Solar Shading Systems: Design, Performance, and Integrated Photovoltaics by Maria Mandalaki & Theocharis Tsoutsos

Author:Maria Mandalaki & Theocharis Tsoutsos
Language: eng
Format: epub
ISBN: 9783030116170
Publisher: Springer International Publishing

4.2 Visual Comfort Aspects

In the next few paragraphs, we shall describe the relation of the resulting daylight to the perception of space in order to describe the fundamental function of the shading system to affect visual conditions and consequently energy savings.

4.2.1 Relation of Light to Visual Perception

Vision is the ability to gain information through light entering the eyes. Our eyes convert light into electrical signals subsequently processed by the brain. The brain’s interpretation of what the eyes see is called perception.

To accommodate the large range of brightness levels in our environment, the eye adapts by varying the size of the pupil with a muscle called the iris, as well as by changing the sensitivity of the retina. However, it takes about an hour for the eye to make a full adaptation, and, in the meantime, vision is not at its best. Rapid and extreme changes in brightness cause stress and fatigue. However, the eye is very well accustomed to the gradual changes of brightness which are associated with daylighting. A gradual change in environmental brightness is not a liability and might even be considered as an asset because changes are more stimulating than static conditions.

In a previous paragraph, we defined luminance as the absolute value of brightness as measured by a photometer (light meter). A human being, however, judges the brightness of an object by comparing it with the brightness of the immediate surroundings [2].

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