Most Quebec homeowners obsess over U-factor for winter. SHGC is just as important — and few quotes even mention it.
What is SHGC?
SHGC (Solar Heat Gain Coefficient) is a number between 0 and 1. It tells you what fraction of solar energy hitting the window passes through as heat. Lower numbers = less heat, which is good for hot weather and cooling-dominated rooms.
U-Factor vs SHGC: Different Jobs
U-factor measures heat lost through the glass when there is no sun. SHGC measures heat gained when the sun is shining. Both matter in Quebec, where you have both extreme winters AND increasingly hot summers.
Choose Different SHGC by Window Orientation
- North-facing: SHGC 0.40–0.50 (any heat gain is welcome in winter)
- East-facing: SHGC 0.30–0.40 (morning sun is manageable)
- South-facing: SHGC 0.35–0.45 (passive winter gain useful, summer overhangs help)
- West-facing: SHGC 0.25–0.30 (afternoon sun is brutal)
How to Specify SHGC on Your Quote
Most installers default to a single glass package across the whole home. Insist on per-orientation specification — the cost difference is marginal but the comfort impact is real.
Frequently Asked Questions
Does ENERGY STAR specify a target SHGC?
Yes — for Zone D (Montreal area) ENERGY STAR allows SHGC up to 0.32 for high-performance certification.
Can I have different SHGC values per window?
Yes — reputable manufacturers offer multiple glass packages on the same quote.
Does triple-pane always lower SHGC?
Usually yes, especially with two Low-E coatings (one per cavity).