Ergonomics, as it relates to lighting, is basically having the right amount and location of lighting for what you’re doing. In the workplace, it can be making sure computer monitors don’t have too much glare on them (to prevent eyestrain) or ensuring that people performing tasks that require precision and fine-detail work have lighting on a path that ensures that there are no shadows cast on what they’re doing.
In the home, having ergonomic lighting can mean installing task lighting above kitchen counters or a workbench or making sure that hallways and stairways have enough lighting in them for safety.
Making Sense of Measurements
You’ll find light levels are listed in lumens, which is light output. Light intensity levels may be listed in lux or foot-candles (fc). Lux measurements are roughly 10 times a foot-candle measurement, as a foot-candle is 1 lumen per square foot, and a lux is 1 lumen per square meter.
Incandescent light bulbs are measured in watts and may not have the lumen measurement on the packaging; for a frame of reference, a 60-watt bulb produces 800 lumens. Fluorescent lights and LED lights may already be labeled in lumens. Keep in mind that the light is brightest at its source, so sitting far away from a light will not provide you with the lumens listed on the packaging. Dirt on a lamp can cut into the light output as much as 50 percent as well, so it makes a real difference to keep bulbs, glass globes, and shades cleaned.
Room Lighting Levels
Outdoors on a clear day, lighting is approximately 10,000 lux. By a window inside, the available light is more like 1,000 lux. In the center of a room, it can drop dramatically, even down to 25 to 50 lux, hence the need for both general and task lighting indoors.
A broad guide is to have general, or ambient, lighting in a passageway or a room where you don’t perform concentrated visual tasks at 100–300 lux. Raise the level of light for reading to 500–800 lux, and concentrate task lighting on your needed surface at 800 to 1,700 lux. For example, in an adult’s bedroom, you need lighting to be lower to wind down your body for sleep. In contrast, a child’s bedroom may be where he or she studies as well as sleeps, so both ambient and task lighting would be needed.
Similarly, in dining rooms, the ability to change the number of lumens through different types of lighting (ambient or over the center of the table) or dimmer switches can make the space more versatile, from an active area during the day to a relaxing space in the evening. In the kitchen, pendant lights above islands and range hoods with lighting over the stove are additional ways to use task lighting.
The following is a list of minimum lighting levels for residential spaces.
|Bedroom (adult)||General||100–300 lux|
|Bedroom (child)||General||500 lux|
|Living room/den||General||300 lux|
|Family room/home theater||General||300 lux|
|TV viewing||150 lux|
|Dining room||General||200 lux|
|Hall, landing/stairway||General||100–500 lux|
|Home office||General||500 lux|