KF 410 uPVC Windows: Passive House Performance in uPVC Inside and Out
Certified by the Passive House Institute and filled with I-tec Insulation, the KF 410 reaches a Uw as low as 0.62 W/m²K, the best figure in Internorm’s uPVC window range. The all-uPVC version delivers that performance in its simplest form, with uPVC on both faces and no cladding to specify.
Certified efficiency without the extra layer
Internorm calls the KF 410 its most versatile window, and in the all-uPVC version it is also the most direct route to Passive House performance in the range. The frame is uPVC inside and outside. With no aluminum shell, what you pay for is insulation, glass and hardware: the parts that decide how warm and quiet the house will be.
That makes it a strong fit for owners building a high-performance home on a disciplined budget, for builders delivering Net-Zero or Passive House projects where every window has to hit a certified number, and for architects who want PHI-certified components behind a classic white elevation. It is one of the most proven Passive House window systems available in Canada.
Compared with the KF 310 uPVC, the KF 410 is deeper at 90 mm, adds I-tec Insulation to the frame and offers the square home pure style in all-uPVC. If you want a coloured exterior or the flush studio look, choose the KF 410 uPVC/Aluminum.
- Passive House, EnerPHit and Net-Zero homes
- White facades, from Georgian-inspired to contemporary
- Multi-unit residential projects that need repeatable, certified performance
Inside the KF 410 profile
The KF 410 shares Internorm’s triple-gasket uPVC platform, then adds the details that take it to certified performance.
I-tec Insulation
Insulating granules are pressed into the frame’s hollow chambers until they are evenly filled. The profile itself loses considerably less heat, with no extra depth and nothing for you to maintain.
Six chambers, 4 mm walls
Six internal chambers and outer walls 4 mm thick give the profile its insulating value and the rigidity to resist warping and cracking through decades of freeze-thaw.
Passive House certified
The all-uPVC KF 410 is certified by the Passive House Institute in Germany, making it a natural choice for Passivhaus and EnerPHit projects where window performance has to be documented, not estimated.
Up to 47 dB quieter
Three continuous gaskets and bonded triple glazing cut outside noise by up to 47 dB, the widest acoustic range among Internorm’s uPVC windows.
Interior finishes
Keep it white, or choose a decor colour or one of thirteen I-tec Decor digital-print surfaces, from light oak to concrete grey, for the inner uPVC face.
Three design styles in all-uPVC
The KF 410 is offered in all four Internorm design styles. Three of them can be built with uPVC on both faces; Internorm supplies the flush studio KF 410 only with external aluminum cladding.
home pure: square-edged
A square-edged frame and sash with simple, straight lines. It suits contemporary homes and modern additions, and gives a white facade a crisp, architectural edge.
home soft: rounded
Rounded edges soften the frame into a harmonious, timeless shape that blends into almost any interior. A safe, elegant choice when the windows should support the architecture rather than lead it.
ambiente: contoured
Contoured, profiled edges recall traditional joinery. Paired with integrated Georgian bars, it suits heritage-style homes and period renovations that still need Passive House-level insulation.
KF 410 uPVC technical data
Best-case values for the all-uPVC KF 410, from the InterHaus data sheet and Internorm’s 2026/27 technical overview.
| Frame material | uPVC inside and outside, six-chamber profile with I-tec Insulation |
|---|---|
| Construction depth | 90 mm |
| Profile width | 76 mm frame + 36.5 mm sash |
| Sightline, frame and sash | 113 mm |
| Sightline, flying mullion (two sashes) | 133 mm |
| Sightline, mullion (two sashes) | 187 mm |
| Thermal insulation (Uw) | As low as 0.62 W/m²K; 0.71 W/m²K with the standard coating |
| Sound reduction | 34–47 dB |
| Security | Up to RC 2, fully concealed locking |
| Gaskets | Three continuous gaskets, light grey external gasket |
| Certification | Passive House Institute certified |
| Design styles in all-uPVC | home pure, home soft, ambiente |
| Expected service life | 40+ years |
Uw depends on window size and glass build-up. For certified projects, our technical team can support your designer or energy consultant with product data.
Built for −20°C, certified for Passive House
Ontario winter temperatures frequently drop below −20°C, and that is when the gap between an ordinary window and a KF 410 becomes obvious. Standard North American windows often sit between 1.2 and 2.0 W/m²K. The KF 410 uPVC reaches 0.62 W/m²K at best and 0.71 W/m²K with the standard glass coating, so even a modest configuration loses a fraction of the heat.
The frame is where many triple-glazed windows lose ground, and it is where I-tec Insulation earns its place. By filling the hollow chambers completely, it raises the insulating value of the profile itself, so the edges of the window stay warm along with the centre of the glass. Warm edges mean no cold strip along the sill and much less chance of condensation or frost where frame meets glass.
