ARCHIVED - Personal controls save energy
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April 08, 2008— Ottawa, Ontario
|Personal lighting controls, as shown in the inset, allow cubicle dwellers to choose their own lighting levels.|
Office buildings equipped with both automatic and personal lighting controls can achieve major energy savings compared with conventional lighting systems — while improving the environmental and job satisfaction of office workers, according to a recent NRC study.
The study — conducted in partnership with the federal government's Program on Energy Research and Development, Public Works and Government Services Canada, BC Hydro Power Smart, and Ledalite Architectural Products — looked at the performance of a commercial lighting system that features three types of controls. These included occupancy sensors that gradually switch off lights when people leave a work area, light sensors that slowly dim lights when there is enough daylight to maintain illumination levels, and personal lighting controls that workers operate from their computer screens.
"A truly sustainable building can only be sustainable if it provides conditions that are pleasant and satisfactory to occupants as well as being environmentally friendly," says Dr. Guy Newsham, who leads the lighting research group at the NRC Institute for Research in Construction (NRC-IRC). "Our main interest is how to improve the satisfaction, comfort, mood and performance of people in buildings, using lighting systems."
Today, some green-minded workplaces have occupant and light sensors, but few have invested in personal lighting controls. "In a typical North American office environment, everyone gets the same light level regardless of personal preferences," says Dr. Newsham. "Personal lighting controls would allow people to choose their own workstation lighting level, largely independent of what their neighbours might want."
Reducing peak demand
When demand for electricity rises rapidly — especially on hot summer afternoons when air conditioners are on full blast and office lighting is still being used — brownouts or blackouts may occur. To prevent grid stress, many utilities are interested in load shedding, which involves signalling large power users such as commercial buildings to reduce electricity use.
With federal government and industry partners, Dr. Newsham's group is studying how far and how fast office buildings can lower their lighting and cooling requirements before workers start to notice. "The goal is to do this so that, at least initially, it will not affect people. Of course, in a greater emergency more extreme measures might be required," he says.
In lab studies, the group found that in work settings where no daylight is available, "you can only dim the electric lights by about 20 percent over a 10 second period without most people noticing. But if you dim them more slowly, over half an hour and in a daylit setting, you can dim the lights by about 50 percent for a few hours and the majority won't notice," says Dr. Newsham. "And we've raised office temperatures by 1.5 degrees (from 22 to 23.5 degrees) over a three hour period, without most people noticing the increase." This summer, his team plans to verify these findings in a real office or college building.
"Some workers use those controls to choose higher light levels than are recommended by prevailing standards," he adds. "But we've found that workplaces, on average, will save energy because more people tend to choose lower levels. And since they have personal controls, office workers can turn their lights off when they leave and turn them on when they arrive in the morning."
The NRC research team found that the combination of automatic and personal lighting controls reduced energy use by about 70 percent over a year-long period. "Most of these savings came from the automatic sensors, while the personal controls accounted for about 10 percent of the total energy savings," says Dr. Newsham.
"However, we also found that personal lighting controls improved both the personal and job satisfaction of office workers. So if you look at the intangible benefits they provide to occupants, we believe that over the long term an investment in this technology will pay off," he concludes. "We hope these findings will give building owners, managers, and practitioners more confidence to adopt such controls, to the benefit of the occupants and the environment."
Enquiries: Media relations
National Research Council of Canada
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