windows glasses and panes

The most important element on any window efficiency is the type of glass…

Clear single glass

When shopping windows, pay attention to the glass issue. Clear single glass is highly inefficient and causes too much energy to be lost, and too much unwanted sunlight to enter into the home's rooms.

Two and three pane glasses

Demand two panes or three panes of glass for your windows. They will help slow the heat losses. A single-pane glass window has a U-factor of 1,1, which is too high (they allow too much heat to be lost). Modern windows should have a U-factor of less than 0,3. Some manufacturers include plastic films as interior panes.

Argon-Filled Panes

The best windows have argon gas installed between their panes units. Argon is a better insulator than air, making the windows more efficient. The difference between air-filled panes and argon-filled panes is just a detail. But a good window depends on details.

Low-E coating glass

Low-E coating glass is the most common type of glass for boosting the energy efficiency of windows in cold climates. They allow lower values of the U-factor, that is, heat losses will be minimized.

Low E2 glass

Low E2 glasses, also called solar low-E, or spectrally selective glass, are crucial in hot climates. They block unwanted solar gains and contribute to smaller air conditioning bills in summer and hot days.

Visible Transmission (VT)

Controlling glare is also important, in some cases. In North hemisphere countries we want lots of visible light on the north side of the home (in the south hemisphere, on the south side). But we don't want it on the east and west sides of the house. To control that glare and also the heat, we use a glass with a low visible transmission (VT) and a low SHGC.

See, for more information: Windows rating

Impact resistant glasses and tinted glasses

Besides E-low glass and Low E2 glasses, there are also impact-resistant glasses (to improve the safety in areas prone to flying debris or high winds), tinted glasses (to improve privacy or control solar heat gains…) and hydrophilic glass exterior coatings to reduce the frequency of cleaning.

Low E2 glass or darker tinted Glass?

In hot or even in temperate climates, tinted glasses are an alternative to low E2 glasses. They also provide lower solar heat gains. However, they aren't as efficient as Low E2 glasses and yield a decreased outdoor visibility, particularly at night.