Sorpetaler Windows

Credit: Custom Trades International

What makes this product green?

  • Reduces heating and cooling loads
  • Durable or low-maintenance


The German window manufacturer Sorpetaler makes high-performance windows, including those that meet strict PassivhausA residential building construction standard requiring very low levels of air leakage, very high levels of insulation, and windows with a very low U-factor. Developed in the early 1990s by Bo Adamson and Wolfgang Feist, the standard is now promoted by the Passivhaus Institut in Darmstadt, Germany. To meet the standard, a home must have an infiltration rate no greater than 0.60 AC/H @ 50 pascals, a maximum annual heating energy use of 15 kWh per square meter (4,755 Btu per square foot), a maximum annual cooling energy use of 15 kWh per square meter (1.39 kWh per square foot), and maximum source energy use for all purposes of 120 kWh per square meter (11.1 kWh per square foot). The standard recommends, but does not require, a maximum design heating load of 10 W per square meter and windows with a maximum U-factor of 0.14. The Passivhaus standard was developed for buildings in central and northern Europe; efforts are underway to clarify the best techniques to achieve the standard for buildings in hot climates. standards. Frames are triple-laminated wood or metal clad wood and are available with argonInert (chemically stable) gas, which, because of its low thermal conductivity, is often used as gas fill between the panes of energy-efficient windows. -filled, low-e coatings, triple-pane glazingWhen referring to windows or doors, the transparent or translucent layer that transmits light. High-performance glazing may include multiple layers of glass or plastic, low-e coatings, and low-conductivity gas fill.. FSCNonprofit organization that promotes forestry practices that are sustainable from environmental and social standpoints; FSC certification on a wood product is an indicator that the wood came from a well-managed forest.-certified wood options are available as are additional glazing options. To protect the wood, the windows are finished using a penetrating primer and two coats of acrylic sealant. The company's Visiostar window is available with integral exterior metal blinds. Although the company has not completed NFRC testing, the company lists U-factors as low as 0.20 based on European testing.

Additional Info

Product Attributes

  • Minimum NFRC U-factor: 0.2


  • Forest Stewardship Council (FSC)

Manufacturer Information

Sorpetaler USA
129 Stonehedge Dr., N
Greenwich, CT 06831
Phone: 203-561-5915
Fax: 203-561-5915

Listed in: Wood Windows