The Importance Of Human Centric Lighting In Building Design.

Generally, lighting is designed purely for functionality (i.e., allowing us to see to perform a task or to illuminate an area so it can be safely navigated). However, a human-centric lighting (HCL) installation goes far beyond just functionality, it provides functionality, and it can also provide biological/health benefits.

People are now spending more time indoors whether it be for work or leisure than our ancestors before us. Studies have shown that this can have a negative effect on people’s wellbeing and natural circadian rhythm.  We have a natural circadian rhythm which is in essence our natural 24-hour wake/sleep cycle (which is closely tied into the sun rising and setting).

Studies have shown that a disrupted circadian rhythm can lead to:

  • Increased risk of obesity (disrupted circadian can affect the bodies digestive system)
  • Increased risk of stroke (due to elevated blood pressure)
  • Increased risk of sepsis
  • Increased risk of heart disease
  • Increased risk of depression/mental health issues.


Generally, lighting is designed purely for functionality (i.e., allowing us to see to perform a task or to illuminate an area so it can be safely navigated). However, an HCL installation goes far beyond just functionality-it provides functionality, and it can also provide biological/health benefits! It is more popular in Scandinavian countries where the winters may have periods of months without any sunlight but is beginning to grow in popularity worldwide and the market for HCL is expected to hit $3.91 billion by the year 2024.

"Worldwide, the market for HCL is expected to hit $3.91 billion by the year 2024."

What is HCL? How Does it Work? What are the Benefits?

In order to understand how HCL works a small biology lesson is required. In 2002 the discovery of a third photoreceptor in the human eye essentially gave birth to the idea of HCL. These photoreceptors (known as “Intrinsically Photosensitive Retinal Ganglion Cells (ipRGC’s)) primary function is to signal light for largely subconscious reflexes such as neuroendocrine regulation and synchronizing daily circadian rhythms to the light/dark cycle. The type of light that produces the most effective light is in the “blue” colour region of the visible light spectrum between 400-500nm-which can increase alertness and reactions and decrease sleepiness.

Neuroendocrine Regulation is essentially the regulation (production, suppression, secretion of bodily hormones) and the ones that are particularly of interest in relation to HCL (these hormones are directly linked to the circadian rhythm and well-being) are:

  • Cortisol- known as the stress hormone released by the adrenal glands. This is important for helping your body deal with stressful situations. This hormone plays a vital part in the natural circadian rhythm as it can help control blood sugar levels, regulate metabolism, reduce inflammation, and assist with memory formation.
  • Melatonin- Often referred to as the sleep hormone (also known as the darkness hormone), it is primarily released by the pineal glands. It is produced in the evening and peaks around midnight. Melatonin actively promotes healthy sleep (helping the body wind down) and helps enforce the body’s natural circadian rhythm
  • Serotonin- referred to as “the happy hormone”. It can impact various bodily functions from emotions to motor skills. It can reduce depression, regulate anxiety, and enhance sleep.
  • Dopamine- this hormone is responsible for pleasure, alertness & muscle coordination.


As can be seen from the graphic above, Attention spans peak when cortisol is at its highest level and attention spans are at their lowest when melatonin levels are at their peak. Cortisol production is linked to “cool white” light and melatonin production is linked to “warm white” light. The most beneficial operation of an HCL installation is a cool white light in the mornings and warm white light in the evenings. With a DALI lighting control system, the HCL installation could be configured for various starting times/shifts and offers more flexibility to the installation. The difference between cool white and warm white light can be seen in the graphic below.

In essence, HCL is the art of artificially mimicking the colour temperature of the sun as the day progresses. HCL operates using tunable white luminaires (luminaires that can change their colour temperature as required) combined with a DALI lighting control system. The benefits from HCL according to lighting manufacturer Panasonic include:

  • Maximized concentration and energy
  • Improved work performance and productivity
  • Increased motivation & commitment
  • Improved circadian rhythm & quality of sleep
  • Increased emotional stability & lowered rates of depression.


Human-centric lighting is lighting that changes colour temperature as required to gain biological benefits. Human Centric Lighting is a technology that is growing in popularity worldwide as LED technology becomes more efficient and cheaper. It has applications across various sectors such as offices, educational buildings, healthcare premises and control rooms within data centres and pharmaceutical plants. Various building standards are recognizing the importance of the interaction between the end-user and the built environment, and the WELL building standard now offers credits for human-centric lighting installations.

If you’d be interested in a human-centric lighting installation for your project or if you’d like to find out more about human-centric lighting then please contact our Electrical Engineer Aidan Drennan.