Human Centric Lighting (HCL) – Myth or Fact?

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Human beings need natural light: sunlight boosts vitamin D, which is critical for absorbing calcium. It is proven by science, that natural light enhances productivity, increases energy levels and avoids depression. It also directly impacts the amount of sleep a human get, which affects your overall health and well-being. So far the common ground of understanding.
But has this to do with Lighting? Sunlight is free for everyone and in particular in the Middle East, there’s plenty of it. From studies we learn, that on average, people spend 90% of their time indoors.

Humans have evolved to live in harmony with the Earth’s daily light cycle. The way the sunlight changes from morning to night signals your body to behave a certain way. For example, sunlight makes you alert in the morning, while darkness at night makes you sleepy. Before the industrialization, most people lived and worked with the natural light cycle. Today, most people are exposed mainly to artificial light, which is usually static: is too dim during the day and too strong at night, which disrupts the circadian rhythm and increases the risk of disease. Humans need the right light color and intensity at the correct time of day to live life optimally.

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Human Centric Lighting 

Most people are exposed to artificial light the entire day – they need a different way to get health-promoting light. The answer is called Human Centric Lighting or short HCL. With HCL, indoor lighting mimics the natural light cycle and supports the humans circadian rhythm. As a result, HCL encourages productivity during the day and relaxation at night, leading to an improved overall quality of life.
Even though a lot of aspects of lighting and its impact to humans requires further research, it is clear, that HCL has a positive impact on employees, students, patients and residents.

In combination with smart controls based on standards like DALI-2, HCL principles can be applied at the workplace, in schools and homes for the benefit of the people.

HCL -sometimes known as circadian lighting – is a lighting concept that benefits human health and well-being by improving comfort, enhancing mood and boosting productivity of human beings. HCL is achieved by using tuneable LED lights with correlated colour temperatures (CCTs)to simulate sunlight .
What Is Correlated Colour Temperature?
In simple terms, CCT describes how yellow or blue a white LED appears. Colour temperature measurements have been invented in 1848 by William Kelvin, who described the colour changes when he heated a block of carbon. His observations formed the basis for the Kelvin colour temperature scale, used in the Lighting Industry. CCT is expressed in Kelvin (K) temperature units. In the nature, light has the lowest CCT in the early morning hours and the highest in the afternoon. Tuneable LED can be adjusted to various temperatures of white to replicate the CCT of the nature as they change throughout the day. 

What are the Benefits of HCL?

In short, HCL helps individuals to feel more energized and concentrated during the day and more relaxed at night. Selecting the right HCL pattern in a School setting, can support a better learning success and keeping the students focused even during long study days.

Science Opinions

Many studies have been conducted about the impact of light to health and performance. Three of it shall be quoted:

  • Daylight exposure boosts mental health and improves sleep: A study published in the Journal of Clinical Sleep Medicine concludes, that people who worked in a windowless room scored lower in vitality and mental health and sleep than individuals who worked with daylight exposure.
  • Daylight with a view improves workers’ cognitive performance: According to a Building and Environment article, access to sunlight improves performance, working memory and satisfaction in employees. It supports the idea of carefully planned lighting, such as HCL, improves the employee comfort and performance.
  • Cool lighting and computer-related tasks: a study from 2018 concludes, that cool colour temperatures are leading to a significant increase in alertness, when typing and editing tasks. 
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