There are three main types of tunable lighting systems – each with its own strengths and weaknesses.
Aiming to mimic incandescent lamps, dim-to-warm tunable lighting usually operates at color temperatures of 2700-3000K, and the light color becomes warmer in appearance as lighting dims.
“There are a number of different ways of doing dim-to-warm. It typically involves switching between cool and warm white LEDs. Some people add a red LED to get the warmer color temperatures, but that’s a more complicated design,” says Bob Karlicek, Director of Lighting Enabled Systems & Applications (LESA), a National Science Foundation engineering research center at Rensselaer Polytechnic Institute.
Ultimately, dim-to-warm tunable lighting has limited potential for many commercial spaces. According to the Department of Energy (DOE), dim-to-warm tunable lighting is ideal in restaurants, hotel lobbies, guestrooms, ballrooms, theaters and residential spaces.
White tuning allows users to change the color of light from warm to neutral to cool in appearance. These products have at least two sets of controllable LEDs, typically including a warm white color (around 2700K) and another at a cool white color (5000-6500K).
For facilities that want to dim lighting without affecting color temperature, whitetunable lighting might be a very good solution.
“Sometimes users want to reduce light output without changing color,” notes the DOE. “In these situations (such as in a conference room), it would be helpful to have dimming control that’s separate from color change – so white-tuning might be the better choice.”
Other benefits of white-tunable lighting, according to the DOE, include:
- Providing apparent cooling or warming to a room. This includes psychological effects like using cooler-color lighting to make occupants feel cooler on a hot day or vice versa.
- Matching the color of daylight in a lobby with windows by tuning the light to be warmer early in the morning and late in the afternoon, while tuning it to be cooler during the middle of the day, for example.
- Assisting with behavior control. Anecdotal classroom studies suggest tunable lighting can calm students, invigorate them or focus their attention.
- Supporting the human circadian system. Tuning the intensity and the spectral content of light can help stimulate or suppress melatonin production. These mechanisms aren’t fully understood yet but are a main area of focus for research.
- Correcting circadian misalignment. Adjusting light color and intensity may be used to treat jet lag, sleep disorders and other conditions.
The most sophisticated and experimental tunable lighting systems are colortunable. They include at least three LEDs of different colors that can create a mixture of light that is white, a tint of white or a saturated hue, explains the DOE. They can provide a wider range of lighting color, but they require a much more complicated control system.
“Color-tunable lighting consists of carefully timed and programmed control of spectral power distributions with an eye toward replicating daylight variations throughout the day to provide a low-blue content color tunable lighting at night,” says Karlicek. “Those kinds of systems are still experimental and being developed. They are increasingly being evaluated in research labs, healthcare facilities and schools.”