Quebec summers bring 30°C+ days and intense sun. Modern windows can block most of that heat before it ever enters your home — here is what works.
Why Heat Gain Matters in Quebec Homes
Most Quebec homeowners think about windows for winter performance — but summer heat gain is rapidly becoming a bigger issue. Montreal hit 36°C in 2025, and humidity loads pushed indoor temperatures past 30°C in poorly shaded homes.
Windows are responsible for up to 70% of summer cooling loads in homes with poor glazing. Reducing that load is cheaper than upgrading air conditioning.
Understanding the Solar Heat Gain Coefficient
SHGC measures how much of the sun’s heat passes through the glass. A SHGC of 0.25 lets through 25% of solar heat; 0.60 lets through 60%. For Quebec summers, target 0.27–0.35 on west and south-facing windows.
Low-E Coatings That Stop Heat
Solar-control Low-E coatings reflect infrared heat back outside without blocking visible light. The newest 2026 generation (triple-silver Low-E) blocks 78% of infrared while letting through 65% of daylight.
- Choose “solar-control” or “summer-priority” Low-E for west-facing windows
- Combine with argon or krypton gas fill for double benefit
- Pair with triple-pane for maximum performance
Window Tinting vs Coated Glass
Aftermarket tint film cuts heat but voids most window warranties. Factory-applied Low-E is more durable, doesn’t change visible color, and lasts the life of the window.
Strategic Ventilation Choices
Operable styles matter in summer. Casement and awning windows open fully to catch evening breezes; sliders only open 50%. Plan operable units on both sides of the home for cross-ventilation.
Get a Free Heat-Gain Assessment
Our team measures sun exposure per opening and recommends Low-E, SHGC, and operable style per room. Request a free assessment.
Frequently Asked Questions
What SHGC should I target for west-facing windows?
Target 0.25–0.30. West windows receive the strongest afternoon heat in Quebec summers.
Does tinting reduce winter heat gain?
Yes — that’s why factory-applied Low-E is tuned to block summer heat while still allowing some passive solar gain in winter.
Can I add solar control to existing windows?
Aftermarket films work but reduce lifespan. New IGU (insulated glass unit) replacement is cleaner if seals are intact.