July 5, 2024 - Blog Post

Why Get Energy Efficient Windows?

"Energy Efficient and/or Energy Star Certified" windows may sound like a marketing ploy, but they represent more than just a catchy phrase. Developed by Natural Resources Canada (NRCan) as part of the ENERGY STAR program launched in 1992, this initiative aims to promote energy-efficient products and practices, ultimately reducing energy consumption, saving money, and curbing environmental impact by lowering greenhouse gas emissions.

To qualify for Energy Star Certification, window manufacturers must subject their products to third-party testing by laboratories accredited by NRCan. This rigorous evaluation ensures that Canadian consumers can make informed decisions by comparing the energy efficiency of different windows.  The Energy Rating (ER) system helps gauge a window's ability to prevent heat loss, directly contributing to overall energy savings in homes and buildings.  Given that residential windows can account for up to 35% of heat losses in a home, widespread adoption of advanced window technology could potentially reduce total home energy use by 9% and lower greenhouse gas emissions by over 5 megatonnes1.

The ER value serves as a measure of a window's energy performance, indicating its resistance to heat transfer. Higher ER values signify greater energy efficiency, with calculations based on factors such as U-value (heat loss), solar heat gain coefficient (SHGC), and air leakage rate. These factors collectively determine the window's overall energy efficiency rating.

When purchasing windows, consumers should prioritize those bearing the Energy Star Certified symbol, with ratings falling into two categories:

Higher ER numbers correspond to reduced heating energy consumption, leading to lower annual energy bills. Additionally, windows with higher ER values offer better insulation, minimizing the need for heating and cooling while enhancing indoor comfort by reducing drafts and temperature fluctuations2,3.

The top-rated windows, designated as ENERGY STAR Most Efficient (ER of ≥40), are crafted from Cellular PVC, known as RevoCell®, according to NRCan's website. Opting for these Most Efficient Energy Star Certified windows ensures informed decision-making and maximizes energy savings for your home.

ER Less Than 34                                           ER Above 40


1. Paving the Road to 2030: Market Transformation Road Map for Energy Efficient Equipment in the Building Sector.

2. NRCan Publications Archive – Window glazing study at CCHT NRCC-51208 by Armstrong, M.; Burrows, September 2008.

3. NRCan document: Review of Window Energy Rating Procedure in Canada – Final Research Report January 2013.

Thomas Noel, Nordik Windows and Doors

Tag(s): CCI Huronia || Climate Resilient Buildings || Condo Repair Costs || Energy Efficient Windows || Energy saving upgrades