• Dmitriy Kuleshov

Everything you need to know about triple glazed windows: 2020 edition

Updated: Dec 11, 2020


What are triple glazed windows?

Today, dear friends, we’re going to answer your questions about triple glazed windows and why they’re worth the investment.

As with many other things in this world, they come with advantages and disadvantages.

About it, read in today’s post.

Triple glazed windows originated in Sweden as a countermeasure to confront cold weather.

European countries have adapted triple glazed windows as a standard for new buildings; however, Canada and the US are trailing behind Europeans because homeowners are still either not aware of the benefits or not convinced yet that triple glazing outperforms double glazing by all measures.

As mentioned in the database published by the Energy Star®, 86% of all windows are double glazed, 13% are triple glazed, and less than 1% are quadruple glazed.

Builders have long ago abandoned single glazed windows for their poor thermal and energy-efficient properties.

That’s why all newly built houses are fitted with double glazed windows.

Glazing is an industry term meaning glass.


So when you hear the terms double or triple glazing—they mean a window with two or more glass layers with a gas pane between each layer.

Although you need to understand that triple glazing does not have one set of common properties.

In other words, each unit, depending on the manufacturer and built-in components, will vary in performance, energy efficiency and thermal retention.

By combining different glass types, you can achieve the desired levels of light transmission, solar radiant heat transmission and shading coefficient values.


You can find more information about glazing performance by referring to our glazing performance table.

As mentioned above, glazing performance may differ from supplier to supplier and manufacturer to manufacturer.

At Bespoke Windows, we work with eight types of glazing, and these use a combination of glazing, coatings and materials to achieve the U-Value between 0.64 and 2.73 and Solar Heat Gain Coefficient (SHGC) between 0.24 and 0.78—which means that our windows in various combinations meet or exceed industry-level performance.

How does triple glazed windows work?

The following factors impact how effective glazing performs:

- Glass

  • Number of windowpanes

  • Glass thickness

  • Tempering

  • LowE glass

  • Sun-reflecting glass

  • Multifunctional glasses

  • Self-cleaning glasses

  • Heating glass

  • Laminated glass

  • Reinforced glass

- Interlayer

  • Chamber size

  • Filling the chamber with gas

  • Installing blinds in the camera

- Window glass spacer (space bars)

Unlike the double glazed windows, which use the same argon or krypton gasses between the panes of glass, the gas in triple pane windows is injected in both air spaces.

Such a method enables further reinforcement onto an additional pane of glass, which brings up energy rating by 20%.

An additional air gap or cavity between the pane of glass filled with argon or krypton gas makes the air heavier and less conductive, preventing energy from moving through and reducing heat loss.

Another way to increase the energy efficiency of triple-glazed windows and their ability to reduce the transmission of ultraviolet and infrared light and outdoor noise is by applying the Low-E coating.


Low-E coating lowers the transmission of light passing through the window by reflecting harmful UV and infrared light.

There are two types of Low-E coatings:

  1. Passive Low-E coatings - are designed to maximize solar heat gain SHGC into the interior to create passive heating and reduce reliance on artificial heating.

  2. Solar control Low-E coating - is designed to limit the amount of solar heat that passes into the interior to keep the building cooler and reducing energy consumption related to air conditioning.

Low-E coating is produced through a special process called the pyrolytic, which is applied to the glass ribbon while produced on the float line.

The coating then fusses to the hot glass surface and remains translucency. It creates a powerful bond that is more durable than glass film.

The result works on the thermos' principle: it saves the temperature inside by isolating the external environment.

The following is used to measure the Low-E glass performance:


  • Represents the heat flow rate through a window. It's expressed in thermal units, using winter weather conditions of -17°C outside and 21°C inside. The smaller the number, the better the window system is at reducing heat loss.


  • The higher the R-Value, the more efficient the window is in reducing winter heating costs. (This number is the inverse of U-Value.

Solar Heat Gain Coefficient - (SHGC)

  • The amount of solar radiation that enters a building as heat. The lower the number, the better the glazing is at preventing solar heat gain.

