Low-E Argon Window Facts

Identification

• Low-emittance, or low-e, coatings are applied to windows to make them more energy-efficient, the University of Minnesota Twin Cities’ Center for Sustainable Design Research explains on its Efficient Windows Collective website. Low-e coatings are metal or metallic oxide and “virtually invisible,” the University of Minnesota notes. Argon is a clear, nontoxic and odorless gas that can be applied between two window panes to provide increased thermal insulation.

Types

• Low-e argon windows are available in different glazings to allow for high, moderate or low solar gain. The University of Minnesota reports that high solar gain glazings are better for cold climates. Low solar gain coatings are best suited for warm climates, while moderate solar gain coatings are ideal for year-round use in warm and cool climates. The glazings block heat transfer to decrease the heat flow through a window. The amounts of heat transmitted will vary depending on the glazing. A high-gain low-e window will allow more heat through than a low-gain low-e window.

Benefits

• Low-e argon windows are beneficial because they increase the overall insulating value of windows, notes Kansas State University’s Engineering Extension. Clear glass without a low-e coating has an emissivity rating of around 0.85. With a low-e coating, that rating drops to about 0.15, Kansas State University reports. Thus, the energy efficiency of a low-e treated window is the same as a triple-glazed window but without adding to the weight and size of the window. Argon helps to insulate a home because it transfers less heat than air does.

Considerations

• Kansas State University notes that argon can leak from between a window’s panes. This is typically the result of a seal failure. However, a minor leak -- that is, 5 percent per year -- will not cause a noticeable difference in thermal performance. While the reduced heat transfer of low-e argon windows is ideal during warmer months, Kansas State University notes that it can be a disadvantage in winter -- particularly with south-facing windows. However, the university states that the benefits of low-e windows outweigh any potential heat losses.