Page 65 - Between light and shade

Light, transparency and reflection

This darkening contributes to the intimacy
of a room and is also useful in increasing its
brightness by means of the reflection of artifi-
cial light. It saves us from the unpleasant “black
mirror” effect 61 produced by glazing under indoor
lighting.

Lighting here is still at least 250 to 500 Lux for
the wealthy (for how much longer?) while it rarely
exceeds 50 to 100 Lux for the poor 62.

Global glass canopies
The fully open crowning oculus at the top of the
43 m diameter half-sphere of the dome of the
Pantheon in Rome (125 A.D.) or the tall stained
glass windows in Gothic cathedrals (48.5 m for the
naves at Beauvais (1225-1272/1500-1548)) enables
natural light to illuminate grand spaces with an
infinite interplay of light and shade.

Oculi and large vertical glazing still form
part of the architectural vocabulary, but the first
large steel frameworks, which appeared from the
second half of the 19th century onwards, enabled
glass roof canopies to be created: covering an
entire edifice, they opened up a new chapter in
the art of building.

61 Unlike a semi-reflective two-way “white” mirror when looking
towards a dark room.

62 During the day, both rich and poor benefit from illuminance
of a maximum of 90000 Lux!
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