Building Construction Handbook, Eighth Edition

(Nancy Kaufman) #1

Double Glazing ~ as its name implies this is where two layers of
glass are used instead of the traditional single layer. Double
glazing can be used to reduce the rate of heat loss through
windows and glazed doors or it can be employed to reduce the
sound transmission through windows. In the context of thermal
insulation this is achieved by having a small air or argon gas filled
space within the range of 6 to 20 mm between the two layers of
glass. The sealed double glazing unit will also prevent internal
misting by condensation. If metal frames are used these should
have a thermal break incorporated in their design. All opening
sashes in a double glazing system should be fitted with adequate
weather seals to reduce the rate of heat loss through the opening
clearance gap.


In the context of sound insulation three factors affect the
performance of double glazing. Firstly good installation to ensure
airtightness, secondly the weight of glass used and thirdly the size
of air space between the layers of glass. The heavier the glass
used the better the sound insulation and the air space needs to be
within the range of 50 to 300 mm. Absorbent lining to the reveals
within the air space will also improve the sound insulation
properties of the system.


Double Glazing

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