Low-E insulating glass combines a coated glass lite with an insulating glass unit (IGU) construction. The Low-E coating is made from multiple layers of metals or other compounds. It is designed to transmit visible light while reflecting mid- and long-wave infrared energy, helping the glazing balance daylight with thermal performance.
Coating options
Single-silver Low-E uses one functional silver layer within a coating stack that typically contains five layers in total. It provides the core Low-E functions of light transmission, infrared reflection and improved insulation compared with uncoated architectural glass.
Double-silver Low-E uses two functional silver layers within a coating stack that typically contains nine layers. Its production requires tighter process control than a single-silver coating. For a comparable glass build-up, double-silver Low-E can provide lower emissivity, a lower U-value and a lower shading coefficient than the single-silver option.
Daylight and solar control
All solar-control coatings reduce some visible-light transmission while limiting solar heat. Double-silver Low-E allows the balance to be adjusted further: at the same visible light transmittance it can block more solar heat than single-silver Low-E, and at the same shading coefficient it can admit more visible light. This makes it useful when a facade needs both clear daylight and stronger solar control.
Thermal performance
The lower U-value available from double-silver Low-E reduces heat transfer through the glazing compared with a corresponding single-silver configuration. In an IGU, this supports more stable indoor conditions and can reduce heating and cooling demand. Final coating selection and glass build-up should be matched to the project’s daylight, appearance, solar-control and insulation priorities.