Double Pane Low E Windows U Factor

The u factor measures the thermal performance of the glass in terms of how well it transfers heat into or out of the building.

Double pane low e windows u factor. This figure illustrates the characteristics of a typical double glazed window with a low solar gain low e glass with argon gas fill. Northern north central south central low u factor medium solar heat gain. Double paned windows may have a u factor at or below 0 30. Basic dual pane glass is available on most andersen 200 series windows the perma shield patio door and the narroline gliding patio door.

That means the gases effectively block the air exchange between. The solar heat. Low u factor high solar heat gain. Gases are heavier than air and therefore provide insulation resistance to air.

The u factor for dual pane glass products ranges from 0 49 to 0 51. It provides year round performance and comfort. Low e or low emissivity is an invisible metallic coating on the glass designed to reflect infrared light keeping heat inside in the winter and outside in the summer. Generally speaking windows all have a u factor between 1 3 and 2 and the lower the number the better.

Double pane with low e glass 4. Double pane clear and low e coated glass are rated for energy efficiency based on the u factor solar heat gain factor and visible light transmittance. All of the window components including the frame sash and glass are taken into account in calculating the u factor. Low e windows offer the warmest glass temperatures in winter.

There are a number of factors that impact the energy efficiency of windows and doors. Window type u factor ratings. Low e products andersen s low e4 and low e series of products feature an improved u factor compared with basic. In general the lower the u factor the higher the energy efficiency of the glass.

Double glazed low solar gain low e glass. Here are a few terms to keep in mind. Very low emissivity windows offer the best improvement you can obtain in window insulating performance. Manufacturers have started to incorporate low emittance coatings and gas fills between panes in attempts to further decrease u factors and provide an even more energy efficient product.

High performance double pane windows can have u factors of 0 30 or lower while some triple pane windows can achieve u factors as low as 0 15. Old metal casement window 1 3. Good quality single pane window 1 0. Features a double layer of silver on an inside surface of ig glass.

It also reflects part of ultraviolet light to protect interior furnishings from fading. Triple glazed windows may have a u factor as low as 0 15. Low u factors are most important in heating dominated climates although they are also beneficial in cooling dominated climates. Some triple pane windows may have a u factor as low as 0 15.

The best high performance double pane windows may have a u factor of 0 30 or lower indicating that they are very energy efficient. This coating option provides better protection against radiant heat transfer than single layer metallic low e coatings. Low e windows have u value and emissivity values that range from 0 02 to 0 20 which means that 80 to 98 of the room s heat is reflected back into the room in the winter. These products feature two panes of glass with a pocket of air in between.

As with moderate solar gain low e glass these windows are often referred to as spectrally selective low e glass due to their ability to reduce solar heat gain while retaining high visible transmittance. Good single pane with storm window 6.