Posts Tagged ‘LED Lighting’

There is a great deal of marketing noise professing the use of CCT white light tuning to enhance circadian function in work environments. The real question is whether this approach actually has any real-world effect on human response to light in the spaces it is being applied to.

Theoretically, the proposition is that by changing the CCT of light, one can affect circadian reaction – specifically increase or decrease melatonin suppression. The proponents of CCT tuning profess that, with no consideration of illuminance levels, cooler CCT’s will produce greater melatonin suppression, resulting in a more wakeful state, while warmer CCT’s will produce significantly less melatonin suppression, creating a more restful state that does not disrupt sleep cycles. The assumption is that illuminance levels required for proper task performance can be maintained, relying solely on a CCT change alone to impart the desired “Human Centric” benefit.

To test this, I created a test box that houses 5 different high CRI LEDs, with a dimmer. The CCT’s I chose are the popular 2700, 3000, 3500, 4000, and 5000K. All had >88CRI and >90Rf/94Rg (using TM30). The first test was to set illuminance at 50Fc, and measure the difference in Circadian Stimulus (RPI/LRC method), and Melanopic Lux (Well Buildings Standard). (more…)