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The Low Down on Low-E Glass

Low-emissivity glass, or low-e glass as it’s more commonly called, is a type of energy-efficient glass that controls heat transfer through windows by using an insulating glaze. In simpler terms, low-e glass helps keep the heat inside your house instead of escaping through your windows to the outside in the winter and in the summer does the opposite.

Both PPG (originally Pittsburgh Plate Glass) and Cardinal Glass introduced low-e glass in 1983. Over the next two decades, low-e coatings that were directly deposited onto the glass captured the vast majority of the market–and they continue to dominate today.

Types of Low-E Glass

There are two types of low-e glass: hard coat and soft coat. Both use a similar process where a microscopically thin layer of metal is applied that helps reflect heat.

Hard coat Low-E glass (pyroletic coated) is manufactured by pouring a thin layer of molten tin onto a sheet of glass while the glass is still slightly molten. The tin actually becomes “welded” to the glass. This process makes it difficult to scratch or remove the tin. While hard-coat low-e is more durable than soft-coat, the emissivity isn’t as low, so these glazings don’t achieve as low a U-factor.

Soft coat Low-E glass (sputter coated) involves the application of silver, zinc or tin to glass in a vacuum. The glass enters a vacuum chamber filled with an inert gas which is electrically charged. The electricity combined with the vacuum allows molecules of metal to sputter onto the glass. The coating is fairly delicate. The soft coat process has the ability to reflect more heat back to the source. Soft coat low-e windows have a higher R-value, which means that they insulate better than hard coat low-e windows.

Low E Glass Benefits

Installing windows containing Low-e glass in energy-efficient double or triple glazed units provides you with many benefits:

  • Improves the energy-efficiency of your home
  • Reduces the amount of energy you use
  • Saves you money on your heating bills

Glass Glossary:

Emissivity: The ability of a material to radiate energy is known as emissivity.

R-Value: a measure of resistance to heat loss.

U-Value:  the rating given to a window based on how much heat loss it allows.

Wakefield Equipment
Wakefield Equipment offers a variety of glass handling equipment designed to improve efficiency and to help achieve an overall goal of maximum speed to manufacture any type of glass. Call our sales department for your customized quote!

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