Page 31 - Between light and shade

Light, transparency and reflection

overall light transmission. However, this kind
of reduction goes hand in hand with an increase
in the time for which artificial lighting is used 8.
Counterintuitively, careful calculation of the
optimum energy trade-off between the dimen-
sions of glazing, insulating performance and
light transmission, often results in large areas
of glazing.

Although large panes of glass were being
produced as early as 1665 by the “Manufac-
ture royale de glaces”, founded by Colbert, for
Louis XIV, their high cost means that their use
was reserved for “special” buildings 9.

By contrast, ordinary window glass, produced
from the middle of the 19th century until 1920
from blown and cut cylinders, was only available
in limited size sheets. In 1925, Gropius again
worked with this traditional limit for the large
sectioned glazed openings of the Bauhaus in
Dessau, while awaiting the worldwide commer-
cial distribution of large panes of drawn glass.
When it arrived, this product allowed for the
widespread use of very large windows and
glazing, which, just like reinforced concrete and

8 It must also be sufficiently evenly distributed, which involves a
large window and ceiling height as well as the building’s depth
being limited.
9 Francis Poty and Jean-Louis Delaet specified sizes of 2.5 m × 1.7

m in 1806 and 8.14 m × 4.2 m in 1889, in their work Charleroi,
pays verrier (Charleroi, the glassmaking city) edited by Centrale
Générale à Charleroi, in 1986.

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