What Are ER Ratings And How They Affect Replacement Windows

When shopping for new windows, you’ll want to compare what one company offers over another. But if you just go by what the product consultant says, it may be pretty hard to see the difference – every company says their product is the best.

This is where you may want to rely on the Energy Ratings (ER) system.

A window’s ER rating is calculated on three factors: U-Factor, SHGC and Air Tightness. Lets give these factors a more detailed explanation:

• U-Factor: The U-Factor measures how well a window prevents heat from escaping your home. A lower U-Factor signifies better insulation and greater energy efficiency, crucial for maintaining a comfortable indoor climate and reducing heating costs, especially in colder climates.
• Solar Heat Gain Coefficient (SHGC): SHGC indicates the amount of solar radiation that enters through a window. It is a scale from 0 to 1; windows with a higher SHGC collect more solar heat. Understanding a window’s SHGC helps select windows based on climate control needs. A higher SHGC is beneficial for leveraging solar heat to warm interiors in cooler climates. In comparison, a lower SHGC is preferable in regions with warmer weather conditions to reduce cooling demands.
• Air Tightness: Air tightness in windows refers to preventing air infiltration through the window seals, which can occur when there are gaps or low-quality seals in the window installation. High air tightness in windows is essential for energy efficiency. It prevents unwanted heat loss during cold weather and heat gains during warm weather, contributing to consistent indoor temperatures and lower energy bills.

While these factors are crucial for analysing and calculating the overall energy rating of your new replacement windows, there are a few more things to keep in mind when comparing ER numbers for Canadian windows and doors.

• Fixed windows have a higher Energy Rating than operable ones. There is less air leakage and heat loss in a window you can’t open. Make sure you compare windows from the same category, as numbers in different categories will be greatly different.
• High-performance windows on the market feature different add-ons such us spacers, low-E coating, and gas fill, and may provide positive ER numbers, even for operational windows.

The ER system is a big factor in providing you with the information about the performance of windows. It is a rating based purely on a window’s performance – regardless of what materials it was built with.

One thing the ER value doesn’t take into consideration is the STC or the sound transmission coefficient, as it technically doesn’t contribute to a unit’s performance. But soundproof windows may be of importance to your replacement, so be sure to ask about the STC rating if it isn’t provided.

As of January 2020, homeowners no longer have to consider a Climate zone when shopping for windows that are ENERGY STAR® certified in a particular area. A product in Canada is either ENERGY STAR® certified or not, with a single standard applied nationwide. The minimum ER (energy rating) a window should have to be recognised as energy-efficient (according to Energy Star) is 34.

Another important thing to remember is that no matter how good the replacement windows are, their performance and efficiency can be completely nullified as a result of a bad or improper installation. To make sure your money doesn’t go to waste, make sure the company you decide on has window installers that work to CSA standards and follow all code as necessary.

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