Tunable-white fixtures change the appearance of white light over a stated range. To specify them, check what happens to output, color quality, and dimming behavior across that range.
Separate the product feature from the design goal
A tunable-white lamp can change CCT. A lighting plan intended to support daily rhythms also needs the right intensity, timing, spectrum, and exposure at the eye. One feature does not establish the other.
Measure the relevant light
CCT is not a measure of biological effect. For a project with circadian-lighting criteria, use the metrics and measurement positions required by that brief. Account for daylight and where occupants actually sit or stand.
Ask for data across the CCT range
Compare delivered lumens, watts, Ra, R9, color tolerance, and minimum dim level at several CCT settings. Check for visible steps or color shifts while fading. Record whether the output is held constant or varies with the setting.
Check the chosen rating-system criteria
Use the current requirements for the specific certification pathway. A tunable-white product is not itself a WELL or LEED project certification. Identify what the lighting designer must calculate, measure, and document.
Make normal operation understandable
Agree on the daily schedule, manual override, reset behavior, and who can change settings. Confirm the driver and controller support the required color-control method. Include commissioning time and staff training.
Review a sample in the room
Compare the intended morning, daytime, and evening settings with the room finishes and daylight. Check glare and task visibility at each setting. Keep the final schedule and settings with the handover documents.
Frequently Asked Questions
Does warm white improve sleep?
CCT alone cannot predict sleep effects. Intensity, spectrum, timing, and exposure duration matter.
What should a tunable-white quote include?
The CCT range, performance at different settings, control interface, compatible controller, and commissioning scope.