The first are the photochromic glasses, which respond directly to an
environmental stimulus (temperature or light) rather like the special
sunglasses which are already available which alter their transmission
factor depending upon the brightness of the ambient light; alternatively
there are the electrochromic glasses designed to respond indirectly by the
application of an electrical current which alters their visual and thermal
characteristics. These glasses are still at the experimental stage, but are
likely to be developed further to a point where they may become viable.
The choice of glazing in a large complex is one of the greatest
importance, having implications both on first cost, and the cost in use of
the project.
WINDOW DETAILS
The Georgian window developed in the eighteenth century satisfied all
the known criteria at the time. It admitted unadulterated daylight, it
provided ventilation when required, and it could be controlled by
internal shutters, providing additional security. The splay at the sides
(and sometimes at the cill as well) together with the careful detailing of
the glazing bars, assisted in balancing the brightness between the inside
of the room and the outside. However it did little for thermal insulation,
and on sunny elevations problems of solar gain and the possibility of
glare, were considered less important at the time.
Windows have developed a long way from this point, from the
standard horizontal or vertical windows set into the side walls of the
majority of residential properties, to the window walls commonly found
in modern office blocks. The Georgian window, however, provides some
lessons which have apparently not been learnt today, mostly to do with
the subtlety of the detailing.
28 Daylighting: Natural Light in Architecture
Extension to Boxmoor church Window with symbolic cross. Compare with
the windows of the original church, having
their own symbolism
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