How to Light

How to Light: What is human-centric lighting?

This question has been answered by Helen Loomes, business development director at Trilux Lighting.

There is an argument that says all lighting is ‘human centric’ because that’s who it’s designed for. As a strictly grammatical definition, that is correct – apart from specialist lighting for plants and animals, all lighting is designed for humans. So something else must be going on.

What we have come to know as human-centric Lighting (HCL) refers specifically to the ways that lighting can be used to support the body’s internal systems. The body’s circadian rhythm is linked to the natural cycle of light and dark, informing the body’s regulators which, in turn, act to ensure that our wakeful and sleep patterns are in tune with the solar day. But more than this, it seems many of our other functions rely on this circadian rhythm to perform at their best – including healing.

The problem for the city dweller is that we are losing that vital connection with the natural rhythms of our world. We spend far more time working indoors than is good for us, and so it’s become necessary to provide artificial stimuli to help keep our bodies tuned to the passage of time. We have come to realise that the ‘human centric’ lighting of the past has never taken into account the non-visual effects that light has on us in our daily lives; in fact, we were not aware of the harm we might have been doing.

HCL has to be a fully-dynamic, 24-hour system for it to work. It’s not simply a piece of technology that can be adjusted at whim. Because we are trying to mimic a natural phenomenon, HCL must display a similar discipline in the way that it produces appropriate illumination into the workplace. And there are other aspects that need to be considered; HCL needs to be part of a biodynamic environment.

The WELL Building Standard offers a new way of looking at how buildings work, supporting a healthy way of being. The latest version of the WELL Standard (v2) identifies 10 drivers that affect the way we function: air, water, nourishment, light, movement, thermal comfort, sound, materials, mind, community. These are the core concepts in creating a healthful building. Lighting alone can have a limited impact, but it works best when it supports, and is supported by, the other nine elements.

A word about lighting design. HCL design does not remove the basic need for the lit space to be a visually attractive and effective environment. The traditional skills of the lighting designer are required as much as ever to ensure that the building employing human-centric lighting is as good as it possibly can be – the basics have to be correct before we even think about adding this next layer. The WELL Standard even has something to say about this: ‘Integrating aesthetically pleasing elements into a space can help building occupants derive a measure of comfort and joy from their surroundings.’ And that is what good lighting is all about.

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