InterHaus rates triple-glazed uPVC windows like this as up to twice as effective as the minimum Canadian ENERGY STAR requirement. On a Passive House project, the KF 410’s certification lets your consultant work with verified window data rather than generic assumptions, and for Passive House builds we aim to have a quote back to you within 72 hours.
- Triple glazing with argon or krypton fill
- More than 400 glass combinations, including custom SHGC and Ug values
“My preferred window supplier for any of our projects with ambitious sustainability or indoor comfort goals. They have been easy to work with, and responsive when I need a problem solved. Internorm products have served me well, and these are the best, most reliable suppliers I have found in eastern Canada.”
Openings for every room
Plan each opening around how the room is used. Tilt & turn sashes give secure night-time ventilation and full access for cleaning; tilt-only suits high windows; fixed panes deliver the most glass for the least frame. Combined units, balcony doors and side doors share the same KF 410 profile.
What RC 2 covers, and when to go further
The KF 410 is rated up to resistance class RC 2. Concealed hinges stop the sash from being levered off, the standard locking elements engage octagonal mushroom cams set in the sash, and I-tec Glazing bonds the pane so firmly that it cannot be pushed out of the frame.
Practical extras include lockable handles, a turn lock that allows tilt ventilation but not full opening, laminated safety glass that stays in the frame if broken, and opening sensors that report by radio or cable whether each window is open, tilted or locked.
If a project calls for RC 3, the KF 410 is not the right window. Internorm’s I-tec Secure flap locking, which reaches RC 3, is reserved for the KF 510 and KF 520, and we will tell you plainly which openings justify the step up.
KF 410 uPVC compared
The all-uPVC KF 410 next to its aluminum-clad twin and its closest uPVC siblings.
| KF 410 uPVC | KF 410 uPVC/Alu | KF 310 uPVC | KF 510 uPVC | |
|---|---|---|---|---|
| Exterior face | uPVC | Aluminum | uPVC | uPVC |
| Uw, best value (W/m²K) | 0.62 | 0.62 | 0.69 | 0.63 |
| Uw, standard coating (W/m²K) | 0.71 | 0.71 | 0.76 | 0.71 |
| Sound reduction (dB) | 34–47 | 34–47 | 33–45 | 34–46 |
| Security, up to | RC 2 | RC 2 | RC 2 | RC 3 |
| Construction depth (mm) | 90 | 93 | 71 | 90 |
| Sightline, frame and sash (mm) | 113 | 113 | 107 | 95 |
| I-tec Insulation | Yes | Yes | — | Yes |
| Design styles | home pure, home soft, ambiente | studio, home pure, home soft, ambiente | home soft, ambiente | home pure |
Source: Internorm 2026/27 technical overview for uPVC and uPVC-aluminium windows.
KF 410 uPVC: your questions answered
Both. The KF 410 with uPVC inside and out is certified by the Passive House Institute in Germany, as is the uPVC/aluminum version. The cladding changes the look and the exterior finish, not the thermal performance, so all-uPVC is a sound choice for a Passivhaus or EnerPHit project.
Internorm offers the KF 410 in the flush studio style only with external aluminum cladding. In all-uPVC you can choose home pure, home soft or ambiente, which covers contemporary, transitional and traditional architecture.
If heating performance is the priority, usually yes. The KF 410 improves the best-case Uw from 0.69 to 0.62 W/m²K, adds I-tec Insulation, extends sound reduction to 47 dB and gives you the square home pure style in all-uPVC. The KF 310 keeps a shallower 71 mm depth and a narrower 107 mm sightline, which can matter in a tight renovation opening.
Construction depth is a detail to settle early, especially in renovations and thick, highly insulated walls. Our product specialists, who have an architectural background, review wall sections with your designer or builder and provide installation guidance and supervision so the window sits correctly in the insulation layer.
Unlike fibreglass, which can absorb moisture over time, Internorm’s uPVC is non-porous and fully water-resistant. Compared with regular vinyl it is more rigid and formulated to resist UV, so it does not turn brittle or fade. InterHaus rates the KF 410 for an expected service life of more than 40 years.
Keep exploring
KF 410 uPVC/Aluminum
The same certified window with a powder-coated aluminum exterior and the flush studio style.
Explore
KF 310 uPVC
The compact, value-focused uPVC window with a 71 mm frame.
Explore
KF 510 uPVC
I-tec Secure locking as standard, up to RC 3, with a slim 95 mm sightline.
Explore
Passive House windows
How InterHaus supports Passivhaus, EnerPHit and Net-Zero projects across Canada.
ExploreData sheets & brochures
Dimensions, profile sections, glazing build-ups and performance values — ready for your architect or builder.
Building to Passive House? Get a quote within 72 hours
Send your drawings and window schedule and we will return a KF 410 uPVC specification and quote within 72 hours for Passive House projects. Our product specialists can also coordinate directly with your architect, designer or energy consultant.