Glass has been a major building component for centuries and the basic composition of soda lime glass has changed very little from its conception as blown cylinders flattened out to sheet glass, to today's state-of-the-art float glass.

The major component of soda lime glass is refined silica (sand). Other ingredients such as soda ash, limestone and salt cake are added to lower the melting temperature of silica and promote optical clarity of the finished glass product.

The solar properties of clear glass can be altered in two ways. First the glass can be tinted (coloured) by adding small amounts of metallic oxides to the existing ingredients. For example, the addition of iron oxide produces a green glass. Bronze and grey are produced by the addition of selenium and nickel oxide.

The second method of altering the solar properties of glass, clear or tinted, is to apply a thin metallic coating to the surface of the glass. This type of glass is called coated or reflective glass.

Link to Glass Performance Tables