Insights > Category > Posted: 2023-Jul-20, Updated: 2024-Sep-11

Energy Star (ER) rating - An overall measure of energy efficiency?

Although windows and doors don’t consume energy themselves, they can be a significant source of energy loss. If you're purchasing windows with energy efficiency in mind, the ER helps you make standardized product comparisons.

What is Energy Star?

Energy Star is a government-backed certification program that identifies and promotes energy-efficient products, including windows and doors, to help consumers reduce energy consumption, lower utility bills, and minimize environmental impact.

What is an ER Rating?

The Energy Rating (ER) is a unitless measure used in Canada to assess the overall energy efficiency of a window or door. It combines factors such as heat loss (U-Factor), solar heat gain (SHGC), and air leakage (AL) into a single value.

The higher the ER number, the more energy-efficient the window is, which is important in Ottawa’s cold winters and hot, humid summers.

How is Energy Star certification determined?

The Energy Star certification (based on the CSA A440.2 Standard) measures three key variables to calculate a window's Energy Rating (ER):

The formula is as follows:

ER = (Solar Heat Gain Coefficient × 34) - (U-factor × 37) - (Air Leakage × 0.6)

Solar Heat Gain Coefficient (SHGC) – Measures the amount of solar heat transmitted and absorbed, which is subsequently released inward.
U-Factor (UF) – Measures heat loss through frames, sash, spacers, and glass.
Air Leakage (AL) – Measures the amount of cold or hot air moving through the window or door.

For apples-to-apples comparisons

Energy Star-certified products are tested by authorized, neutral organizations using a standardized procedure to meet strict efficiency specifications, making it easier to compare similar products across different manufacturers. This is especially important in regions like Ottawa, where weather extremes can significantly impact your home’s energy performance.

Save money and reduce your carbon footprint

Energy Star-certified windows are designed with energy efficiency in mind, which can save you money on your energy bills and contribute collectively to reducing carbon emissions. Depending on factors such as your home’s insulation and current windows, upgrading to Energy Star-certified windows can save between 8% and 12% on your energy bills. In fact, windows that qualify for Energy Star’s “Most Efficient” category are up to 40% more efficient than standard windows.

Want to compare windows? Take a look at Energy Star’s most efficient window products to find the best match for your home.

Why it matters in Ottawa

Since Ottawa falls within a northern climate zone, Energy Star certification ensures that windows meet specific standards designed to perform well in our cold winters and moderate summers. Properly rated windows can help maximize home comfort and reduce energy costs year-round.

However, it's also crucial to ensure professional installation. Even the most energy-efficient window won’t perform as expected if it’s not installed properly.

Energy Star summary for Ottawa:

1. The higher the ER rating number, the more energy-efficient the window.
2. Look for windows certified for your climate zone to ensure maximum energy savings.

Need more information?

Want to make sure you're getting the most energy-efficient window for your home? Talk to your local window specialist. They'll help you find the perfect window that maximizes your home comfort and minimizes your energy costs.

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