Discoveries in medicine concerning the influence of light on human physiology provoked the creation of the Human Centric Lighting (HCL) approach. Research dedicated to this mainly focuses on optimally matching light parameters to human needs, e.g. increasing concentration, relaxation, etc. However, only a properly designed light source is capable of meeting HCL goals. This paper focuses on the LED luminaire design used in HCL systems. A review of LEDs dedicated to HCL systems was performed. Their advantages and disadvantages are discussed. The Tunable White (TW) design is shown to be the most universal solution for HCL systems because it enables regulation of the colour temperature and spectrum, depending on user needs. However, TW is also the most complex in design. The problems that might arise during TW luminaire design are discussed. Example strategies on how to solve them, focusing on colour mixing and LED arrangement are given. Practical examples of TW luminaire design are also described, each one with a commentary covering encountered issues and their solutions.
