We are still on the threshold of fully understanding the complex relationship between light and life, but we can now say emphatically, that the function of our entire metabolism is dependent on light.”
Dr. Fritz Albert Popp
In the 70’s a pioneer lighting researcher, Dr John Ott, who worked extensively as a time-lapse photographer with Disney, discovered that good lighting, with a broad span of the visible light spectrum, is essential to photosynthesis in plants. His experiments with plants and later mice revealed that lighting which is deficient in some parts of the full spectrum, adversely affected the full development of a growing plant.
Intrigued by this, Dr Ott turned his research to small animals such as mice and he kept them under fluorescent lighting and allowed them no natural light. Alarmingly, they developed tumours, some even lost their tails, they became very sick and some died. When he put the surviving mice back into natural daylight conditions, their tumours disappeared and they got well again!
Ott discovered that artificial lighting (mainly fluorescent), did not have a balanced spectrum of the colour and was lacking in some parts of the visible lighting spectrum.
His research took him into schools to assess if this deficiency in the quality of light would affect children and their learning in any way. He soon discovered that under poor lighting conditions, lack of concentration, hyperactivity and restlessness were common and that these problems reduced considerably when the lighting was improved and changed to a type with a more balanced spectrum. Much research has been done since then and it is now known that the lens of a child’s eye filters light less efficiently than an adult’s lens, so good lighting with a balanced spectrum is even more important for children.
What to Consider
Comparing products from different suppliers is very difficult unless you have some understanding of what constitutes LED lighting. When you think about computers for instance, it is fair to say that most of them look very similar on the outside, however, we know that the quality of the internal components can vary enormously, producing very different levels of performance and reliabilityThe same is true when it comes to the quality of Solid State lighting
Here are a few things to consider.
1. CRI. Colour Rendering Index
How we see colour is very individual to each person; our eyes, and therefore our visual perception, are not all the same! Age and health will also affect how we see our world.
The ability of the light source to accurately reproduce the true colour of the object being illuminated is known as the colour rendering Index (CRI) of the light source. If the light source does not have a natural balance of all parts of the visible light spectrum, colours will not be faithfully reproduced.
With LED lighting, the quality of the LED chips and encapsulation will determine how good the CRI is. The average for good quality LED lighting nowadays is around 70-80, but CRI up to 90-98 can be achieved with higher quality chips. However, the higher the CRI, the fewer lumens (a measure of how bright a light source is) per watt will be generated..
A higher CRI means a balanced and therefore more natural light, this can have beneficial effects for us both physically and emotionally (mood)
As an example, think how it feels when coming out of a dimly lit place of work, into bright sunshine, and how much better it feels to be outside in bright light. This also explains why conservatories for instance give us a sense of well-being. Natural light with a balanced spectrum enhances our mood.
2. Correlated Colour TemperatureCRI is not to be confused with CCT.
CCT or Correlated Colour Temperature is a specification of the colour appearance of the light emitted by a light source, relating its colour to the colour of light.
For example, the daylight colour temperature varieties through the day. At sunrise and sunset, the CCT is around 3000K, while at noon the CCT is at the highest level – around 5500K or higher. The colour temperature of light has an important effect on a human being. For places where people are gathering to socialise and chill, such as coffee shops, restaurants, and hotel lobbies, a warmer light colour of around 3000K is optimal. The warmer colour of light causes greater relaxation in people. For places where people should be more focused on their work, like in classrooms, offices and conference rooms, the light colour temperature should be cooler – around 4000K. For office workers and factories and warehouses, where good clear light is essential to prevent accidents or mistakes in reading labels for instance, the CCT should be very high – around 5000-5500K.