Blog 4. Part 1. Improving Doors & Windows Glass Performance with Low-E Coatings

For Aluminum Clad Wood and uPVC Doors & Windows used in architectural buildings in Dubai to achieve the thermal efficiencies required by current green building regulations, a low emissivity (low-e) glass will need to be used within a glazed sealed unit. Low-e glass has a special coating applied to one of the glass faces; this can be either a ‘hard coat’ or ‘soft coat’ depending on the actual glass coating process used.

Heat energy from the sun is a radiant heat in the infrared spectrum, which is shortwave radiation. This heat energy coming through the glass heats up the building, in addition to any internal heat sources. The heat radiated off the fabric and furnishings is long wave radiation; the low-e glass coating allows most of the visible light to pass through as well as the shortwave heat energy, but blocks long wave energy from passing through. This ensures the heat from outside the building is reflected into the nature and so house remains cool.

In simple terms, Low-E glass has a microscopically thin transparent coating made from tin, silver or zinc, which is applied during the manufacturing process. It is designed to prevent radiant heat loss through the glass by reflecting heat back into the nature. This combined with modern cavities and edge spacer bars for improved thermal performance, help to maintain a stable temperature inside the building by limiting cool loss back out through the glass.