VEKA Therm-82 & Schüco MB-104 Passive:
The US Buyer's Guide to Passive House Windows

Passive House is the most rigorous energy performance standard in the built environment. A certified Passive House building uses 60–80% less energy than a conventionally built equivalent — and its windows are a critical part of that equation. If you're building or renovating to Passive House standard in the US, this guide explains exactly what your windows need to achieve and how our VEKA and Schüco systems deliver it.

1. What Is Passive House?

The Passive House standard (Passivhaus in German) was developed at the Passivhaus Institut (PHI) in Darmstadt, Germany in the early 1990s. It defines a building's total primary energy demand, heating demand, cooling demand, and airtightness through measured performance, not prescriptive specifications.

The core Passive House requirements:

• Space heating demand: ≤ 15 kWh/m²/year (about 5% of what a typical US home uses for heating)
• Primary energy demand: ≤ 120 kWh/m²/year (covering all energy uses including appliances)
• Airtightness: ≤ 0.6 air changes per hour at 50 Pa pressure (n50 ≤ 0.6 h⁻¹)
• Thermal comfort: Interior surface temperatures must remain above 17°C (62°F) even in extreme winter conditions

Windows are the primary determinant of whether a building achieves that last requirement. A poorly specified window creates a cold wall adjacent to the glass — below the 17°C threshold — and disqualifies the building from certification regardless of how well the rest of the envelope performs.

2. PHI vs. PHIUS: Which Standard Applies in the US?

The US has two Passive House certification bodies: the original PHI (German standard) and PHIUS (Passive House Institute US), which adapted the standard for US climate diversity. Both are recognized; architects and certifiers may work with either.

Our VEKA Therm-82 Passive carries PHI component certification — the most widely recognized designation for Passive House-compatible windows worldwide. PHIUS projects typically accept PHI-certified components. If you're working with a PHIUS certifier, confirm with them — in our experience, PHI-certified windows are accepted on all PHIUS projects we've supplied.

3. What Passive House Requires from Windows

PHI component certification for windows requires a whole-window U-value (Uw) of 0.80 W/m²K or lower. This is the threshold that ensures the interior glass surface stays above 17°C at -10°C exterior temperature — the PHI design reference condition for central Europe and roughly equivalent to a cold US winter.

For US climates colder than this design condition (Colorado mountains, Upstate New York, Minnesota), the required Uw may need to be lower still. PHI provides a calculation tool for specific climate conditions — our technical team can model this for your project location.

Beyond U-value, Passive House windows must also provide:

• Adequate Solar Heat Gain Coefficient (SHGC) to contribute passive solar gain on south-facing glazing
• Airtight installation — the window-to-wall joint must be sealed with rated membranes and tapes to maintain the building's overall airtightness
• Thermal bridge-free installation — the window sill and reveal details must be designed to prevent heat loss at the frame perimeter

4. VEKA Therm-82 Passive — Full Specifications

The Therm-82's 7-chamber frame profile creates six dead-air zones that interrupt thermal conduction across the full 82mm depth. Combined with the 52mm triple-glazing unit and the fully compressed perimeter seal, it achieves the lowest whole-window U-value of any uPVC system in our range — and well below the PHI 0.80 W/m²K threshold.

5. Schüco MB-104 Passive — Full Specifications

The MB-104 Passive achieves PHI certification in an aluminum system — a significant engineering achievement, given aluminum's inherently high thermal conductivity. The 34mm polyamide thermal break interrupts the aluminum's conductive path so effectively that the whole-window U-value reaches 0.78 W/m²K — below the PHI threshold, in aluminum, with the slim sightlines architects require for modern buildings.

6. Installation Considerations for Passive House Projects

Specifying a PHI-certified window is necessary but not sufficient for Passive House performance. The installation itself must maintain the building's airtightness and minimize thermal bridging at the window-wall junction. Key requirements:

• Airtight connection tape: The joint between window frame and rough opening must be sealed with a rated airtight membrane on the interior face and a vapour-open, water-resistant tape on the exterior. We supply compatible tape specifications with every Passive House order.
• Thermal bridge-free installation: The window should be positioned in the insulation plane of the wall, not at the interior face of the cavity. This is a critical detail — a correctly positioned window in a 0.35 W/(mK) installation achieves significantly better effective Uw than the same window installed on the interior wall face.
• Window-to-PHPP model: For a PHIUS or PHI certification project, every window's orientation, U-value, SHGC, and frame factor must be entered into the Passive House Planning Package (PHPP) energy model. We provide all required data in a standard PHPP-compatible format.

7. How to Order for a US Passive House Project

For Passive House projects, we recommend starting the window specification process early — ideally at design development stage, before the PHPP model is finalized. Here's the process:

1. Contact us with your project brief — climate zone, number of windows, building type, PHPP model if available.
2. We provide a window specification — recommended system (Therm-82 or MB-104 Passive), SHGC specification for each orientation, and all PHPP-required data.
3. You confirm the specification with your certifier — we provide PHI component certificates and all supporting documentation.
4. Custom production — all windows are manufactured to exact sizes for your project. Lead time is 8–12 weeks from order confirmation.
5. Delivery to site — freight direct to your US address with full logistics coordination.

We've supplied VEKA Therm-82 Passive and Schüco MB-104 Passive windows for residential and commercial Passive House projects across the US. For architects and builders requiring ongoing project pricing, our trade partner program provides dedicated support and volume pricing.