February 2014

Volume 23, Number 2

Download EBN digital editions

Smartphone/tablet edition

Kindle edition

Get the PDF

perfect for printing

Article Contents

Passive House Windows and Doors Continue to Wow

Printer-friendly versionSend to friend

Exciting new doors and windows featuring cork, composites, and low U-factors have come to U.S. markets.

By Candace Pearson


The Makrowin MW88G2 line is foam-free and uses cork to insulate the frame.

Photo: European Architectural Supply

For evidence of the growing influence of the Passive House standard, look no further than the North American market for efficient windows and doors, where new and innovative products engineered to meet the standard seem to appear all the time. Case in point: an entire “Passive House Zone” at the 2013 Greenbuild conference was dedicated to featuring Passive House manufacturers and service providers.

Among the new wave of highly efficient windows and doors, some are going beyond the strict energy criteria set by the Passivhaus Institute (PHI) to offer additional green features and innovations designed to reduce overall environmental impact. Most frontrunner products are imported, suggesting European manufactures continue to lead in quality (see “European Windows for Passive House Buildings”). However, U.S. manufacturers have begun to certify windows through the international standard and may soon offer products with competitive performance and lower embodied transportation energy.

European Architectural Supply

European Architectural Supply (EAS) offers two lines of Passivhaus-certified windows and doors. The Schüco ThermoPlus line with PVC frames (also called the Schüco Alu Inside) is offered in several configurations based on the amount of insulation used, but only the most insulated is PHI-certified. Advertised as “uPVC,” or unplasticized PVC, this material is equivalent to the PVC used in most vinyl windows. The system has seven chambers that can be left “naked,” according to to Patrik Muzila from EAS, or filled with polystyrene insulation inserts—a material that carries health concerns because of the chemical HBCD (see “Polystyrene Insulation: Does It Belong in a Green Building?”). However, the inserts significantly increase the energy efficiency of the frame, lowering the U-factor from U-0.16 (R-6.3) to U-0.14 (R-7.1), and if an additional multiple-chamber insert is also added, the frame achieves U-0.13 (R-7.7) and is PHI certified, according to Muzila. The system achieves a whole-window U-value of 0.11 (R-8.7). This system is EAS’s less-expensive Passive House option, starting at $36 per square foot.

EAS also offers the Makrowin MW88G2 line, which is foam-free and uses cork to insulate the frame. As a biobased, sustainably managed, and rapidly renewable material, expanded cork avoids the hazardous chemicals of foam and offers structural stability that could increase the windows’ durability. The wood windows and doors of the Makrowin MW88G2 line incorporate sustainably harvested cork from Portugal and can be built using wood certified by the Forest Stewardship Council (FSC). “The cork maintains rigidity so that we are not compromising the structural integrity of the window,” according to Muzila.

Its insulating properties also allow for a slimmer profile. The company claims Makrowin windows are the thinnest PHI-certified wood windows, achieving a whole-window U-value of 0.12 (R-8.6) at 3.46 inches thick (88mm). Extruded aluminum cladding is offered for the exterior, and triple glazing from Saint-Gobain provides a solar heat-gain coefficient (SHGC) up to 0.62. The company works with Passive House designers to adjust SHGC values for different sides of the building. Makrowin windows start at $52 per square foot.

Klearwall Windows and Doors

Klearwall offers EcoClad, a line of aluminum-clad wood windows and doors that are manufactured in Ireland. These windows have an aluminum exterior, a PVC-encased polyurethane insulating core, and a wood frame interior. These composite windows, offering the interior aesthetics of wood with the exterior durability of aluminum, can achieve a whole-unit U-factor down to 0.13 (R-7.7).

Ewen Utting used EcoClad for the Equilibrium House, a San Francisco home certified to the Passive House Institute U.S. (PHIUS) building standard. “A wood window needs maintenance and doesn’t stand up in ten years,” Utting told EBN.The aluminum will last, the vinyl performs, and the wood cladding creates the feel of wood.”


Three-latch multipoint locking improves both airtightness and security, according to Groke, which is currently seeking Passivhaus certification for its doors.

Image: Groke

Utting also found the price was less than that of German equivalents. According to Klearwall sales director Brendan Harte, these windows are a comparatively affordable option starting at $35–$40 per square foot. Utting was convinced to “go with a company no one has ever heard of” because of added perks: FSC-certified wood for the interior pane comes standard, and the Klearwall factory harnesses energy from two onsite wind turbines and a co-generation plant.

Groke Aluminum Entry Doors

Groke entry doors are currently pursuing PHI certification, but they are worth keeping in mind because, unlike many companies that only offer Passive House doors when you buy a large number of windows, Groke sells high-performance entry doors individually.

Groke doors are available in three thicknesses based on how much extruded polystyrene insulation they contain—0.94" (24mm), 2.52" (64mm), or 3.70" (94mm)—with triple glazing that comes standard on the upper two thicknesses. Doors with 64mm of insulation have an overlay panel on the outer skin of the door, and the 90mm doors have overlay panels on both sides. These all-aluminum doors achieve a whole-unit U-factor that ranges from U-0.257 (R-3.9) down to U-0.13 (R-7.7), and they are powder coated.

According to Allen Nelson, product manager at Groke, people are usually interested in Groke doors either for energy efficiency or security, but in reality, the features overlap. Three-latch multipoint locking is more secure and better seals the door against the gaskets, which prevents air leakage, he claims. Most Groke doors are rated class 4 in the air permeability test DIN 12207—exceeding the requirement for PHI certification.

Groke doors are expensive, typically ranging from $3,000 to $8,000; costs for the custom-made shipping crate alone can amount to $500. However, “there is a real lack of doors that meet Passive House criteria,” Nelson told EBN. “We are finding that, in a lot of cases, our customers are willing to pay for a high-end residential entry door.”

More in GreenSpec

These products are welcome additions to the roughly half-dozen Passivhaus-certified or near-certified windows already listed in our GreenSpec directory; see all the options here.

Comments (0)

Post new comment

Welcome !
  • Web page addresses and e-mail addresses turn into links automatically.
  • Lines and paragraphs break automatically.
  • Glossary terms will be automatically marked with links to their descriptions. If there are certain phrases or sections of text that should be excluded from glossary marking and linking, use the special markup, [no-glossary] ... [/no-glossary]. Additionally, these HTML elements will not be scanned: a, abbr, acronym, code, pre.

More information about formatting options

February 3, 2014