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Bi-Level Office Lighting with Occupancy Sensors

Bi-Level Office Lighting with Occupancy Sensors. E3T Field Assessment Mary Matteson Bryan, P.E. January 14, 2011. Bi-level Office Lighting with Occupancy Sensors. Background Concepts – Heat Mgmt.

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Bi-Level Office Lighting with Occupancy Sensors

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

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

  3. Field Assessment Goals Background Concepts – Heat Mgmt • 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. Baseline and Proposed Measures Background Concepts – Heat Mgmt • 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. Host Site: Pierce County Background Concepts – Heat Mgmt • 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. Experimental Design and Procedure Background Concepts – Heat Mgmt • 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. Project Results Background Concepts – Heat Mgmt • 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. Project Results Background Concepts – Heat Mgmt • 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. Project Results Background Concepts – Heat Mgmt • 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. 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. 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. Thank You Background Concepts – Heat Mgmt Mary Matteson Bryan, P.E. 415.305.5445 marymattesonbryan@pacbell.net

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