Low-e Glass: How Does It Work?

Windows are a great investment for any house or structure, so whether you are building new, or replacing or upgrading windows in an existing house or building, the benefits of considering Low E glass can literally pay off in a big way.

Low-E glass is a modern invention that can help reduce heat loss in winter and prevent heat from entering in summer.

Low-E glass is essential for homeowners looking for energy efficient windows and smart solutions to energy loss problems. By changing the way that window glass transfers heat, Low-E coatings can help keep homes comfortable while reducing energy costs throughout the year.

What is low-e glass?
Low-E glass, also known as Low E glass, is a type of coated glass that makes windows and doors more energy efficient. Originally designed to hold infrared light in cold climates, they are now a cost-effective option that is effective in several areas.Low E glass has a colourless, ultra-thin, non-toxic coating that minimises the amount of UV light transmitted.Low E glass windows can dramatically improve lighting while reducing heating and cooling costs.

Are Low E glass windows worth it?
Although they may be a slightly larger investment than ordinary glass windows, depending on where you live, Low E glass is very good value for money. They provide you with a beautiful, handsome new window look, with the added benefit of lower energy costs.

The emissivity of a surface is the amount of energy it emits at a particular wavelength, where heat is usually the focus. The thermal emissivity of a material has a value between 0 and 1, with an ideal reflector having an emissivity of 0 and an ideal absorber having an emissivity of 1.

Metals such as silver and aluminium have a thermal emissivity of <0.05, while standard transparent glass has a thermal emissivity of approximately 0.9, making it one of the more emissive materials available. Broken down, standard glass with a thermal emissivity of 0.9 allows 90% of the heat energy to pass through, reflecting the remaining 10%. Clearly, window glass needs some help to reflect the heat back into the room.

This is where low emissivity glass comes into play. Low-E glass is essentially standard clear glass with a microscopically clear coating that reflects more heat than the glass itself, resulting in a composition that has a lower emissivity than standard glass. As a result, glass with a low E coating keeps your home warm by reflecting a higher percentage of heat back into your home and keeps you cooler by reflecting solar heat from outside.

The coating can be either a 'soft coating' - applied offline to the glass in a vacuum chamber at room temperature and sealed in an IGU - or a 'hard coating' - fused to the glass during the production process. -which is fused to the glass surface during the production process. For the purposes of this paper we will focus on soft coatings as they have a lower emissivity and are more commonly used in the UK market.

The coatings used in soft coated low emissivity glass units tend to be low emissivity metallic coatings, such as silver.