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Project Leader
Guy Newsham
Phone: 613-993-9607
Fax: 613-954-3733
Email: Guy.Newsham@nrc-cnrc.gc.ca
Task Lighting Effects on Preferred Office Lighting and Energy Savings
Objectives
To evaluate whether task lighting in offices will reduce occupants' preferred ambient lighting level, leading to savings in office lighting load.
Background
Many recommended practices claim that savings in lighting energy and peak electrical load of up to 40% can be achieved by reducing ambient lighting levels in offices and using task lighting of much lower wattage. Previous research on this topic is equivocal, and does not reflect modern North American office conditions, tasks, or cultural expectations. Therefore, there was a need to test the appropriateness of task – ambient lighting solutions to avoid possible satisfaction-related problems.
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| Task lighting provided by lamp with luminous shade |
Statement of Work
The research was conducted in a full-scale mock-up office containing two open-plan workstations. Ambient lighting was provided by dimmable ceiling-recessed deep-cell two-lamp parabolic troffers. One workstation had an angle-arm desktop light fixture and the other a table lamp with luminous shade. The task lights were set at various levels of output (including zero) and research participants chose their preferred ambient light level in response to the task light setting.
Results
- Participants did not dim ambient lighting substantially when given task lighting. This is likely because people want adequate lighting on all room surfaces, and comfortable luminance ratios between room surfaces. This suggests that pursuing large energy savings by cutting back considerably on ambient lighting and providing a task light may backfire in the long-term by creating sub-optimal lighting conditions.
- Current recommended practice for ambient lighting on the desktop of 400-500 lx is appropriate based on average occupant preferences. However, recommended practice for vertical partition illuminance should be revised upward, to 200-250 lx.
Outcomes
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Report containing the results and implications for achieving energy savings in practice
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A scientific journal article
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Technology transfer to practitioners
Partners
Climate Change Plan for Canada, Technology and Innovation R&D Initiative (CCTI),
BC Hydro Power Smart
Start/Completion Dates
The project began in March 2003 and was completed in July 2004.
Publications
Experiments demonstrate effects of task lighting on office workers and energy consumption
Newsham, G.R.
Construction Innovation, 10 (3)
pp. 9-10. 2005-09-01
[Full citation / Référence complète]
Task lighting effects on office worker satisfaction and performance, and energy efficiency
Newsham, G.R. Arsenault, C.D. Veitch, J.A. Tosco, A.M. Duval, C.L.
Leukos, 1 (4)
pp. 7-26. 2005-04-01
[Full citation / Référence complète]
Effect of dimming control on office worker satisfaction and performance
Newsham, G.R. Veitch, J.A. Arsenault, C.D. Duval, C.L.
IESNA Annual Conference (Tampa, Florida, 2004-07-26)
pp. 19-41. 2004-07-01
[Full citation / Référence complète]
Lighting for VDT Workstations 2: Effect of Control and Lighting Design on Task Performance and Chosen Photometric Conditions
Newsham, G.R. Veitch, J.A. Arsenault, C.D. Duval, C.L.
Research Report, NRC Institute for Research in Construction, 166
pp. 62. 2004-03-17
[Full citation / Référence complète]
Lighting for VDT Workstations 1: Effect of Control on Energy Consumption and Occupant Mood, Satisfaction and Discomfort
Newsham, G.R. Veitch, J.A. Arsenault, C.D. Duval, C.L.
Research Report, NRC Institute for Research in Construction, 165
pp. 46. 2003-04-30
[Full citation / Référence complète]
