The Hues of White
LEDs can produce all colors across the visible spectrum. Every color of light has a range of hues, and LEDs can theoretically produce every variation visible to the human eye. But for our purposes we will only discuss the range of “white” light.
From the warm glow of a candle to the cool blue wash of an overcast day, we’re familiar with these natural variations already . We probably don’t think much about the color of white light- until we encounter a bad lighting design. Understanding color will help avoid an annoying, unhealthy and expensive design mistake.
Warm to Cool
The hues of white light start on the warm end of the scale. This is similar to candle light, followed closely by the familiar yellow glow of halogen lamps common to most residential lighting. The midrange is a neutral or ‘bright’ white, common to most well designed office environments and retail spaces. This color casts a clean, clear light without distorting color too far into the blue range and appearing harsh. Then we have cool white on the far end of the scale. This is the color of daylight, and can appear very blue when used in an interior lighting design.
The scale itself is measured in terms of color temperature, expressed in degrees Kelvin. Halogen light is about 2800K and daylight is about 6000K.
While every circumstance is different, here are some very general suggestions for choosing the right color temperature. Interior lighting for homes and restaurants should stay in the warm range, to create a serene atmosphere. For most commercial and retail interiors, 4000K is highly recommended. Rooms are bright and safely lit for daily tasks with little color distortion. Exterior accent lighting should also stay in the warm white to mid range, 4000K maximum. 5000K or 6000K may be appropriate for exterior security lighting.
Design For Good Health
There are subconscious and biological effects of lighting that should not be dismissed lightly. Artificial lighting is relatively new in terms of human history, yet our minds and bodies release powerful responses to light that have been consistent for thousands of years. Sunrise is warm in color, while midday is a bright blue. Sundown is a return to warm colors, then firelight and candlelight create a calming atmosphere as our energy runs low and we approach sleep.
This is the time when the hormone melatonin is released, which triggers drowsiness. The daily cycle of sleep and other biological functions are known as circadian rhythm. Melatonin production is closely linked to the eye perceiving warm colors, so using cool white lighting in the evening is actually counterproductive to good health.
A good lighting design cooperates with nature to create an ideal living and working environment for maximum health and productivity.