Natural lighting

In humans, more than three-quarters of the information received and processed by the brain comes from the eyes. Orientation in space depends essentially on visual perception of the environment. The precision of our gestures is obtained by the fact that the eye follows them.

For thousands of years

Humans have always depended on the alternation of day and night. The invention of artificial means of lighting has considerably eased the rigors of this subjection. Subject to the constraints of the quality of the work obtained and the cost of implementing these means, it has become possible to live, travel and work outside the hours when natural lighting is sufficient. This has changed social life as a whole, as well as working conditions. In the latter case, it has been possible to free ourselves completely from natural conditions, both by running factories 24 hours a day and by building blind premises.

Before the advent of high-performance artificial lighting techniques, the use of natural light was a necessity, and as such has long stimulated architectural research.

Until the early 20th century, the cost of energy limited the use of artificial lighting. Builders ensured that the number and surface area of windows were sufficient to illuminate the premises to the satisfaction of users.

As energy prices, especially for electricity, fell steadily over the course of the 20th century, builders of industrial premises no longer saw the same interest in them and, in some cases, dispensed with them altogether.

Since the oil crisis of the 1970s, and despite the fact that energy costs have not risen to the point of becoming decisive once again, daylighting has gradually regained importance in architecture. There are three main reasons for this return to favor:

• advances in ergonomics, which have given rise to the notion of the relational role of windows. The importance of working conditions has made the installation of natural lighting a necessity;

• the biological effects of light on humans, which are now better understood. Today, we know that the daily variation in light plays a role in synchronizing our "internal" rhythms with diurnal and seasonal cycles. Light excites the secretion of certain hormones, via a pathway distinct from the visual pathway (suprachiasmatic nucleus);

• awareness of the environmental impacts and risks of electricity generation, whether from nuclear, hydraulic or chemical (combustion) sources.

In the latter case, the primary energy source is generally a hydrocarbon of geological origin (coal, oil, natural gas);...