Low E Glass: Importance, Types, Measurement, Advantages & Disadvantages

Low E Glass stands for “low emissivity” glass. Low E windows have glass that has been covered by invisible thin layers of metallic oxide. This coating permits natural light to pass inside the building while bouncing back UV rays and infrared light back out into the environment.

  1. Importance  

UV rays are invisible rays of light released by the sun. UV rays are to blame for fading upholstery, burning skin, and, over the course of numerous years, damaging building materials. Infrared light is heat that warms building at the time the winter. By bouncing back both types of light back out into the environment, low-E coatings keep your building hot in winter and cold in summer.

It is seen that 70% of energy loss in a building is through windows and doors, and 90% of heat loss in windows is through glasses. However, the low E glass reduces energy loss which is why it is used to enhance the work of a passive solar heating home.

  2. Types of Low-E Glass  

The types of low-E glass are divided depending on the type of coating provided. Majorly there are 2 types of coatings, which are:

a. Passive coating 

Passive low-E glass coating is prepared to improve the quantity of heat permitted into a living space and retain warmth in a building.

It decreases the dependence of a building on a heating source. The passive low-E glass is best for east and north-facing windows through which a huge quantity of heat loss is awaited

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b. Solar coating

The solar low-E glass is suggested for the west and south-facing windows where overheating can result in a problem in the summer. The passive low-E glass is suggested for cold climates, whereas solar low-E glass is advised for warm climates.

  3. Measurement of Low E Glass  

According to the Vitro Glass Education Center, there are various details utilized to calculate the advantage of glass with Low-E coatings:

a. Solar Heat Gain Coefficient (SHGC):

This is the fraction of incident solar radiation that is revealed through the window. This can be either straightly passed and absorbed or radiated inside.

b. U-Value:

This is the measurement that is provided to a window depending on how much heat loss it permits.

c. Visible Light Transmittance (VLT):

The calculation of how much visible light proceeds through the glass.

d. Light to Solar Gain:

The ratio between the window’s visible light transmittance and its Solar Gain Coefficient rating.

  4. Advantages of Low E Glass  

The advantages of Low-E Glass are as follows: 

1. Low-E glass can filter out ultraviolet rays that are harmful to skin, hamper furniture quality and distort its color.

2. The coating on low E glass increases its durability and reduces the chance of scratching.

3. The low E glass decreases energy losses by 30-50%, hence the energy efficiency of the building improves dramatically.

4. Therefore, the low-E glass decreases the carbon footprint of the house and prepares it more environmentally friendly.

  5. Disadvantages of Low E Glass  

The disadvantages of Low-E Glass are as follows: 

a.  It is expensive as compared to normal glass.

b. It will trap the heat radiating from objects inward, which may result in overheating of interiors.