Correlated color temperature, or CCT, describes the appearance or tint of a particular light, ranging from warm to cool. CCT is measured in degrees Kelvin on a scale from 1000 to 10000. The warmer a light is, the lower its temperature will be. A cooler temperature will have a higher value.
Here’s a rough guide to how each temperature range should be used:
Warm White in the 2000-3000 CCT range is ideal for dining rooms, restaurants or commercial ambient lighting.
Cool White in the 3100-4500 CCT range can help people stay alert and is well suited for work environments, kitchens and restrooms.
Bright White in the 4600-6500 CCT range is similar to daylight and may be needed for task lighting, display areas, security lighting or garages
Wattage also plays a major role in how employees feel and perform at work.
Dimmer light may not be adequate for focused task work like assembling parts or reading spreadsheets. It may cause eyestrain and headaches because the eyes must work harder to see. This can also cause drowsiness and lack of focus, especially when an afternoon energy dip kicks in.
On the other end hand, too bright lighting can also cause eyestrain, and has been known to trigger migraine headaches. It can also interfere with employees’ circadian rhythm that regulates sleep. Well rested employees can be more productive.
The key is to look at how the lighting benefits the people using it. Not only should the lighting be optimal for the work being done, it should not detract from the employee’s health. (Mark Halper at LEDs magazine wrote an excellent piece in 2017 about how lighting affects our circadian rhythms – as it turns out, blue frequency light at night is really, really bad for us.) This is what makes selectable wattage and color temperature fixtures such a slam-dunk for today’s more human-centered workspaces.
