What Are Window Energy Ratings?

One of the most commonly asked questions about windows is, “What does a window energy rating mean?”

There are lots of resources online to help explain the answer to this question, but often the explanation is lengthy, confusing, and doesn’t take into account your particular situation.

Here is Bavarian’s down-to-earth explanation of everything you need to know about window energy ratings.

What is the purpose of window energy ratings?

The purpose of window energy ratings is to provide you with a number that indicates how well the window will provide energy insulating properties. This means, it will indicate how effectively the window will:

  • Keep the heat inside during the winter
  • Keep the cool air inside during the summer
  • Allow light to pass through the glass
  • Allow air leakage to pass through the glass and frame

What is a U-rating?

U-value is a standardized measurement, used to determine how much heat flows through one area into another area. Or, in simple terms, how fast the heat inside will transfer to the outside (AKA heat loss).

When selecting which windows and doors to purchase and install in your home, you will want to ask about the U-value. The lower the U-value, the slower the heat loss. The lower the U-value, the better.

If you install windows with a low U-value, they will provide better insulation and will help you reduce how often your furnace or AC is running. This can result in reduced energy bills.

If you want to know more about u-ratings, click here for the Government of Canada’s more in-depth description.

Why is a U-rating more important than an ER-rating?

Selecting your windows solely based on an ER-rating doesn’t address issues in Southern Ontario like solar heat gain, which can be intense in the summer months.

It’s generally recommended to select a window with a low U-value and high solar heat shield — as it rejects damaging UV rays. The more solar protection in your window, the more your interior will be protected from fading and damage from ultraviolet rays.

Read more about energy ratings here.

What are Energy Star® windows?

Energy Star® certified windows have been tested by accredited laboratories to ensure that they meet the desired energy performance criteria.

The sticker that you see on your windows will inform you that your windows have been tested and the results have been confirmed by a third-party — so you can rest assured that you are purchasing inspected windows.

There are many kinds of windows that are eligible for Energy Star® certification, including:

  • Windows (hinged, sliding, non-openable, tilt-turn)
  • Skylights (flat-glazed, domed, tubular)
  • Sliding glass doors (single or multiple sliding panels)
  • Hinged doors (single or double leaf*)
  • Folding doors
  • Tilt-turn doors
  • Sidelites
  • Transom windows
  • And more

For more information about Energy Star® rated windows and how to know which windows to install in your home, contact the experts at Bavarian Windows.

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