Double Pane Window Replacement Toronto & GTA – Energy Efficient Glass

Double-pane windows - also called insulated glass units (IGUs) or thermal panes, are the standard for energy-efficient homes and buildings across Ontario. When the sealed unit fails, you lose insulation, clarity, and comfort. OhMyGlass specializes in replacing only the glass unit itself, not the entire window frame, which saves homeowners 60 to 80 percent compared to full window replacement. We serve Toronto and the Greater Toronto Area with a range of IGU options including Low-E coatings and argon gas fills to maximize your home's thermal performance.

How Do Double-Pane Windows Work?

A double-pane window consists of two panes of glass separated by a spacer bar, typically aluminum or a warm-edge composite material. The perimeter is hermetically sealed with a primary seal (usually polyisobutylene) and a secondary structural sealant. The cavity between the panes is filled with dry air or an inert gas such as argon or krypton. This gas-filled cavity acts as an insulating barrier, significantly reducing heat transfer through the window compared to a single pane. The spacer bar also contains a desiccant that absorbs any residual moisture inside the unit to prevent internal condensation.

How Do You Know Your Sealed Unit Has Failed?

Sealed unit failure is one of the most common window problems in the GTA's climate, where wide temperature swings stress the seals over time. Recognizing the signs early prevents further energy loss.

• Fog or haze between the panes that cannot be wiped away from either side - this is moisture that has entered through a broken seal.
• Visible condensation droplets forming between the panes, especially in the morning or during temperature changes.
• White or chalky mineral deposits between the panes - these are left behind as trapped moisture repeatedly evaporates and condenses.
• A noticeable increase in outside noise, drafts, or cold spots near the window - the insulating gas has leaked out.
• Higher heating or cooling bills without other explanation - failed IGUs can increase energy loss through windows significantly.

What Glass Options Are Available for Replacement IGUs?

When we replace your sealed unit, you can choose from several glass and gas options to improve energy performance beyond the original installation.

• Low-E (low-emissivity) coatings - a microscopically thin metallic coating applied to one surface of the glass that reflects infrared heat. Low-E glass can reduce heat loss through the window by 30 to 50 percent compared to uncoated glass.
• Argon gas fill - argon is denser than air and reduces convective heat transfer within the IGU cavity. It improves the window's insulating value by approximately 5 to 15 percent over dry air.
• Krypton gas fill - even denser than argon and used primarily in triple-pane units or where narrower cavities are required. It offers higher performance but at a higher cost.
• ENERGY STAR compliance - the GTA falls within ENERGY STAR Canada Climate Zone 2 (3,500 to 6,000 heating degree-days). Qualifying windows must meet a U-factor of 1.40 W/m²K or lower, or an Energy Rating of 29 or higher.
• Tempered or laminated safety glass - available for IGU replacement where building code or personal safety requires it, such as near doors or at low heights.

How Much Can You Save with IGU-Only Replacement?

Replacing just the insulated glass unit while keeping the existing frame is one of the most cost-effective home improvements available. A full window replacement - frame, hardware, and glass - can cost several hundred to over a thousand dollars per window depending on size and type. An IGU-only replacement uses the same frame and trim, which eliminates the cost of new framing materials, interior and exterior finishing, and the labour to remove and reinstall the full unit. Most IGU replacements are completed in under an hour per window with no damage to your walls, trim, or paint. Contact OhMyGlass for a free on-site assessment to confirm whether your frames are in good condition for IGU-only replacement.