Passive House Windows
for US projects
Passive House lives or dies on the windows. A Passive House window needs an installed whole-window U-value of 0.80 W/(m2K) or lower - about a US U-factor of 0.14 - which takes triple glazing, warm-edge spacers, a deep insulated frame and a warm installation detail. European systems are engineered for exactly that. I source PHI- and Phius-suitable windows in aluminum, uPVC and aluminum-clad wood and deliver them to your job site - DDP in the US, DAP in Canada.
Passive House window requirements: what actually qualifies
The Passive House Institute sets the bar at an installed whole-window U-value of 0.80 W/(m2K) or lower - about a US U-factor of 0.14. The key word is installed: the certifier looks at the whole assembly, including the frame, the glass edge, the warm-edge spacer, and the way the window is set into the wall. A great glass package in a thermally weak frame, or a great window installed cold, will not pass.
That is why this is European territory. Reaching those numbers requires a deep, multi-chamber frame with a wide thermal break, triple glazing with two low-E coatings and argon or krypton fill, warm-edge spacers, and an install that keeps the frame and glass edge above the dew point. European systems have been built to this standard for decades.
| Requirement | Passive House target | Why it matters |
|---|---|---|
| Whole-window U-value, installed (PHI) | 0.80 W/(m2K) or lower - about U-factor 0.14 | The number the certifier checks. It includes the frame, the glass edge and the wall connection, not the glass alone. |
| Phius window targets | Climate-specific | Phius sets the window target by climate zone, checked in the project's energy model. |
| Glazing | Triple, two low-E coatings, argon or krypton fill | Gets the center of glass low enough for the whole window to hit the target. |
| Spacer | Warm-edge (low-conductivity) | Keeps the glass edge warm - an aluminum spacer undoes part of the frame's work. |
| Frame | Deep, insulated: multi-chamber uPVC, wide foam-filled aluminum break, or insulated clad timber | Frame U-value (Uf) is where weaker windows lose the most. |
| Airtightness | Multi-point perimeter locking, continuous gaskets | Supports the blower-door result the whole envelope has to pass. |
| Installation | Warm install detail, over-insulated frame, taped joints | Psi-install is part of the energy model - a cold install can fail a good window. |
The longer version, with the mistakes I see most, is in Passive House windows in the US: what actually qualifies. European data sheets quote Uw in W/(m2K) - the metric U-value to U-factor converter turns it into the US number.
Why European windows hit Passive House numbers
Triple glazing as standard
Two low-E coatings, argon or krypton fill, and warm-edge spacers come standard, not as a costly upgrade.
Deep insulated frames
30-40 mm thermal breaks, multi-chamber profiles, and foam or aerogel fills drive frame U-values European factories have spent decades tuning.
Tilt-and-turn airtightness
Multi-point perimeter sealing delivers the air-tightness a Passive House envelope and blower-door test demand.
Certified components
Some systems carry PHI component certification, so the data drops straight into your PHPP energy model.
Warm install details
Frames are designed for over-insulated, thermal-bridge-free installation into the wall assembly.
Comfort and no condensation
Warm interior surfaces mean no cold draughts and no condensation on the frame - the comfort half of Passive House.
Which windows are best for a Passive House?
The best Passive House windows are the ones that hit your energy model at the lowest cost for the look you want. These are the systems I source most often for low-energy work, in aluminum, uPVC and aluminum-clad wood. The right one depends on your design, climate and PHPP or Phius targets.
| System | Material | Best U-factor (Uw) | Passive House status |
|---|---|---|---|
| Reynaers MasterLine 10 | Aluminum | 0.14 (Uw 0.78) | PHI component certification: confirm exact window variant |
| Aluprof MB-86 AERO | Aluminum | 0.11 (Uw 0.60, Ug 0.5) | Aerogel-insulated frame, under the 0.80 line on paper; certificate checked per project |
| Reynaers MasterLine 8 | Aluminum | 0.16 (Uw 0.88) | Low-energy builds; Passive House certified panel door variant |
| Aluplast Ideal Neo | uPVC | 0.13 (Uw 0.74), triple | Under the 0.80 line with triple glazing; certificate checked per project |
| Clad Passive | Aluminum-clad wood | From approx. 0.11 (converted, not NFRC) | Standard and cold-climate versions; no certificate listed for a supplied unit - checked per project |
U-factors in Btu/(h.ft2.F), best published configuration with triple glazing. Uw in W/(m2K). A converted European value is not an NFRC rating; the tested value for your size and glass comes with the quote, and any certificate is checked for the exact assembly.
Choosing between triple and double glazing? Read the glazing guide. Want timber inside? See aluminum-clad wood windows.
Passive House wood windows: timber and aluminum-clad options
For a Passive House with wood inside, I start with Clad Passive: a timber interior, an aluminum exterior, foamed frame insulation, three gaskets and triple glazing with a warm-edge spacer, with a converted reference from approx. U-factor 0.11 (Uw 0.61 W/(m2K)) - under the 0.14 line on paper. That figure is a conversion of the published European value, not an NFRC rating, and it is not a certificate for the window on your drawing.
