In recent years window glazing has come on in leaps and bounds as the industry responds to advancements in technology and the ever increasing requirements of the homeowner. Not only do we all want high quality glass, but we also expect energy efficiency and thermal performance. The design of double or triple glazing units can go a long way towards ensuring that our windows meet our needs but the addition of a specific coating on the glass itself such as that used to produced low emissivity (Low-E) glass adds yet another benefit.
What is low-e glass
A low-e coating on your glass will lessen the amount of ultraviolet and infrared light that passes through the glass, while still allowing usual amounts of visible light to enter your home. This coating is a thin and transparent coating that does not affect the look of the glass, however it reflects solar energy and light.
What make low-e glass good for our homes?
Heat is usually absorbed by glass and then radiated out – a process known as emissivity. This absorption and radiation of heat allows for the transfer of that heat from inside your home to the outside – lowering the temperature indoors or alternatively heat from outside passes through and enters your home, heating it up.
When glass has low emissivity that transfer rate is slowed and the insulative properties of that glass are improved. The heat inside the home is reflected back inside, reducing any that passes through the glass. In the summertime the outside heat is reflected and does not enter the house. In this way your home is warmer in the winter and cooler in the summer.
Not only will low-e glass prevent your home from having large changes in temperature, it also prevents your furnishings from being affected by the light and fading or being damaged. Despite this, daylight still enters ensuring our homes feel light and bright.
How is low-e glass made?
There are two types of low-e coatings – sputtered and pyrolytic.
Sputtered are multilayered coatings made from metal oxides including silver. They are incredibly thin and virtually impossible to see, yet they offer great protection against heat entering your home. This coating is less durable than other types of coatings and may well be used inside the sealed double glazing unit to keep it from becoming damaged.
A pyrolytic coating uses a metallic oxide that is bonded to the glass using heat and it is essentially baked into place. This makes it thicker than sputtered coatings but still thin enough to ensure the glass is clear. These coatings are very durable and can be cleaned and exposed in the normal way. These coatings can even be used on single glazed units where they are exposed to the air.
On double glazing units there are potentially four different surfaces that the coating could be applied to. Most double glazing units will have a low-e coating on the inside pane and on the outside pane to offer the summer and winter insulation that is required for UK homes. In environments where heating is usually used indoors a coating of pyrolytic is used, while a silver sputtered coating will be used to reflect sunlight out of the home. In some cases you will have both.
Low-e glass is the perfect choice for UK homes where there is a high degree of difference between summer and winter temperatures. For superior insulation, you should always look for low-e glass on your double glazed units.