day seen from the interior, as compared to the view through a clear
window.
There are basically three main types of glazing as follows.
- Clear glazing
This can be single sheet, double or triple glazed or alternatively a ‘thick’
glass, but the more sheets or the greater the thickness of glass the more
the daylight will be diminished, although the impression of the colour of
the exterior will still be perceived as natural.
Clear glass whilst allowing a high transmission of daylight, will at the
same time and on certain building fac ̧ades allow a high transmission of
solar radiation. It is this fact that has led to the development of the more
high-tech glasses designed to reduce solar gain, with their consequent
loss of daylight transmission. Other means such as interplane blinds,
located between the panes of glass, may present a solution. These would
only need to to be installed on fac ̧ades subject to solar gain and then only
activated when required.
- Tinted glass
This is of two types: the first where the clear glass is itself modified in
such a way as to produce different radiant heat transmission character-
istics, therefore the thicker the glass the lower the transmission of
daylight, and the greater the control of radiant heat from sunlight.
The second type of glasses are those coated with microscopically thin
layers of metallic oxides which reflect the heat away and out of the
building. These coatings are applied to the inside layer of glass generally
in association with other panes in a sealed double glazed unit as a
protection, since on their own they would be vulnerable to damage.
These coated glasses can be designed to have high daylight transmis-
sion, due to the very thin layer of reflective material; so that they almost
give the appearance of clear glass, and do not suffer from the objections
raised by tinted glasses which reduce the daylight significantly.
Additionally they do not obstruct the view; however they do have cost
implications, and should only be used where the specification demands
it. Highly reflective glasses are available, but need to be used with care to
avoid the danger of glare to other buildings or motorists.
- Miscellaneous glazing
A number of different types of glazing are placed in this category, largely
because they cannot be lumped together into a single category; they
consist of the following:
Patterned glass, wired glass, laminated glasses and glass blocks.Patterned glass
Any number of patterns can be rolled into semi-molten glass, to provide
decorative or diffusing sheets for various purposes, though rarely for
windows, since their capacity for light transmission will be modified.
Wired glass
A similar process is used for the manufacture of wired glass, where a wire
mesh is sandwiched within the thickness of the glass. This used generally
26 Daylighting: Natural Light in Architecture