

6 Background Concepts – Heat Mgmt Experimental Design and Procedure Monitor each of three operational scenarios. Auto On at 50%/Auto Off: Lights are switched on automatically at the low level (50%) upon occupancy, the remaining lights can be switched on manually. Auto On at 100%, Auto Off: Lights are switched on automatically at the high level (100%) upon occupancy, lights can be switched to a lower light level (50%) manually. Manual On/Auto Off: Lights can be switched on and off manually at 50% or 100%. In all cases, lights can be switched off manually, and lights are turned off automatically after the office is unoccupied for a period of time.

7 Background Concepts – Heat Mgmt Project Results Lighting Operation Significant operation at the low light level setting with bi-level switching as compared to the baseline manual, single level. Maximum operation at low (66% of lit hours) using the auto-on at 50% setting.

8 Background Concepts – Heat Mgmt Project Results Energy Savings Greatest energy savings achieved with the Auto-on at 50% setting. Note that savings are different for the retrofit and new construction cases because of the different baseline lighting hours of operation.

9 Background Concepts – Heat Mgmt Project Results Occupant Satisfaction Occupants had very favorable reactions to the bi-level switches and occupancy sensors. Most occupants (64%) preferred the Auto-on at 50% setting.

10 Project Results Economic Performance Economic estimates are sensitive to site-specific variables such as lighting hours of operation, installation labor costs, utility incentives, and energy costs. Economic calculations presented here are based on variables specific to this field assessment. Energy Savings (kWh/yr) Energy Cost Savings ($/yr) Installed Cost ($) Payback (yrs) Small Office, New Construction64$5.62$509 Large Office, New Construction194$17.04$1106 Small Office, Retrofit85$7.47$36048 Large Office, Retrofit254$22.31$87039 Assessment Site Specific Analysis

11 Project Results Economic Performance - Impact of Lighting Hours of Operation and Installation Labor Costs

12 Project Results Economic Performance As a point of reference, economic performance was calculated for a hypothetical situation with more favorable, put reasonable, assumptions for baseline lighting hours and installed cost than those found for this assessment. Energy Savings (kWh/yr) Energy Cost Savings ($/yr) Installed Cost ($) Payback (yrs) Small Office, New Construction354$10.26$222 Large Office, New Construction1062$30.78$241 Small Office, Retrofit131$11.51$26823 Large Office, Retrofit393$34.52$63818 Favorable Assumptions Analysis

13 Conclusions Bi-level switching in individual offices can deliver significant savings as compared to single level switching. Energy savings are maximized when the switches are set to automatically turn on at the low light level setting. Bi-level switching provides high occupant satisfaction with the lighting system, possibly delivering non-energy benefits. The economic performance of bi-level switching is most favorable in a new construction/major remodel situation.

14 Background Concepts – Heat Mgmt Thank You Mary Matteson Bryan, P.E