We're building a passive house in Ottawa - what window specs do I actually need?

For a passive house in Ottawa, you'll need windows that significantly exceed standard ENERGY STAR requirements - typically triple-pane with U-factors around 0.8 W/m²K (0.14 Btu/hr·ft²·°F) or better, which is nearly twice as efficient as standard energy-efficient windows.

Passive House window specifications require extremely low heat transfer rates to meet the rigorous energy standards. In Ottawa's Climate Zone 6, your windows need a U-factor of 0.8 W/m²K or lower, with some projects targeting 0.6 W/m²K for optimal performance. The Solar Heat Gain Coefficient (SHGC) should typically be between 0.45-0.55 to balance winter solar gain with summer overheating prevention. You'll also need exceptional air tightness - the entire building envelope must achieve 0.6 air changes per hour at 50 pascals pressure difference.

Triple-pane construction is mandatory for passive house certification, featuring Low-E coatings on multiple surfaces, krypton or xenon gas fills (which insulate better than argon), and thermally broken frames made from materials like fiberglass, wood, or specialized vinyl. The spacer systems between panes must be warm-edge technology to minimize thermal bridging. Frame materials become critical - standard vinyl frames often can't achieve passive house performance due to thermal bridging.

Installation quality is absolutely crucial for passive house standards. Even the best windows will fail certification if improperly installed. The installation must create a continuous air barrier and thermal bridge-free connection to the wall assembly. This typically requires specialized tapes, gaskets, and installation techniques that go far beyond standard window replacement practices.

Ottawa's climate considerations mean your passive house windows need to handle temperature swings from -30°C to +35°C while maintaining consistent performance. The windows must integrate perfectly with your continuous insulation strategy and vapor barrier system. Most passive house projects in Ottawa use European window manufacturers like Zola, Intus, or Optiwin, though some North American manufacturers like Cascadia Windows are achieving certification.

For a passive house project, you'll need certified passive house components and specialized installation expertise. This goes well beyond standard window replacement and requires contractors experienced with passive house construction standards.