Key Takeaways
- Passive house windows must be airtight, well insulated and free of weak points where heat can escape, which is why frame material, glass and seals all matter.
- uPVC suits passive house design because its multi-chamber profiles resist heat flow and the material does not conduct heat the way bare metal does.
- Ultimate Windows uses the Passive House certified Legend system from Deceuninck, with tested double and triple glazed specifications.
- Gasket-sealed window types such as tilt and turn give the compression seal that passive house airtightness depends on.
What Makes a Window Suitable for a Passive House?
A passive house is designed to hold a steady indoor temperature with very little heating or cooling. Windows are the most likely place for that design to fail, because glass and frames lose heat faster than an insulated wall.
A suitable window therefore has to do several jobs at once. It must insulate, seal tightly and keep the glass edge warm enough to limit condensation.
- Low U-value: a lower number means less heat passes through the whole window, frame and glass together.
- Airtight seals: compression gaskets stop draughts, which matter as much as insulation in a sealed building.
- Warm edge spacers: non-metal spacers between the panes reduce heat loss at the glass perimeter.
- Quality glazing: Low-E coatings and an argon fill reduce heat transfer across the gap.
- Careful installation: even a certified window underperforms if the gap between frame and wall is poorly sealed.
Our page on how windows lose and keep heat explains how these features combine in everyday homes.
Why uPVC Works So Well for Passive House Design
Frames make up a meaningful share of a window’s surface, so the frame material has a real effect on performance. uPVC is a natural insulator, and its profiles are built with several internal chambers that trap air and slow heat transfer.
That is a big reason uPVC is used in more than 55% of residential window sales worldwide. For a passive house, the advantages go further than the headline insulation figure.
- Multi-chamber profiles: the internal chambers interrupt the path heat would take through the frame.
- No thermal bridging through the frame: uPVC does not conduct heat the way an uninsulated metal section does.
- Low maintenance: uPVC does not need repainting, which suits a build designed to be low effort to run.
- Long service life: uPVC windows typically last 25 to 30 years, so the performance you pay for is kept for decades.
- Welded corners: frames are welded rather than mechanically joined, which removes joints that could leak air.
If you are weighing materials, our comparison of uPVC versus aluminium windows covers the trade-offs in detail.
The Passive House Certified Legend System
Ultimate Windows manufactures in Wodonga, Victoria, using Deceuninck European-designed profiles. For passive house projects we use the Legend system, which carries Passive House certification.
The two standard specifications below show what the glazing build-up looks like and the U-value each one reaches.
| Specification | Glass build-up | Spacer | U-value |
|---|---|---|---|
| Double glazed | Clear Low-E 4mm, 16mm argon gap, Clear 4mm | Warm edge | 1.7 |
| Triple glazed | Clear Low-E Plus 5mm, 16mm argon, Clear Low-E 5mm, 16mm argon, Clear Low-E 5mm | Warm edge | 1.2 |
U-values are measured in W/m²K, and a lower figure means better insulation. Triple glazing gives the lower number, but double glazing may be enough depending on your climate zone and design. Our page on triple glazed windows in Melbourne helps you decide.
Window Types That Use Gasket Seals
Airtightness depends on how a sash closes against the frame. Passive house projects favour operable windows and doors that press onto a continuous rubber gasket when locked, rather than sliding past a brush seal.
These styles all use gasket sealing within the Legend system:
- Tilt and turn windows: the sash swings in or tilts for ventilation, and multi-point locking pulls it tight against the gasket.
- Tilt and slide windows: a larger sash that tilts for air and then slides, with gasket seals when closed.
- Hinged doors: outward or inward opening doors that compress a seal around the full perimeter.
- Tilt in windows: a simple tilting sash suited to upper floors and cleaning access.
- Lift and slide doors: large sliding doors that lift onto their seals when the handle is closed.
Our tilt and turn windows are the most common choice for passive house builds because they combine ventilation control with a very tight seal.
How to Choose Passive House Windows for Your Build
Window decisions are best made early, while the design is still flexible. Orientation, shading and window size all change how much a given specification needs to do.
- Confirm the performance target your designer or certifier has set for the building.
- Decide where large glazed areas go, since north-facing glass can bring in useful winter sun.
- Choose double or triple glazing based on the climate and the performance target.
- Select operable window types that use gasket seals, and limit fixed units where ventilation is needed.
- Plan the installation details with your builder, including how the frame is positioned in the wall and sealed.
- Book a free measure so frames are made to the exact openings.
One of our customers noted: “They have reduced our power bills & north facing, we have significantly noticed the difference both in summer & winter, including noise reduction.” That experience reflects what good windows can do even outside a certified build.
Why Installation and Support Matter
A certified window only performs as tested when it is fitted properly. Ultimate Windows uses its own in-house install team rather than contractors, so the people who understand the product are the people on site.
- In-house installers: no subcontracted trades fitting your windows.
- Fixed-price quote: a free measure and fixed-price quote with no hidden fees.
- 12-year guarantee: seven years longer than the five years recommended by the AWA.
- Argon gas as standard: included at no extra cost in our double glazed windows.
- Finance available: 100% finance through our Australian finance partner.
You can read more about how we fit windows on our window installation process page.
Frequently Asked Questions
What is a passive house window?
A passive house window is a high performance window that meets strict insulation and airtightness requirements. It combines a thermally efficient frame, multiple glazing layers with Low-E coatings, warm edge spacers and compression seals, so it loses very little heat and avoids draughts.
Are uPVC windows good for passive house projects?
Yes. uPVC frames have multiple air chambers that slow heat transfer, and they are welded at the corners to limit air leaks. Ultimate Windows uses the Passive House certified Legend system, which is built from Deceuninck uPVC profiles designed in Europe.
Do passive house windows have to be triple glazed?
Not always. Triple glazing reaches a lower U-value, 1.2 compared with 1.7 for our double glazed specification, but the right choice depends on your climate, orientation, budget and certification target. Your designer can model both options before you decide, and we can supply specifications for each.
What does warm edge spacer mean?
A warm edge spacer is a non-metal separator between glass panes. Because it conducts less heat than traditional metal spacers, it keeps the edge of the glass warmer, which reduces heat loss and lowers the chance of condensation forming around the perimeter.
Talk to Ultimate Windows About Your Passive House Windows
If you are planning a passive house or a high performance renovation, our team can talk through specifications, window types and timing with you. Book a free measure and fixed-price quote, or call 1300 898 782 to speak with us directly.
