Are casement windows better than double-hung windows for energy efficiency?

Casement windows are generally more energy efficient than double-hung windows due to their superior sealing mechanism and single-sash design that eliminates air leakage points.

Casement windows achieve better energy performance because they use compression seals that press tightly against the frame when closed, creating an airtight barrier. The crank mechanism pulls the sash firmly against weatherstripping on all four sides, virtually eliminating air infiltration. Double-hung windows, by contrast, have two movable sashes that create multiple potential leak points where the sashes meet and slide past weatherstripping.

The energy efficiency advantage becomes particularly important in Ottawa's climate. With winter temperatures regularly dropping below -20°C, even small air leaks can significantly impact heating costs and comfort. Casement windows typically achieve air leakage rates of 0.1-0.2 cubic feet per minute per square foot, while double-hung windows often range from 0.2-0.4 CFM/sq ft. This difference can translate to 10-20% better energy performance for casements.

However, the window quality and installation matter more than style alone. A premium double-hung window with triple-pane glass, low-E coating, and argon fill will outperform a basic casement window. For maximum energy efficiency in Ottawa, look for either style with a U-factor of 1.22 or lower to qualify for ENERGY STAR certification and potential Canada Greener Homes Grant rebates up to $5,000.

Consider your specific needs beyond energy efficiency. Casements provide better ventilation control and unobstructed views, while double-hung windows work better with window air conditioners and offer easier cleaning from inside. Both styles can achieve excellent energy performance when properly specified and professionally installed.

For a free assessment of which window style would work best for your Ottawa home's energy efficiency goals, request a consultation from licensed installers through the Ottawa Construction Network.

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