Is natural light being overlooked?

Members of GIF Lumière are campaigning for quantified regulations on the lighting of workplace buildings. Over the coming months, they intend to lobby parliamentarians and public bodies. Two articles of the French Labour Code, R4213-2 and R4223-3, touch briefly on the subject: "buildings must be designed and laid out so that natural light can be used to light workspaces"; "these spaces shall, as far as possible, have sufficient natural light". GIF Lumière laments the absence of a quantified threshold: the only figure on offer is a recommendation from the Institut National de Recherche et de Sécurité, which suggests a minimum daytime natural lighting level of 300 to 400 lux.

Beyond the need for lighting as such, it is natural light that this campaign puts the emphasis on. It acts on our bodies: it reduces the concentration of melatonin in the blood (the hormone that heightens the feeling of tiredness and lowers alertness) and increases the production of cortisol, which has a positive effect on wakefulness and mood.

Bernard Lepage, coordinator of GIF Lumière: "Lighting the workplace naturally from above is a major health and environmental issue that decision-makers must take into account. Our association bases its approach on a simple observation: the use of natural light is too often neglected in France. For many types of premises, however, simple and appropriate solutions exist, such as rooflights, which provide diffuse penetration and an even distribution of natural light throughout a building."

"Its effects (those of natural light) are felt in our internal clock, our sleep, our mood, our cognitive performance... Whereas artificial light acts only on vision, natural light meets biological needs that have only recently been discovered, and remains the best suited to the healthy functioning of the human body." explains Claude Gronfier, doctor of neuroscience and specialist in biological rhythms, a researcher in the Chronobiology Department of Inserm Unit 846 in Bron.