Much has been spoken about the effects of colour and how this can impact directly on our Melatonin and Serotonin production. For the non lighter these are the chemicals that help to regulate our Day / Night cycle. Melatonin helps us to sleep and Serotonin stimulates and wakes us from our slumber. The science, one could argue is well documented and surprisingly isn’t that new a subject although you would be forgiven if you read the plethora of articles written on this topic.

Circadian Lighting, Human Centric Lighting call it what ever you like the premise is fairly straightforward if you look at it from a controls perspective. You manage the transition from one colour temperature to another through a series of steps or presets. Now I am over simplifying deliberately as I am trying to demystify some of the confusion around this subject.

I should add that the selection of the LED’s and Optics and the design of the luminaire are crucial. A poorly designed and conceived luminaire just wont work as well as a quality designed luminaire; you pays your money and take your choice. The selection of the driver is critical as the management of the LED’s on the boards will ultimately be undertaken by the driver and selection of the wrong driver can dramatically impact on performance.

DALI has developed a device type 8 that provides the frame work for colour control and with the right driver allows the selection of specific colour values to meet the demands of the most challenging of lighting projects.

Selecting the correct driver and the appropriately designed luminaire is part of the system that will ultimately deliver your lighting project. In essence you have the backbone and now we need to consider how we manage the system.

Recalling and cross fading between different colour temperatures based on Device type 8 commands is fairly straightforward and we have done this in a number of applications all based around IEC 62386 Part 102 DALI. Applications have arranged from commercial to health applications, with a recent installation within the recovery wards of a Hospital based in the Midlands.

Key to simplifying the process was to control all of the functionality within a common standard that provides interoperability and a known interface; no special protocols or equipment required.

The greatest challenge with Human Centric Lighting is in tailoring the lighting to the Application. Performance specifications are just that and need a good deal of fine tuning to match the specific requirements of the application. Location of furniture and the reflectance of surfaces can have a huge impact on the visual experience. We should also consider intensity as well. The colour is just one aspect of Human Centric Lighting, controlling stimulus with intensity can also help to reprogram the Light /Dark cycle in shift works for example and sometimes the intensity of the lighting may have a more fundamental impact on the user rather than the pure colour.

My lighting designer friends are better qualified to comment on the visual aspect of Human Centric Lighting, the aim of this article is to try and promote the use of controls within Human Centric Lighting and to really say that from a pure controls point of view it’s not that complex.

What is complex, is the selection of the presets and the intensity of each preset over the working day. There are models but these need to be tailored to your particular application and in reality these will always require some form of Post Occupancy Evaluation.

Its also worth noting that we have equipped our sensors to measure background colour and therefore report back to the zencontrol head end the change in relative colour. Also as a cloud based controls system, amending the system timings, colour and intensity is something that can be handled remotely.

Human Centric Lighting has the ability to dramatically impact on how we interact within the spaces we occupy and as a science it truly will have an impact on our well being. As a controls solution its affordable and something that should be considered for all buildings.

Stewart Langdown FSLL

m+44(0)7774 821093