Triple-Glazed Windows: Advantages and Disadvantages

Thinking of replacing your windows? Not only will you have to choose among the various frame and sash materials now available (for example, aluminium, PVC, and wood), you’ll also have to make a decision between double or triple glazing.

In the energy efficiency certification program ENERGY STAR, the southern region of the province of Québec is located within their Climate Zone 2. In this zone, windows must be at least double-glazed (simple-glazed windows have, for the most part, fallen into disuse, thanks to their poor energy efficiency performance). That being said, how advantageous is opting for triple-glazed windows, considering their higher cost?

Glazing… Glazing?

But let’s first define what we mean by “glazing”.

Glazing refers to the transparent material used in a window, typically glass.

A double-glazed window generally contains two panes of glass, which are separated by a spacer. The space created can then be filled with air or a special insulating inert gas, such as argon, for example. A fine low-emissivity (Low-E) metallic coating can also be added to limit the sun from coming in during summer while reflecting the heat back in during winter. Note that, within the industry, double or triple glazing is also referred to as insulating glass units (IGUs), sealed glazing, or “thermopane” windows.

Finally, you will have guessed that triple-glazed windows are composed of two air spaces, which can also – both or either – contain an inert gas or a Low-E coating.

Triple-Glazed Windows: Advantages and Disadvantages

Considering this, should we be choosing triple glazing units over double?

Triple glazing offers numerous advantages, the most significant one being – not surprisingly – its outstanding thermal performance. Its temperature coefficient of resistance (R-value) is indeed much higher than double glazing (Source: CAA Québec). This explains in part why triple-glazed products can be up to 50% more efficient than double-glazed (Source: Natural Resources Canada).

A better heat barrier also means an enhanced comfort experience, especially closer to the windows. Another advantage noted is a reduction in indoor condensation, while others also mention greater acoustic insulation for some types of fast traffic noise.

Overall, for colder regions, north-facing windows, or owners wanting to create a more passive house, triple glazing can be an excellent strategic choice.

Triple glazing, whoever, also has its drawbacks. Triple-glazed windows are known to be more expensive. Then, windows made of three glass panes are heavier and require, as such, a sturdier frame and stronger hinges, which implies additional work and cost. Finally, some still report reduced brightness because of the glazing unit’s greater thickness.

So, what is the take-home message? For housing units located in the South of Québec, double-glazed windows made of an insulating spacer, with a Low-E coating, and filled with an inert gas represent, more often than not, the best overall value, in addition to adequately meeting this region’s energy efficiency criteria.

Having said that, we do recommend you consult a window professional to help you fully understand your options and find the best solution for your needs and budget.

Portatec offers a wide selection of high energy efficiency window models. Have their experienced and meticulous team professionally install your windows!

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