Observations:
I was curious about how much light was reaching my desk at home, so I measured the light levels and recorded a range from 25 to 30 lux. Even with the window open, light levels at my desk were only 32 lux. I began to measure other surfaces throughout the space, with similar findings. Sitting on my bed, where I often read, I was measuring only 25 lux on my lap. In my dress area, I was measuring 30 lux on my full-body mirror.
The Illuminating Engineering Society recommends closer to 300 lux for tasks such as reading, writing, and dressing. This means that my room’s light levels at task planes were only one-tenth what IES recommends.
The lighting in my room was non-uniform, with a warm color temperature (3000K). Using Flynn’s lighting cues, the room could have been described as pleasant or relaxed.
Here are images of the luminaires in my room:
Hypotheses:
1. The light levels in my bedroom and office needed to be increased to 300 lux on task planes to improve my productivity. (Based on IES Illuminance Recommendations for reading, writing, and dressing)
2. I needed to change the color temperature of my lamps to 5000K, which is considered near to daylight, to promote a business-like environment. (Based on IES Recommended Practices for Lighting Educational Facilities)
3. Along with increasing light levels, I also needed to mitigate visual fatigue and promote visual clarity by providing more even light levels. (Based on Flynn’s lighting cues, and IES Recommended Practices)
Experiment:
1. To increase general light levels, I changed all of my light bulbs from 13W CFLs to 20W CFLs.
2. I made sure all the new CFLs were 5000K (daylight), to promote a business-like environment.
3. To increase light levels on task planes in particular, I considered luminaire distribution patterns and placement. See Figures 1 and 2 to get an idea for how moving the luminaires changed the distribution of light within the space.
Figure 1, Luminaire Locations and Light Distribution Before Intervention:

Notes:
-Light penetration into the room is inadequate.
-Light is not reaching the actual task planes of desk, bed, and mirror.
Figure 2, Luminaire Locations and Light Distribution After Intervention:

Notes:
-Light penetration into the room is better.
-Light is reaching the actual task planes of desk, bed, and mirror.
Evaluation:
The change in lamps from 13W CFLs to 20W CFLs increased the light output of each luminaire, while the 5000K color temperature does seem brighter and clearer. However, new lamps alone were not enough to significantly increase light levels at task planes. The greatest benefit came from the proper positioning of luminaires.
The linear fluorescent luminaire (Type A), remained above my cabinet, where it functions as an upper-cabinet luminaire to increase general light levels throughout the space.
The aim-able table luminaire (Type B), is now being used to throw light throughout the dress area. It is being aimed at the wall near my full-length mirror, where the light then reflects onto the nearby dresser and anybody standing in front of the mirror.
The aim-able wall-mounted luminaire (Type C), is now being used above my bed as a reading lamp. The ability to mount it almost directly above my reading surface and aim the light downward, without seeing the light source, made it an excellent task light for reading in bed. This luminaire was previously mounted in the dress area, where many of the directional qualities of this luminaire were being wasted as a wall washer. This repositioning boosted light levels on my lap for reading in bed.
The table luminaire (Type D), is now being used at my desk. It features a light diffusing shade, which allows more light to be cast on my work surface while preventing glare. I am now measuring from 150-300 footcandles on my desk, a range which allows for visually demanding tasks such as reading and writing, while levels become dimmer near my computer monitor for visual comfort. This luminaire previously was fitted with a 13W CFL and placed on my nightstand, where none of the light was reaching my lap for reading. This repositioning was a major improvement for light levels at my desk.
After spending a week in the brighter environment, I can report a definite increase in alertness. Reading comfortably is now possible at several different locations in the room. Also, the 5000K color temperature does seem to arouse associations of business and productivity.
This improvement in alertness came with a small cost: the room lacks a relaxing light setting for entertaining company. All of the luminaires are cold, bright, and unable to be dimmed, so even if I only turn on one half of my fixtures, the lighting in the room feels much less pleasant than before.
Download the PDF: Case Study – Increasing Light Levels to Promote Alertness
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