• Low-E Coatings

    Sealed Units Section

    Low – E

    Document L
    In accordance with EN 673, the Government specify a maximum u-value for double glazed windows of 2.0 W/m²K. At Warm Edge units we can achieve 1.1 W/m²K with a combination of products and techniques, an improvement on the legal requirement of 45%!

    b_image_1Low-E Coatings
    Low-E coatings are microscopically thin, virtually invisible, metal or metallic oxide layers deposited on a sealed unit’s internal surface. They reduce the U-Value by suppressing radiative heat flow.

    The principal mechanism of heat transfer in double glazing is thermal radiation from warm surfaces to cooler surfaces. Coating a glass surface with a Low-E material reflects some of this radiant heat, lowering the total heat flow through the window.

    The Low-E coatings, often based on metallic oxides, are applied to one or more surfaces of insulated glass. These coatings reflect radiant infrared energy, helping to keep radiant heat on the same side of the glass from which it originated.

    Low-E coatings are transparent to visible light, and opaque to Infrared radiation. Different types of Low-E coatings have been designed to allow for high, moderate or low solar gain.

    barsHeat Efficient Windows

    • Radiant heat originating from indoors is reflected back inside, thus keeping heat inside in the winter.
    • Infrared radiation from the sun is reflected away, keeping it cooler inside in the summer.

    Hard / Soft Coated Glass
    Hard coated Low-E products, such as Pilkington K, have been used predominantly in the UK. They are easier to process but have a slight champagne tint which can make white net curtains look dirty. A better U Value can be achieved with a soft coated glass such as Saint Gobain’s Planitherm, which reduces heat loss further. The product is also much clearer with no visible tint.