Shading Coefficient

  • Measures the total amount of heat passing through the glazing (total solar heat transmittance) compared with a single clear glass. The lower a window’s solar heat gain coefficient or shading coefficient, the less solar heat it transmits, and the greater its shading ability.

Fading Transmission

  • The portion of energy transmitted in a spectral region from 300 to 700 nanometers. This region includes all of the ultraviolet energy and most of the visible spectrum and will give the best representation of relative fading rates. The lower the number, the less prone the carpets and interior furnishings to fading.

The industry benchmarks used to measure U-Value, SHGC and ER for double and triple glazed windows are listed below. Note that double glazed windows tend to have higher solar heat gain due to fewer layers of glass.


Usually, triple glazing with the U-Value of 1.4 or higher is considered poor.

A good U-Value for double glazing is above 1.65; the difference in performance is due to a material that the frame is made of, for example, an aluminum frame which absorbs more heat compared to uPVC or PVC profiles.


Advantages of triple glazed windows?

✓ Superior insulation

  • Top R- and U-values enable the windows to be more efficient in reducing winter heating costs.

✓ Increase energy efficiency

  • Lower your heating bills during the coldest days. One major concern during frigid days is the amount of heat that a house preserves without a continually running furnace. According to the Government of Canada website, around 18 to 35% of heat can be lost through the windows alone. More energy-efficient windows can save you an average of 45% on your energy bills, and if you convert this percentage into a dollar amount, you’ll save between $126 - $523 per year.

✓ Keep interior cooler in summer

  • Fitted with the Low-E coating, triple pane windows can significantly reduce solar heat gain and improve comfort.

✓ Marginal difference in price compared to double glazed windows

  • While the insulating value is improved by 40%, the price differs by a mere 10% from double glazed to triple glazed windows.

✓ Reduce noise

  • From standard triple pane windows to laminated glazed windows, triple pane windows achieve 50% noise reduction.

✓ Enhanced security

  • For example, laminated glass from Cardinal IG offers exceptional security and safety. It’s made of multiple piles of glass with a vinyl interlayer, which allows the glass to hold up a significant impact than other types of glass. It provides a strong barrier against forced entry or extreme wind storms.

✓ Enhanced living comfort (no drafts or cold spots)

  • Tighter air seals, multiple glass panes installed on either the same or variable distances make drafts, and cold spots a problem of the past.

✓ Reduced harmful UV radiation

  • If your windows are not fitted, for instance, with the Cardinal’s IG LowE glazing, then likely your current ones will admit up to 72% of harmful UV radiation and 83% of solar heat, which increase a strain on AC and expose your expensive furniture, flooring, and other things to fade prematurely.

Disadvantages of triple glazed windows?

✗ Weight

  • Weight is the main issue when choosing triple pane windows. Due to the weight of three individual panes of glass, the window sash is exposed to higher impact what poses a problem with weaker materials. The triple pane windows may also pose a problem if your rooms and house have little or no wall insulation.

✗ Number and type of glass reduce light transmission of the window

  • When increasing the number of glass layers, the weight increases and the light transmission reduces.

✗ Triple glazing is more expensive

  • An increased cost of triple pane windows accumulates from multiple factors. One of which is high-quality materials that you fit your window with; because the weight and the width of the window are increased, you may also pay more for labour. However, each company treats projects with triple glazed windows individually. Check on with your contractor about their quotes on triple glazed windows.

So triple or double glazing?

One way or another, the debate over triple or double glazing will remain hot for years to come.

Unless the building code makes triple glazing mandatory, we will see many frustrated homeowners unable to decide on triple or double glazing.

Points for triple glazing:

  • ✅ By paying more for triple glazing, you’re saving on energy bills in the long run.

  • ✅ If you live in a neighbourhood with lots of outside noise.

  • ✅ You want to keep your house warm in winter and cool in summer.

Points against triple glazing:

  • ❌ If you have good double glazing, then you don’t need triple glazing.

  • ❌ If you need improvements only in security and heat preservation, then double glazing will do the job.

  • ❌ If you have a lower budget, then double glazing will be more affordable.

  • ❌ If you live in a moderately old house with weak framing, then you need double glazing, which is less heavy.