MAINTAIN CCT VALUES
Various studies have been made into the influence of CCT on the visual acuity and performance of people. In general, study participants preferred 4000 K to other CCTs and agreed that this light was the most visually comfortable. Participants also stated that they felt they would be comfortable working under light of 4000 K for more than 6 hours; longer than under both warmer light and even daylight. Therefore, scientists now recommend that educational institutions install new lighting with a cooler CCT in order to positively influence student performance and comfort. In addition, there should ideally be provided the option for users to select the most appropriate CCT for a given task, such as a higher CCT for performance of intricate or difficult tasks like microscope work or the solving of complex equations, or a more neutral CCT for tasks to be performed for a longer duration like writing. As CCT values are always influenced by outside sources of light, whether that be light from other luminaries or from daylight entering windows, it is of great advantage to employ devices that can measure ambient CCT parameters and control the lighting system accordingly to maintain a desired value. The DALI Ambient Sensor is just such a device, and can be used to not only maintain a desired CCT at a given time, but also to compensate for the colour shifting of LED light sources over time.