How LoÉ Glass Impacts Comfort in Your Home

What is LoE glass?

When you look at a window, it might seem like glass is just… glass. But in reality, the glass plays a major role in how comfortable your home feels—especially in a Canadian climate.

Modern windows use sealed units—typically argon gas-filled systems made up of multiple panes. These units are designed to control how heat moves in and out of your home. But glass on its own isn’t enough. What really drives performance is something you can’t see: LoE coatings.

LoE also called LowE (low-emissivity) is an ultra-thin metallic coating, typically made with silver. It reflects heat while still allowing most natural light to pass through. In winter, it helps keep heat inside. In summer, it helps reduce heat from the sun.

You’ll often see LoE coatings referred to by numbers like 180, 270, or 366. Generally, as you move from 180 to 270 to 366, the glass becomes more effective at reducing how much solar heat enters your home.

And that’s where the difference between glass options really starts to matter.

Why is my house so hot in the summer?

Many factors can contribute to a home feeling hot in the summer, but one of the biggest contributors is solar heat entering through windows.

Some manufacturers promote glass combinations like clear/clear/180, often emphasizing higher Solar Heat Gain Coefficient (SHGC) values. A higher SHGC means more solar heat enters your home, which can help reduce heating costs in winter. These types of glass packages can still meet energy code requirements, as those requirements consider factors like heat loss, solar heat gain, and air leakage. However, these ratings don’t always reflect how a room will actually feel in direct sunlight.

On a sunny summer day, that added heat doesn’t just warm the space—it builds up. South- and west-facing rooms are the most affected. What starts as a bright room can quickly become too hot to sit in comfortably.

Most homeowners respond by closing their blinds to keep the sun out. While that reduces the effects of sun inside the room, it also traps heat between the glass and the blinds. Over time, this buildup can become intense. This can put stress on the window and lead to issues like:
• Warping or distortion of uPVC frames
• Premature seal failure
• Overheating of interior blinds, including melting, fading, or staining

So while high solar heat gain can look beneficial on paper, it often leads to overheating, reduced comfort, and more reliance on blinds in everyday use.

What type of window glass helps reduce heat in the summer?

The goal isn’t to maximize heat gain—it’s to control it.

That’s where LoE coatings like 270 or 366 come in. These coatings are designed to reduce excess solar heat while still letting in natural light. They help prevent rooms from overheating in the summer without sacrificing brightness.

This is why many well-performing glass combinations include 270 or 366 as part of the system. Whether it’s paired with another coating like 180 or used in a different configuration, the key is that solar heat is being managed—not maximized. The best LoE combinations keep winter heat in while limiting excess heat in the summer.

Key Takeaway

Not all glass performs the same.

Focusing only on solar heat gain or energy ratings can be misleading. In a climate with both cold winters and strong summer sun, too much solar gain can create more problems than it solves.

The right glass strikes a balance—letting light in, keeping heat where you want it in the winter, and preventing your home from overheating in the summer.

At the end of the day, a comfortable home isn’t just about insulation—it’s about control.