What is Low E Glass


Low E glass, also known as low emissivity glass or low-e glass, is specially coated to transmit visible light while reflecting up to 90% of the sun’s heat-producing infrared radiation.

Heat loss through windows and doors accounts for approximately 30% of the heat lost in the entire house. Low-E glass is a modern invention that can help reduce heat loss in the winter and prevent heat entry in the summer.

How is Low E Glass Different from Normal Glass?

The main difference between a  Low E glass and ordinary glass is that Low E glass has a very thin coating applied to one side of the glass. The low-e coating allows visible light to pass through it but reflects infrared radiation, which results in less solar heat gain and greater insulation for your home.

What are the benefits of Low E glass?

  • Reduces energy costs and carbon footprint of the home by preventing heat from penetrating through the glass in Summer while preventing heat loss in winter.
  • Decreases the fading and wear on floors and appliances by blocking out UV rays while still allowing natural sunlight to illuminate the home.

Disadvantages of Low E Glass?

  • Low-e glass can sometimes have a subtle grey haze in certain light conditions. When the glass is exposed to direct sunlight or viewed against a black backdrop, this appears more apparent. This haziness is not readily apparent in most viewing circumstances.
  • Low-e coated glass can also reflect more color, making the glass seem somewhat distinct in color from ordinary glass when viewed side by side.

How Does It Work?

Low-E glass has a reflective coating that reflects short and long-wave infrared radiation. Only visible light passes through low-E coatings. Low emissivity glass inhibits heat transfer and ensures that visible light can pass through the glass in both directions.

Types of Low-E Coatings

    1. Passive Low-E Coatings (Hard-Coat): Passive Low-E coatings are produced via the pyrolytic process, in which a pyrolytic coating is formed. The coating is then applied to the hot glass surface as it’s being produced on the float line, resulting in a strong connection or “hard-coat.” Passive low-e coatings are good for extremely cold climates because they enable some of the sun’s short-wave infrared radiation to pass through and assist heat a home during the winter while reflecting interior long-wave heat energy back inside.
    2. Solar Control Low-E Coatings (Soft-Coat): Solar control Low-E coatings are produced in a vacuum chamber at room temperature utilizing the Magnetron Sputtering Vapor Deposition (MSVD) technique. This coating, known as “soft-coat,” must be sealed within an insulated unit (double glazing). The emissivity of the soft-coat is lower, allowing for better solar control. This process provides the highest level of performance and a nearly invisible coating.

Does Low E Glass Have a Tint?

Low-E coating is a thin metallic coat that is applied to the glass and will not have color variations based on the thickness of the glass. However, it may have a minor, often unnoticeable, reflective and slightly green tint.

What are the Typical Applications of Low-E Glass?

The use of low-e glass in commercial buildings has become common practice because it saves energy and reduces cooling costs for businesses during summer months. It does this by reducing unwanted solar heat gain, thereby making the interior more comfortable for people inside the building and also reducing energy consumption.

In the residential setting, low E glass can help keep homes more comfortable by reducing heat loss and increasing energy efficiency.

Is Low E Glass Expensive?

The installation of Low E glass will typically be more expensive than the installation of clear glass. However, it is less expensive than double glazing.

What Factors Affect the Price of Low E Glass?

The price of low-e glass varies depending upon the manufacturer, type and size of the unit, as well as any special application requirements such as complex shapes or custom sizes. Also note that solar control glazing is often a popular option for new construction and replacement window projects and will be more costly than clear glass on an overall basis.

Alan Tregear

Alan Tregear

Shawn Arkley is a glazier with many years experience providing glass replacement services and currently services the Sydney Eastern Suburbs area.