In the video below, “Low-E Glass Demonstration,” you’ll find a helpful visual walk-through of how low-emissivity (or low-e) glass works.
First up is a model that shows how low-e glass is used for solar control. Heat lamps in the back of the model simulate infrared light or heat radiation from the sun passing through two panes of glass and touching radiometers—the two glass bulbs—on the other side. The speed at which the vanes spin inside the radiometers indicates the level of heat coming through the glass. The faster the vanes spin, the more solar energy is coming through the glass.
On the left side of the model is a one-inch insulating glass unit (IGU) of two 6-millimeter lites of clear glass. On the right is a one-inch IGU of two 6-millimeter lites of Solarban® 70 glass (formerly Solarban® 70XL glass) by Vitro Glass, a leading solar control low-e glass.
As you’ll see in the video, the radiometer vanes on the clear glass side are spinning very quickly, indicating that the clear glass is blocking very little of the solar radiation, while the vanes on the solar control low-e glass side are spinning very slowly, indicating a great deal of infrared light is being blocked by the glass. In fact, an IGU with Solarban® 70 glass blocks 75% of total solar energy, while the clear glass IGU blocks only 39%.
Glass does three things with solar energy: it reflects, absorbs and transmits parts of the light spectrum. Although we can’t see it, we know that a certain amount of solar energy is being absorbed by the glass. However, we can see solar energy being transmitted and reflected.
In the second model shown in the video, you’ll see what glass does with solar energy. This time, radiometers have been added on the outside of the IGUs to demonstrate the performance of the glass in relation to solar energy on the exterior of a building. Protective panels that shelter the glass from the direct energy of the heat lamps, which represent the sun, have also been added.
On the left side of the model is an IGU of clear/clear glass. The radiometer on the outside is spinning very slowly, indicating not much energy is being reflected by the glass, and the radiometer on the inside is spinning very quickly, indicating that most of the solar energy is being transmitted right through the glass.
On the right side of the model is an IGU of solar control low-e coated glass. The radiometer on the outside of the glass is spinning very quickly, indicating that most of the energy is being reflected by the glass, while the radiometer on the inside of the glass is spinning slowly, indicating that very little energy is being transmitted through the glass.
This demonstrates how solar control low-e glass will help keep solar energy out, therefore enabling more efficient cooling and smaller HVAC systems to be specified, when used on a building in an air conditioning-dominated climate.
For more information about the types of low-e glass and how they work, view the video “How Low-e Glass Works” on the Glass Education Center website. You can also learn more about Vitro’s full line of low-emissivity glass products on our website.
Updated on August 14, 2024
