What Is a Good ER Rating For Windows?

May 17 2023 Posted By Ontario Window Reviews

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A woman enjoying the sun coming in through her window

Energy Rating (ER) is a score from 0 to 50 that measures energy efficiency. In short, a window ER rating of 34 or higher should do the trick, however, there are many other factors to consider.

In Canada, the National Fenestration Rating Council (NFRC) or Canadian Standards Association (CSA) tests the energy performance of windows, doors, and skylights to align them with the Energy Star standards.

The goal of accredited testing agencies is to enhance the lives of Canadians with high-quality products that bring them long-term comfort at home. That’s why you’ll find them plastered with energy performance rating labels or charts when you go window shopping.

Keep reading to learn more about ER ratings!

Energy Performance Ratings Explained

To calculate an energy performance rating, the NFRC, CSA, and other accredited agencies use the following values:

  • U-Factor / U-Value
  • Solar Heat Gain Coefficient (SHGC)
  • Energy Rating (ER)
  • R-Value
  • Visible Transmittance (VT)
  • Centre-Of-Glass Rating

For this article, let’s focus on the first three.

   1. U-Factor

The U-Factor measures how well a window insulates heat.

Its average values range from 0.20 to 1.20, a scale on which lower numbers represent better efficiency. On the other hand, a high U- Factor value signifies increased heat loss, which is unfavourable during cold seasons in Canada.

   2. Solar Heat Gain Coefficient

SHGC measures how much solar heat passes through a window on a scale of 0.00 to 1.00. Where you live will determine what is desirable here, as lower SHGC-graded windows allow less heat to keep your house cool, whereas higher-graded do the opposite.

   3. ER Rating

Lastly, this represents the balance among U-Factor, SHGC, and air leakage, indicating the overall energy efficiency. As stated earlier, it is measured on a 0 to 50 scale with higher numbers being more desirable.

 Two energy testers write their findings on notepads.

Understanding Window Performance Ratings

Now that you know the three different values involved in achieving desirable energy efficiency, it’s time to learn how to read a window energy performance ratings chart.

This knowledge is necessary since you’re likely to find Energy Star labels as you shop. They’re a reliable window ratings guide and include the following:

No More Climate Zones

You may have heard about climate zones in the past, but Energy Star did away with them in 2020 to make shopping more simple. Dividing Canada into four ‘climate zones’ was confusing for consumers as well as retailers. Now, everything you see in a store with its label has met a country-wide standard, making it appropriate for all homes.

Energy Performance Ratings

You’ll find multiple values on the Energy Star label: U-Factor, SHGC, ER, and VT. When choosing a new window, you only need to look at the U-Factor and ER values since these denote performance and efficiency.

Start with values ranging from 1.22 and below for U-Factor, then see if its ER number is within the scope of 34 and above. If you’re looking for an efficient new window, choose one with an ER of 40 or higher and a maximum U-Factor of 1.05.

Brand Name and Product Information

Moving down the Energy Star label, you’ll find the brand name and information. This is where you can identify the product’s design and materials used in its creation.

When evaluating your options at this stage, consider picking a window that has a double or triple glaze and a Low-E glass coating. These factors are significant in regulating the indoor temperature and reducing energy costs.

A window made out of wood


The bottom contains the certification provided by the Canadian Standards Association (CSA) or other independent third parties that conducted the testing and verification.

Other Things to Consider

Before you say ‘yes’ to a window, check its price tag first and see if the cost fits your budget. If all your choices are expensive, remember that energy-efficient options perform better and are worth every dollar you spend. Simultaneously, installing Energy Star windows makes you eligible for the Green Ontario Fund Rebate Program!

Seek the help of a professional if you’re having difficulty making a decision. Present your current choices, and their expert advice can lead you to the right product to guarantee home energy efficiency!

Searching CSA or NFRC Window Ratings by Manufacturer

So, what is a good ER rating for windows? As we discussed in this article, a window ER rating of 34 or higher is ideal when shopping for new windows.

Fortunately, you’re not the only one trying to make a decision. Based on our customer reviews, these Energy Star Canadian manufacturers meet CSA and NRFA standards:

You can also review our comprehensive chart that compares the top Ontario window brands.

Looking for advice on other aspects of energy-efficient windows or rebate programs? Contact us now for more information.

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