Double-Pane vs Triple-Pane Windows for Your Ontario Home

A double-pane window has two panes of glass with one sealed space between them. A triple-pane window has three panes and two sealed spaces. Each sealed space adds a layer of insulation, so heat has one more barrier to cross on its way out of your home.

The space between the panes is filled with gas instead of air. In our windows, every double-pane sealed unit is filled with argon and every triple-pane sealed unit is filled with krypton. Both gases are colourless, odourless, and heavier than air, and both slow the transfer of heat through the glass. Krypton is the denser of the two and insulates well in the tighter spaces of a triple-pane unit.

Both types use low-emissivity (Low-E) glass, an invisible metallic coating that reduces UV penetration and reflects heat back into your home in winter and back outside in summer. We apply it as a hard coat while the glass is still molten, which makes it more durable than a coating sprayed on after the glass cools. Glass surfaces are numbered from the outside in, and in Canada the coating belongs on surface three of a double-pane window and surface five of a triple-pane window. Both positions are inside the sealed unit, on the pane closest to your living space.

The panes are held apart by a Super Spacer, a non-metallic warm-edge spacer that lets the glass flex without fracturing. Hot-melt butyl then seals the unit so the gas stays inside.

Are Triple-Pane Windows Worth It in Ontario?

For most Ontario homes, triple-pane windows are worth it for openings that lose the most heat and in rooms where you feel the cold. Natural Resources Canada (NRCan) lists triple glazing as an option for better exterior noise reduction and greater energy savings. With a heating season that runs for months, holding heat in is the job your windows do most of the year.

Triple-pane does the best in these spots.

• North and east-facing windows. NRCan recommends windows with higher insulation values on the north and east sides of a house to reduce heat loss.
• Large picture windows, bay windows and bow windows, where glass makes up more of the wall.
• Rooms where you sit close to the glass, like a reading chair beside the window or a kitchen table by a bay.
• Bedrooms and living rooms that face a busy road.
• Rooms where you have seen condensation or frost on the glass inside your home.
• A home you plan to stay in for many years, where comfort and energy savings have longer to add up.

Triple-pane adds to the investment in each window, so it makes sense to put it where it does the most work. During your free in-home consultation, we look at each opening with you and recommend the glazing that suits it.

Is a Double-Pane Window Good Enough for an Ontario Winter?

Yes, when it is built and installed well. A double-pane window with Low-E glass, argon gas, a warm-edge spacer, and an insulated frame performs far better than the clear-glass, air-filled double-pane windows found in many homes.

The frame carries a lot of that performance. Our UPVC frames and sashes are foam filled for insulation, and the corners are fusion welded into one solid piece, which closes off the joints where older windows tend to leak air.

Double-pane is often a sensible choice for south-facing windows, which take in some free solar warmth on sunny winter days, and for smaller windows where heat loss is less.

Whichever you lean toward, check the ratings on the specific product. To be ENERGY STAR® certified in Canada, a window needs a U-factor of 1.22 W/m²·K or lower, or an Energy Rating of 34 or higher. The number of panes alone does not decide whether a window qualifies. Our guide to window energy ratings explains each number on the label.

Do Triple-Pane Windows Reduce Condensation??

Triple-pane windows can reduce condensation on the inside of the glass because the pane facing your room stays warmer in cold weather. Condensation forms when warm, moist indoor air meets a cold surface, and NRCan lists triple glazing among the window features that reduce it.

Indoor humidity plays a part, too. A home that runs humid in winter can still see condensation on triple-pane glass on the coldest mornings. Our guide to window condensation covers how to bring humidity down.

Condensation between the panes is a separate warning. It means the seal on the sealed unit has failed and moisture is getting into the space between the glass, so the window no longer insulates the way it was designed to. That is a sign the window needs replacing, whether it is double-pane or triple-pane.

Are Triple-Pane Windows Better at Blocking Noise?

Yes. NRCan lists better exterior noise reduction as a benefit of triple glazing, since the third pane and second sealed space give sound one more layer to pass through. You notice the difference most in rooms that face traffic.

Sound also slips through gaps around a window the same way cold air does. Our expert installers ensure your windows are properly sealed to keep those gaps closed.

Do Triple-Pane Windows Let In Less Light?

Slightly. Each added pane and coating lets a little less daylight and solar heat through. If a room already feels dark, compare the visible transmittance (VT) number on the label. A higher VT means more natural light reaches the room.

What Matters More Than the Number of Panes?

You may have read online that triple-pane is mostly an upsell. A third pane performs only as well as the window built around it and the installation that holds it in place. A triple-pane sealed unit in a poorly made frame, or in a window installed out of square, will not deliver what the glass is capable of.

When you compare windows, look at the whole unit.

• UPVC frames and sashes with foam filled chambers, which resist heat transfer, bending, warping and fading.
• Fusion welded and mitred corners, also called a Carpenter’s Finish.
• A warm-edge spacer and a durable seal that keep the sealed unit performing.
• An installation that uses cedar shims to keep each window level, square, and plumb, done by our own expertly trained installers. We do not hire subcontractors.
• A warranty that lasts. Our No Fine Print Warranty covers the product and the installation for as long as you own your home, with no pro-rated terms.

Every window is custom manufactured for your opening in our London, Ontario facility and double-checked by hand before it leaves. You can see how each style is built on our replacement windows page.

How Do You Choose Between Double-Pane and Triple-Pane Windows?

1. Note which direction each window faces. North and east windows gain the most from triple-pane.
2. Mark the rooms where you feel cold near the glass or see condensation on the inside in winter.
3. Flag the rooms where outside noise bothers you, especially bedrooms.
4. Consider size. Large picture, bay and bow windows put more glass in the wall.
5. Think about how long you plan to stay in your home.
6. Compare U-factor, Energy Rating and VT on the label instead of counting panes.
7. Have each opening assessed in person so the recommendation fits your home.

Frequently Asked Questions About Double-Pane and Triple-Pane Windows

Are Triple-Pane Windows Heavier?

Yes. A third pane adds weight to every sash. That matters little on a fixed picture window and more on large windows that open, so the frame and hardware need to be built for the glass they carry.

Do Triple-Pane Windows Help in Summer?

Yes. The layers that slow heat leaving your home in winter also slow heat coming in during summer, and Low-E glass reflects heat back outside.

Find the Right Glazing for Each Window in Your Home

The best place to make this choice is at your home, with someone who can see which way your windows face and how you use each room. Since 1981, we have installed over 500,000 individual windows and doors across Ontario, from London and Kitchener to Barrie and Kingston. Our consultants will show you where triple-pane pays off and where double-pane will serve you well. Book a free in-home consultation.