Clera Windows + Doors Blog

Window Energy Ratings Explained

Energy efficiency has become a major concern for most homeowners, especially when considering options for replacement windows and doors in London. An energy-efficient household keeps the family happy and healthy by enjoying a comfortable temperature all year round. Switching to energy-efficient alternatives is also economical and eco-friendly because it consciously conserves energy and fuel consumption while effectively reducing bills.

To give you a better understanding on how to select the best and most energy-efficient windows, doors, or skylights, we’ll discuss the following topics in this article.

  • How window energy ratings are measured
  • Energy Ratings for windows
  • ENERGY STAR® Certification
  • Practical tips before shopping for energy-efficient windows and doors in London

Let’s delve right in!

How Are Window Energy Ratings Measured

The energy performance ratings for windows and doors in London is tested using the latest Canadian Standards Association (CSA) A440.2 standard. Additionally, some products sold in Canada may also be inspected according to the standards of the National Fenestration Rating Council, which is a non-profit organization based in the United States that provides consumers with energy performance ratings specifically for windows, doors, and skylights.

According to Natural Resources Canada, energy performance ratings are evaluated using the following:

  • U-factor
    U-factor refers to the rate of non-solar heat transfer from warm to cold areas. Basically, it tells you how well a window, door, or skylight insulates. It ranges from 0.25 to 1.25 watts per square metre Kelvin (W/m2K) or in British thermal units per hour per square foot Fahrenheit (Btu/h x sq. ft. x °F). The lower the U-factor, the better.
  • Solar heat gain coefficient (SHGC)
    SHGC numbers illustrate the ratio or the fraction of solar radiation that is transmitted directly to and absorbed by the windows and doors in London and released as heat inside the house. A lower SHGC rating indicates excellent shading ability, which is great during hot summer months because it will block the heat gain from the sun. On the contrary, a high SHGC rating will be effective at keeping the home warm during the cold winter season. Your home’s location, orientation, climate, external shading will all play a pivotal role in choosing the best SHGC you might need.
  • Centre of glass rating
    As the name suggests, this specifically measures the energy efficiency rating of the glass portion of windows, doors, and skylights.
  • Visible transmittance (VT)
    Visible transmittance is an optical criteria that measures a fraction of the amount of visible light that can pass through the glazing material of the window. This is different from SHGC. A higher VT means a window can usher in plenty of natural light. When designed smartly, a home will be able to maximize daylight and conserve energy.

Living room with two vinyl windows

Energy Rating (ER)

If you find the above values complicated, Energy Rating is your best bet. This value suggests the overall performance score of windows and doors. (Skylights not included.) It comes up with a calculation based on the following factors:

  • Solar heat gains
  • Heat loss through frames
  • Spacers and glass
  • And air leakage heat loss

Generally, fixed windows will have a higher Energy Rating compared to those with an opening mechanism, for instance, a tilt-in feature. This is simply because there are less chances of air leakage or heat loss if you cannot open the windows. It is important to emphasize that Energy Ratings accounts only for the window’s energy efficiency performance. It does not consider the quality of materials and therefore have nothing to say about the window’s soundproofing capability or durability.

Living room with blue couch and large vinyl windows

ENERGY STAR® Certification

An ENERGY STAR® certification guarantees that windows and doors in London have successfully passed and gone through stringent testing on energy efficiency performance. This seal of approval are applicable to all fenestration products, including windows, skylights, doors, sidelite, and transoms.

This should be conducted by an accredited third-party laboratory. In Canada, there are only a few agencies that are qualified to perform testing for ENERGY STAR® Certification. This includes:

  • CSA International (CSA)
  • Intertek Testing Services (ITS)
  • Labtest Certifications
  • Quality Auditing Institute Ltd. (QAI)
  • The National Fenestration Rating Council (NFRC)

ENERGY STAR® Certification recognizes that a window company is a leader in energy efficiency and has taken the initiative to do its part for the environment by conserving energy and reducing carbon footprint with its high-quality products.

Clera Windows + Doors is proud to be ENERGY STAR® certified.

Practical Window Shopping Tips

Are you shopping for windows and doors in London as a part of a home improvement project? Follow these tips to help you make smart decisions with your purchases.

  • Identify your climate zone.
    This will help you shop for models that are suitable for the specific conditions in your location.
  • Check the product label.
    Before purchasing windows and doors in London, make sure that they have the ENERGY STAR® symbol, the ENERGY STAR® Climate Zone(s) map (which tells you areas in Canada that the product was certified for), and the energy performance rating verified by the accredited agency.
  • Research about the latest special coatings, glazing technology, or inert gasses.
    These innovations could improve the energy efficiency of your windows and prevent issues with condensation.

    Clera Windows + Doors manufactures its own sealed glass units using Hydraglass 50™ warm edge technology on Super Spacer® platform. We also have Health Smart Windows® that releases lower levels of harmful gasses, such as carbon dioxide (CO2). Our signature glazing technique, on the other hand, is so refined, it allows us to confidently offer a hassle-free, lifetime warranty on all of our sealed glass units.

  • Select a window provider that also offers installation.
    Despite bearing high Energy Ratings or an ENERGY STAR® Certification, poorly installed windows will still be susceptible to draughts, condensation, water and air leakage, and pest infestation.

    At Clera Windows + Doors, we take care of everything, from manufacturing, installation, and after-sales services.

Get the Best Windows and Doors in London

Clera Windows + Doors have the best selection of vinyl windows and doors. For more detailed information about our collection of ENERGY STAR®-certified windows and doors in London, contact us today!

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