Is the ENERGY STAR criteria for windows, doors, and skylights based on "whole-unit values?"

Yes, the ENERGY STAR criteria for windows, doors, and skylights is based on the whole-unit. Be wary of marketing efforts that tout center-of-glass (COG) data or R-values as opposed to whole-unit data, as this is not a fully accurate representation of the energy efficiency of the product. 

Learn more about ENERGY STAR certified residential windows, doors and skylights at energystar.gov/windows.

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