Are you dealing with complaints about overhead lighting?
To occupants' detriment, many offices overemphasize the familiar linear fluorescents but provide few to no alternatives. The resulting glare, shadows, and eye strain can lead to general discomfort, migraines, and even suboptimal productivity.
However, incorporating task lighting may offer a no-retrofits-required solution. Is your facility a good candidate for this simple fix?
A multi-tiered approach that doesn't rely solely on overhead lighting is recommended, as it allows some efficient use of the overhead (though perhaps not at full brightness) and lets you provide additional light wherever necessary.
"In the latest edition of RP1, the Illuminating Engineering Society's Recommended Practice for Office Lighting, the first thing we try to promote is an ambient, task, and accent approach to lighting within the space," explains Gary Woodall, senior designer for Gary Steffy Lighting Design, Inc. and the co-chair of IES's office lighting committee for the past six years.
"Optimize the ambient lighting to provide a general layer of light that covers the majority of the tasks within the space, such as circulation, visual communication with coworkers, wayfinding, and orientation," Woodall adds. "Then use task lighting to raise that level higher where necessary for close reading tasks and technology that requires higher light levels, like videoconferencing."
You can add supplemental lighting to spaces that need it with two basic types of task lighting: articulated task lights are standalone fixtures that you can easily add to an office or cubicle as needed, and undercabinet task lights are sometimes built into ready-to-assemble cabinets and desks.
You may already have undercabinet task lighting in your facility, but are occupants using it? Check to see if it's too bright, provides inadequate light, or is inconveniently located.
"It's important that task lighting deliver an appropriate amount of additional light, whether the fixture is undercabinet or freestanding," Woodall says. "There should be a way to spread the light across the desk evenly so it doesn't feel too bright. Undercabinet lighting should direct some light to the back surface under the cabinet in addition to what shines down on the desk."
How to Tailor Task Lighting
It's usually best to match the task light's color temperature to that of the ambient lighting to ensure optimal visual comfort, Woodall recommends.
IES issues guidelines for the recommended footcandle level for different applications – visual tasks with small detail and high contrast can require as much as 50 fc, while the same job with low contrast could require up to 100 fc, according to Mark Havira, director of national accounts for Efficient Lighting Consultants.
Placement and aesthetic considerations are also paramount in making sure your investment is actually put to use, Woodall adds. Examine where in their offices or cubicles occupants are completing tasks, then aim to provide soft light distributed evenly throughout the space.
Multiple task lights with lower wattages are likely to be more effective than one bright light, Woodall adds.
"One thing we've seen with the advent of many LED task lights is that you get grids or arrays of unshielded LEDs that result in harsh brightness," Woodall adds. "When you put your hand down on a piece of paper, you end up with multiple different shadows. That visual noise is distracting and makes it harder to focus on what you're trying to read or write."
Ensure Energy Savings
An easy way to save energy while incorporating task lighting is to adopt a sensible control scheme that prevents task lights from burning all day. Undercabinet lighting can benefit from dimming or step ballasts to adjust the brightness, while task lights of all types are good candidates for automation.
"Use occupancy sensors or a switching system that turns the light on when you're in your cubicle and off when you're away from your desk. You might not have to turn on the overhead light due to the presence of windows or other lights in the space," recommends Woodall. "Our experience has been that if we can educate the occupants that the task light is there and make it easy for them to use, they make good use of it."
Janelle Penny firstname.lastname@example.org is senior editor of BUILDINGS.