Clad Passive comes in a standard and a cold-climate version with different climate and glazing references, so the version, the glass and the installation calculation are confirmed with your energy consultant before ordering. Clad Hidden Sash (from 0.16), Clad Flush (approx. 0.19-0.21) and Timber Lift & Slide (from 0.20) sit above the Passive House window line on paper; Timber Classic and Timber Estate values come with the quote. A large wood lift-and-slide door is a common design choice the energy model then has to carry.
| Line | Construction | U-factor reference | Passive House fit |
|---|---|---|---|
| Clad Passive | Timber inside, aluminum outside; foamed PS frame insulation, 3 gaskets, triple glazing with Swisspacer Ultimate warm-edge spacer | From approx. 0.11 (Uw 0.61), converted | Under the 0.14 line on paper - my starting point for a wood Passive House |
| Clad Hidden Sash | Timber inside, aluminum outside, concealed sash | From 0.16, US catalogue reference | Just above the 0.14 line; low-energy builds, or where the energy model carries it |
| Clad Flush | Timber inside, flush aluminum outside | Approx. 0.19-0.21 (Uw 1.1-1.2), converted | Not a Passive House window; good for code-level energy targets |
| Timber Classic / Timber Estate | Laminated timber inside and out; glazing selected for the project | Not published on the product page | Value for the selected section and glass comes with the quote |
| Timber Lift & Slide | Lift-and-slide door in timber or aluminum-clad timber, large-format triple glazing | From 0.20, US catalogue reference | Above the 0.14 window line - the energy model has to carry a large wood slider |
U-factors in Btu/(h.ft2.F). Converted values come from published European Uw in W/(m2K); US catalogue references are for selected configurations. None is an NFRC rating for a specific order, and the 0.14 line is the PHI installed-window threshold from the table above.
More on the timber build in aluminum-clad wood windows and European wood windows. Wood and clad windows are quoted from drawings, and lead times are confirmed per order.
What do Passive House windows cost?
Passive House windows are quoted per project, but the estimator gives you a budget anchor: about $15 to $25 per square foot supplied for uPVC windows and $45 to $95 for aluminum, before duty and freight, with triple glazing adding about 11-15%. Passive House-grade aluminum such as MasterLine 10 or MB-86 AERO sits at the top of that range or above, and clad timber is quoted from drawings. On a Passive House build the windows carry real load in the energy model, and the spend pays back through a smaller mechanical system. Every US estimate I send is DDP - duty, freight and customs already included; installation is priced locally. Building in Canada? Orders there ship DAP to the site, duty-free under CETA with an origin declaration I prepare - the Canadian path is on European windows for Canadian projects.
Passive House windows - common questions
What makes a window Passive House qualified?+
A Passive House window qualifies on its installed whole-window U-value: 0.80 W/(m2K) or lower under the Passive House Institute (PHI), roughly a US U-factor of 0.14. The whole assembly is judged - triple glazing, warm-edge spacers, a deep insulated frame and a warm installation detail. Great glass in a weak frame, or a good window installed cold, will not pass.
What is the difference between PHI certified and Phius windows?+
PHI certified windows carry a component certificate from the Passive House Institute in Germany, issued for a climate zone with an efficiency class such as phC. Phius, the North American program, sets climate-specific window targets that are checked in the project's energy model. A window can meet either set of numbers without its own certificate - the certifier looks at the data and the installed detail.
What U-factor do I need for Passive House?+
For a Passive House window, aim for an installed whole-window U-factor around 0.14 (Uw 0.80 W/m2K) or better. Premium European systems reach US U-factors of 0.11 to 0.16 with triple glazing - Aluprof MB-86 AERO and Reynaers MasterLine 10 sit at the top of that range. The exact target depends on your climate and the PHPP or Phius energy model. Convert Uw to U-factor.
Aluminum, uPVC or wood for a Passive House?+
All three can reach Passive House numbers. uPVC is often the budget starting point - the Aluplast Ideal Neo catalog value of about U-factor 0.13 Btu/(h ft2 F) with triple glazing is a converted metric assembly figure, not an NFRC rating or a guarantee for every size. High-performance aluminum with a wide, foam-filled thermal break gives slimmer sightlines and architectural finishes. Aluminum-clad wood such as Clad Passive adds a timber interior. I match the material to your design and budget.
Can wood windows meet Passive House standards?+
Yes, on paper, when the frame is built for it. Clad Passive - a timber interior with an aluminum exterior, foamed frame insulation, three gaskets and triple glazing - has a converted reference from approx. U-factor 0.11 (Uw 0.61 W/m2K), under the 0.14 line. It is not an NFRC rating or a certificate for your window, so the version, glass and install calculation are confirmed with your energy consultant. Clad Hidden Sash, Clad Flush and Timber Lift & Slide sit above the line on paper; Timber Classic and Timber Estate values come with the quote. See Clad Passive.
Do Passive House windows need triple glazing?+
In practice, yes. Passive House triple glazed windows - two low-E coatings, argon or krypton fill and a warm-edge spacer - are what gets the center of glass low enough for the whole window to reach 0.80 W/(m2K) installed. For Passive House work I quote triple glazing on every system.
Are there Passive House doors?+
Yes. Reynaers lists a Passive House certified panel door variant of MasterLine 8 at Ud 0.8 W/(m2K), and I check that the certificate covers the exact door, size and glass on your drawing. Large sliding doors are harder: the wood Timber Lift & Slide has a US catalogue reference from U-factor 0.20, above the 0.14 window line, so a big slider is a design choice your energy model has to carry. See MasterLine 8.
How much do Passive House windows cost?+
Passive House windows are quoted per project, but my estimator gives a budget anchor: about $15 to $25 per square foot supplied for uPVC windows and $45 to $95 for aluminum, before duty and freight, with triple glazing adding about 11-15%. Passive House-grade aluminum sits at the top of that range or above. Every US estimate is DDP; installation is priced locally. Run the estimator.
Can you provide the documentation my Passive House consultant needs?+
Yes. I provide the U-factor, SHGC and frame data your PHPP or Phius model and certifier need, and NFRC-rated assembly documentation for code submittal where the configuration supports it. Send me the targets from your energy model and I will match systems that hit them on paper, with the certificate checked for the exact assembly.
Hitting Passive House targets
on your next build?
Send me your window schedule and energy targets - I'll match systems that hit the numbers and have a budget estimate back the same or next working day.