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Spacers are used to maintain a uniform separation between panes of glass in a glazed unit. Conventional spacers are made of hollow aluminum, a material that conducts energy easily and is a significant source of heat loss. Low-conductivity insulating spacers now available are made either from non-metallic materials, a combination of metallic and non-metallic materials (hybrid), or low-conductivity metal materials.

Figure 13

Low-conductivity spacers can improve the thermal performance of a low-e, gas-filled window, door with a window, or skylight by as much as 20 percent. These better spacers also keep the inside glass warmer around the edges, reducing thermal stresses on the glass and reducing the likelihood of condensation in cold weather.