Have you noticed your home losing heat in winter or overheating during the summer, even with the windows closed? In many Canadian homes, inefficient windows are a major cause of energy loss. If you’re thinking about upgrading, learn more about how to choose the right windows and doors to match both performance and style.
Low-E (low-emissivity) glass is designed to reduce heat transfer, block harmful UV rays, and improve indoor comfort year-round. In this guide, we’ll explain what low-E glass is, how it works, its benefits and drawbacks, and whether it’s worth upgrading your windows.
What Is Low-E Glass and How Does It Work?
The letter “E” is related to emissivity, which indicates the capacity of a given substance to allow heat transfer. Standard window panes are mediocre at trapping heat inside your home.
On the other hand, low-E glass is made with an extremely thin layer of metal or metal oxide coating on the glass surface during the manufacturing stage.
The coating allows light waves to go through without difficulty but prevents the ultraviolet (UV) heat waves, which are longitudinal in nature, from passing through.
In winter, the coating reflects heat generated inside your home back into your rooms. Again, it also prevents most of the escaping heat from getting back outside.
At the same time, it blocks cold outdoor air from transferring its temperature indoors. The result is less heat loss through your windows.
During the summer months, low-E glass works the opposite way. It lets light in but reflects infrared (IR) heat waves, trying to warm up your indoor space. This keeps homes cooler and lowers air conditioning costs. For more details on how energy-efficient windows perform in Canadian climates, Natural Resources Canada provides an overview of ENERGY STAR® certified windows.
The coating regulates temperature flow both ways, depending on the season. This is what makes low-E glass windows a smart upgrade for improving insulation and reducing energy loss, depending on climate, window type, and installation quality.
Types of Low-E Coatings and Which Low-E Coating Glass is Best for the Canadian Climate?
In general, the two types of low-E coatings that are mostly available in the market are hard coat low-E and soft coat low-E. Here’s the definition of these two types:
Hard Coat Low-E
The original low-E coating technology, hard coat, involves applying the metallic oxide layer through a pyrolytic or chemical vapour deposition process.
This process is undertaken at high temperatures within a specialist chamber, where the coating adheres mechanically to the surface of the substrate. The final product is an incredibly durable and scratch-resistant film glass.
Nevertheless, due to the extreme temperatures utilised, the hard coat can be applied only to flat glass sheets and panes. It’s not suitable for more complex bent or odd-shaped glass pieces.
Despite this limitation, hard coats remain popular for windows in harsh environments, like during winter when durability is paramount. It provides reliable insulation, blocking around 70-75% of radiant heat transfer.
Soft Coat Low-E
A newer development is soft coat low-E technology, which applies the insulative layer using physical vapour deposition or sputtering. This type of low-E coat is also known as “Solar Control Low-E Coatings.”
The deposition method occurs at lower temperatures than the hard coat. More importantly, it allows for highly flexible multilayer coatings incorporating various combinations of silver, gold, and dielectric films.
Due to its adaptability, soft coats can be fitted to complex bent glass designs like skylights as well as insulating glass units. It provides increased insulating properties over a hard coat as well, blocking up to 80% of radiant heat transfer.
However, the coating is softer and less scratch-resistant. Over decades of exposure, its insulating layer may degrade slightly more. Since a soft coat of low-E glass is less scratch-resistant, you can use this glass window in cities where storms are less likely to occur.
Advantages of Low-E Glass Windows
Low-E glass windows not only save you money on utility bills but also offer lots of advantages. Here are the Low-E glass benefits
Improved Energy Efficiency
First of all, low-E coating glass windows are an exceptional option to improve energy efficiency in your home. This window can reduce heat loss by up to 30% in winter and lower summer cooling bills by 20-30%.
Many homeowners report noticeable reductions in heating and cooling costs after installing low-E windows, though actual savings vary based on climate, window size, and home insulation. To explore even more advantages of modern windows, check out our detailed post on the benefits of replacing your windows and doors.
Heat Insulation
Besides improved energy efficiency, low-E glass windows can effectively block ultraviolet radiation.
