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Most Efficient criteria for windows and sliding glass doors 2021

Natural Resources Canada (NRCan) recognition criteria for residential windows and sliding glass doors sold in Canada 2021


Windows that meet Version 5 of the ENERGY STAR technical specification for residential windows, doors and skylights sold in Canada.

A window is defined as an assembled unit consisting of a frame/sash component holding one or more pieces of glazing functioning to admit light and/or air into an enclosure and designed for a vertical installation in an external wall of a residential building. This definition also includes all transoms greater than 700 mm (27 in.) in height.

A sliding glass door is defined as a door that contains one or more manually operated panels that slide horizontally within a common frame.


The window or sliding glass door must:


The 2021 Most Efficient designation will be effective from January 1st  to December 31st , 2021. Most Efficient models will be made available on the NRCan website through the energy efficiency ratings search engine for ENERGY STAR certified windows or sliding glass doors.  The Most Efficient logo will be available upon request to qualifying manufacturers and their dealers.  The 2021 Most Efficient designation may be used in association with window and sliding glass door products recognized during this period for as long as the model remains on the market. The 2021 Most Efficient logo must not be applied directly to the window or sliding glass door as a label.

The ENERGY STAR name and symbol are trademarks registered in Canada by the United States Environmental Protection Agency and are administered and promoted by Natural Resources Canada.

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