Human Centric Lighting (HCL) is lighting specifically designed to produce a beneficial physiological and/or psychological effect upon humans.
HCL uses the artificial lighting sources to create visual environments that mimic the natural daylight that drives and interfere with the human body’s daily cycle.
All humans have an “inner clock” that called “Circadian Rhythm”. The circadian rhythm is derived from the Latin phrase ‘circa diem’, meaning ‘about a day’, and refers to variations or rhythms with a cycle period of approximately 24 hours. At a high level, people will need enough high intensity, blue-containing light to suppress melatonin during the day, and people need to have low blue levels at low intensity to generate melatonin and regulate the timing of circadian rhythms at night. This is why it is always good to have enough exposure for sunlight during the day to maintain good health and better sleep. Humans are indeed spending more hours indoor than outdoor especially in urban area in the past 200 years.
Daylight and artificial light have great effect on humans, and it affects our hormones, alertness, attention and fatigue, and also determines our body clock and circadian rhythm. With the right light at the right time can influence everything from our sleep to how we feel and perform. The most obvious effect of light on humans, is vision. It enables us to identify brightness, shapes, colors, images, and perceive information and contrast. According to Lighting Wizards principal Stan Walerczyk, the major 5 benefits of HCL are Circadian Rhythms, Improved Productivity, Mood Setting, Visual Acuity, Better energy saving and sustainability.
HCL is indeed getting very popular in the professional lighting industry with one research even claimed the estimated market size to be at about $3.91 Billion by 2024.
What are the key technical drivers for the implementation of HCL?
No. 1 reason is the LED lighting fixture is equipped with high efficacious and lower cost LED with a wide range of color temperatures from 2000K to 6500K. The leds can be at different spectrum and color temperature, and also they can be mixed together( mixing lower CCT 2700K with higher CCT 5000K) to emulate the color temperature of daylight . There are led fixtures which could deliver the specific required color temperatures, spectral power, color, and brightness at a lower cost.
There is also some leds that could directly mimic the sunlight spectrum very well. Seoul semiconductor has released a SunLike LED product with TRI-R Technologies which can produce LED light source with ‘95% reproduction of Sunlight in the visible light spectrum.
The Sunlike LED emulates the sunlight spectrum much better than some conventional LED due to the TRI-R Technologies from Toshiba Materials.
The second major reason is that increasing adoption of real time network lighting control. This gives space users the new capability to control the light brightness and color temperature to match closely with the daylight or special mood setting. In work place it is filled with of different type of tasks . HCL is able to offer the ability of personize and control the lighting to suit their light needs and increase their wellbeing. The control can be either digital( DALI, DMX) or analog protocol(0-10), and it also well enhanced by integrated the sensors that built into lighting control system. The sensors can tell whether the space is occupied and whether there is good daylight or not. The lighting fixtures will then adjust the brightness or color temperature automatically. It can also learn about some users preference with enough data the user interacting with the control system. It could use the tunable white technology to get to the exact color temperature people like and the brightness they prefer. The research shows that the light levels in living environments used by older adults should be increased by at least 50% over those comfortable for younger people. With the great control features in lighting control ,HCL can enhance human performance, comfort, health and wellbeing.
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| LightFlex LED with tunable white lighting in a classroom. Credit: Sunoptics |
HCL is indeed a holistic approach to design a lighting environment to fully take consideration of its occupant task needs and biological needs, to fully maximize the comfort and productivity and wellbeing.
