Where should the Pilkington K Glass pane be positioned in my double glazing?

Pilkington K Glass™ is a low emissivity glass, specifically designed to enhance the thermal insulation of insulating units. It achieves this by being positioned in the insulating unit with the Pilkington K Glass™ coating on a surface facing the cavity. In a double glazing unit, counting the surfaces from the exterior of the building, The Pilkington K Glass™ coating should be on surface 2 (the inner surface of the outer pane) or surface 3 (the cavity surface of the inner pane). Pilkington K Glass™ performs the function of enhancing the thermal insulation (reducing the U value) equally well whether it is positioned on surface 2 or surface 3. However, with any coated glass, there may be slight optical effects when the coating is present. These optical effects are reduced when Pilkington K Glass™ is used with the coating on surface 3, rather than surface 2. General advice is that the preferred location of the Pilkington K Glass™ coating is on surface 3 of the unit, but if the glass types ...  more