Double Glazing for Thermal Insulation

Low e glass 2

What is Low-e Glass?

Glass used in double glazing window for thermal insulation is known as Low E, or low-emissivity glass. It has a transparent metallic coating that works in two ways to economise heating energy. The dual action coating reflects heat back into the room, whilst allowing heat and light from the sun (known as passive solar heat gain) to pass through. Thermal insultion glass should be used on face 2 or 3 of a double glazing unit.

low e glass

U Values

The ‘U’ value of a double glazing window is the measure of its ability to transfer heat – so double glazing windows with the lowest U value are the most efficient insulators against heat loss from a room.

low e glass 1

Solar Heat Gain

The Solar Heat Gain Coefficient (SHGC), which measures a thermal insulation glass’ ability to transmit solar energy into a room, is measured in value from 0 to 1. The SHGC is commonly referred to as the g-value, or solar factor. The higher the g value, the greater a thermal insulation window’s ability to transmit solar heat (see Window Energy Ratings) and thus increase its energy efficiency.

 

Types of Low E Solutions

The most efficient thermal insulation glass use a unique manufacturing process which builds up microscopic layers coating, using a technology known as sputtering, under vacuum conditions. (See online and offline coatings). This advanced process builds up a highly resistant, but imperceptively thin coating which gives it a much clearer appearance than other thermal insulation glass. The coating also allows maximum daylight and heat into the room for optimised solar gain. Some products have been shown to reduce heat loss by 24% more than traditional online coated thermal insulation glass, and by 40% compared to standard double glazing window. Further energy savings can be made by using warm edge ‘thermal break’ spacer bars. These can reduce heat lost around the edge of the window by up to 65%

 

This article quote from http://www.double-glazing-info.com/Choosing-your-windows/Types-of-glass/Low-E-energy-saving-glass