Inert gas fills ~ argon or krypton. Argon is generally used as it is
the least expensive and more readily available. Where krypton is
used, the air gap need only be half that with argon to achieve a
similar effect. Both gases have a higher insulating value than air
due to their greater density.
Densities (kg/m^3 ):
Air = 1.20
Argon = 1.66
Krypton = 3.49
Argon and krypton also have a lower thermal conductivity than air.
Spacers ~ generally hollow aluminium with a desiccant or drying
agent fill. The filling absorbs the initial moisture present in
between the glass layers. Non-metallic spacers are preferred as
aluminium is an effective heat conductor.
Approximate solar gains with ordinary float glass ~
Single glazing88% 78% 70%Double glazing Triple glazing``Low E'' invisible coatings reduce the solar gain by up to one-
third. Depending on the glass quality and cleanliness, about 10 to
15% of visible light reduction applies for each pane of glass.
Multiple Glazing