Position of the coating

The primary purpose of low emissivity coated glass from the SGG PLANITHERM range is to reduce the amount of heat loss through the glass. This is achieved by reducing the heat exchange between the two/three panes and the cavity space in the double/triple glazed unit. The low-E coating on the glass reduces the amount of radiated heat transfer between the two/three panes. It does this equally well when placed on either glass surface facing into the cavity. To put it another way, the thermal efficiency of an insulating glass unit (or U-value) is not affected by locating the coating on either face 2 or 3. The coating should never be placed on face 1 or 4. However, insulating glass units will differ slightly in their external appearance depending on whether the coating is on face 2 or 3. For this reason it is recommended that where possible the coating is glazed to the same face consistently throughout. This is less important when a low-E coated glass is to be used in conjunction with a textured glass as the slight difference in appearance is less noticeable. This is applicable to both soft and hard-coated low-E glass products.

Extract from document supplied by Saint Gobain Glass UK Ltd.
Weeland Road, Eggborough,
East Riding of Yorkshire
DN14 0FD