Human Centric Lighting (HCL), which can also be called human factors in lighting, biophilia or other terms, is becoming the next big step in lighting. It may become more significant than Edison creating the light bulb, because not only can HCL provide good visual lighting quality, energy efficiency and sustainability at a reasonable cost, it can also improve circadian rhythms, short- and long-term alertness, sleep, mood, visual acuity, perception and performance–productivity. HCL provides both visual acuity and biologic benefits. In addition to daylight, specialized fixed spectral content and tunable (dimming and Kelvin or Colour changing) LED products with advanced controls are already available and cost effective and should become standard for business, education, hospital, residential and most other applications much sooner than most people think. Within five years, and maybe as little as three, people will probably look back and wonder how they lived with that old lighting. Remember how it was before you had a smart phone!
The wellbeing and performance–productivity benefits, which may be called 'soft' savings, usually dwarf the typical 'hard' savings of lower electrical bills and reduced maintenance costs. What is very important is that HCL provides both 'hard' and 'soft' savings. HCL shows the real value of lighting and makes lighting much more than a commodity, which is how most people have been considering it for decades. So now is a perfect time for HCL, and it can be considered a wasted opportunity not to.

CCT change using LED light sources can be obtained, mixing warm and cool light by adjusting opposite sides intensity. It also can be obtained mixing some specific colour LED’s, getting better results, but at much higher costs.

Benefits and merit of HCL:
■ Individual, human centred illumination
■ Natural light simulation
■ Better comfort, health, productivity and sleep
■ Supports circadian circle
■ HCL can be implemented as standalone, as well as bigger systems solution

Human Centric Lighting control options: There are two simple ways to control dimming and Kelvin or Colour changing:
■ Using Bluetooth® pre-programed curves
■ Using a smart device like smartphone or a tablet
■ Using a push button (switch dimming)

Two-Colour temperature (2700K or 6500K) light source possible coordinate change of range and deviation from Planckian curve