Windows for houses that heat themselves with very little energy.
A Passive House is built so tight and so well insulated that it needs very little heating. Windows are the weak spot of any envelope, so passive houses need windows that are warm on the inside surface, extremely airtight and installed without thermal bridges. Those windows have been standard in Central Europe for years. We bring them to Washington.
What makes a window "Passive House"?
Seattle sits in a mild marine climate (IECC climate zone 4C), so a passive design here can sometimes use slightly less extreme windows than in colder regions. Your energy model (PHPP or WUFI Passive) decides. Phius, the North American program, uses its own criteria; ask your consultant which you're certifying to.
Three systems we use for passive-level projects
| System | Material | U-factor from | Notes | NFRC |
|---|---|---|---|---|
| P-700 | uPVC-steel, central gasket | 0.15 | Lowest cost; aluminum-clad option | Certified |
| MasterLine 10 Elite | Aluminum | 0.15 | Slim aluminum, designed for passive buildings | —* |
| MB-104 Pro | Aluminum | — | Our most insulated aluminum | —* |
U-factor in Btu/h·ft²·°F, best value from product data. *— NFRC rating: ask us for current status for your project.
On a passive house, how the window goes in matters as much as the window.
Installation is half the performance
A great window installed with a thermal bridge around it performs like an average window. On passive projects, talk with us and your designer early about window position in the insulation layer, air sealing and sill support.
Passive House and the Washington State Energy Code
Most Washington homes don't need Passive House windows to meet the WSEC. But high-performance windows make it easier to hit the code's energy credits and keep the rest of the envelope affordable. See Windows for new construction and ADUs. The WSEC is updated regularly; check the edition your permit falls under.
Are your windows Passive House certified?
Do I need triple glazing for a passive house in Seattle?
Can you provide data for PHPP?
Working on a passive project?
Send drawings and energy targets. We'll come back with options and data.