Low-E windows perform so well that they exceed Energy Star standards and are on par with newer wall insulation technologies. Many low-E windows meet or exceed Energy Star® performance standards for energy efficiency.
Triple-pane low-E windows with two argon gas fills can achieve an impressive R-value of R-5, the same as dense fibreglass batts.
Therefore, you can keep your home cooler during summer and also keep the colours of your furniture intact from sun damage.
Noise Reduction
Who wants their family talk to be heard from outside? Similarly, no one wants to live with outer noise coming through windows even after closing them.
If you’re living in a town close to busy roads or airports, you would like to have a window that can reduce the outside noise.
Triple-pane low-E glass windows can block up to 50 decibels, cutting perceived loudness in half for relaxation or work near windows.
Increased Comfort
Winter is knocking on the door in Canada, and you need windows that can keep your home warm and cosy to increase your comfort. Low-E windows keep homes warmer during the winter months through improved insulation.
They use multiple panes of glass separated by airspaces, which are filled with an inert gas like argon for enhanced insulation. The nearly invisible low-E coating between the glass blocks infrared(IR) heat from escaping through the windows, while also blocking cold drafts from entering.
The low-E coating combined with airspaces, gas fill, and tight seals gives low-E windows a higher R-value than single-pane windows. Hence, it significantly reduces heat loss and maintains a cosier indoor temperature. Once your windows are installed, regular care helps maintain their performance. See our window maintenance tips to keep them efficient and lasting longer.
Condensation
Low-E windows reduce condensation by 5-10% compared to regular glass, keeping surfaces drier for at least a few hours longer each morning.
This minimises damage risks from constant moisture that can warp framing and invite mould/mildew growth.
UV Protection
A low-E glass pane blocks over 75% of UVB and UVA rays compared to the 60% blockage of normal glass windows. As a result, it extends fabric and furniture lifetimes by 5-10 years indoors.
Increase Resale Value
Homebuyers are shifting more toward sustainable homes with energy efficiency benefits worldwide. So, having low-E coating windows in your home means taking a step forward in the competition.
Besides, the low-maintenance windows and increased security are two added benefits for homebuyers to consider your deal!
Disadvantages of Low-E Glass Windows
Though there are lots of benefits to having low-E glass windows, you may notice some problems with low-E glass windows, too. Such as:
Loss of Natural Light
While modern low-E coatings are designed to remain mostly clear, some homeowners may notice slightly reduced natural light compared to standard glass, especially in shaded areas.
But imagine what if you live in a shaded area? Wouldn’t it make your home slightly dark during the day?
In that case, you’ll need to keep your windows open to light up your room, which can be an issue for some people living in windy areas.
Cost
The material of the window is more expensive than standard glass because of the additional materials and steps required in manufacturing.
A low-E glass window price ranges between $350 to $850 per window in Canada. However, the energy savings over time can offset the initial cost as well!
FAQs
Here are some frequently asked questions regarding low-E glass:
Q: How do I know if my windows have low-E coating?
Look for an etching or logo on the glass from the manufacturer. You can also have the glass tested for emissivity. Low-E coating is usually a slight blue, grey, or green tint.
Q: Is low-E coating noticeable from inside the home?
High-quality low-E coatings are virtually invisible and don’t darken indoor views. You’ll see clear glass but enjoy improved efficiency. Some older models have a slight tint.
Q: Can low-E windows be cleaned like regular windows?
Yes, low-E coatings are very durable. Use a soft cloth or squeegee with a mild, non-abrasive cleaner and plenty of water.
Q: How long will low-E coating last?
Modern low-E treatments are expected to last the lifetime of the window frame, around 20-30 years, with no visible degradation if maintained properly.
Q: When is the best time to install low-E windows?
You can install low-E glass windows at your home anytime. The benefits of this window make it suitable for year-round use in any weather condition.
Conclusion
So, there you have it, low-E glass is the premium upgrade to your home that will bring in lots of exceptional benefits. This window will make your home peaceful, cosy, and energy-efficient all year round.
However, the installation of a low-E window needs more care and professional hands. If you need a replacement or want to install new low-E windows, professional installation is essential. Book a free low-E window consultation with NUVO to see if this upgrade is right for your home.
