What Are Energy Star Windows? Get the Facts

As a homeowner in Canada, you are most likely concerned with lowering your energy costs. And one of the best ways to do so is with Energy Star certified windows? But what are Energy Star Windows and how can they help reduce energy bills?

Every homeowner in Oakville should be aware of the changes that were recently made to Energy Star Windows. Those who wish to upgrade to Energy Star windows should check their local windows company for Energy Star windows cost to help them save up to forty percent on their heating and cooling costs.

Facts About Changes to Energy Star Windows

When choosing Oakville windows and doors, they must adhere to the proper guidelines for the climate in which you reside. Basically, if you live in a colder area, you will need a higher HDD value. The HDD values are as follows:

  • Zone 1: 3499 HDDs and below
  • Zone 2: Between 3501 and 5999 HDDs
  • Zone 3: 6000 HDDs and above

Energy Star has been setting the standard for energy efficiency since the early 1990s. This includes the guidelines for windows ratings in Canada. Any products that adhere to these standards are labeled as such. 

Windows and doors companies in Canada are bound to adhere to these standards, which originated in the United States and were then adopted by the EU and Canada. As well, Canadian window manufacturers must adhere to the requirements set forth by the NAFS (North American Fenestration Standards).  Energy Star Windows are proven to save homeowners a great deal of money on their energy costs while protecting their homes from the harsh Canadian winters.

Energy Star Windows Guidelines: What They Mean

Now that you understand what are energy star windows, read on to see how they are qualified as such.

Visible Transmittance (VT)

VT, or Visible Transmittance, is the amount of light that travels through an object. Higher values of VT equate to more natural light. This is measured in units ranging from 0-100.

Solar Heat Gain Coefficient (SHGC)

SHGC or Solar Heat Gain Coefficient determines the level of solar heat that is obtained via the window pane. As they range from 0 to 100, a rating of 100 means maximum energy efficiency. 

Energy Rating (ER)

ER, or Energy Rating is a combo of solar gain, airtightness, and the U-factor (see below). The ER rating ranges from 0 to 50, with 50 being the most energy-efficient. 


The U-factor determines the process of heat as it transfers from an area that is warm to one which is cold. A higher U-factor indicates that this process occurs faster and is, therefore, higher in energy efficiency. 


The R-factor is used to measure the insulation properties of a window. A higher R-factor indicates stronger energy efficiency. 

Note: Heat gained via natural light does not factor into either the U-factor or the R-factor

Of course, it’s a bit more scientific that, but the above information gives you a brief understanding of how Energy Star windows can help protect your home while lowering your energy costs. This information is beneficial to those who are looking to upgrade or replace their existing windows with ones that are more energy-efficient. 

In addition to choosing Energy Star certified windows, you can opt for double or triple pane windows that have been coated with Low-E (Low-Emissivity coatings) as well as filled with inert gases such as argon or krypton. Together, these factors will keep your home at a comfortable temperature throughout the changing seasons.  

Total Home Windows has a wide selection of Energy Star certified windows and doors. Call us today for a private consultation in your home as well as a free quote on the most energy-efficient windows in the Oakville area.