Window & door systems
Fiberglass windows and doors with hybrid vacuum glass, plus hurricane-rated aluminum for the coast.
Engineered to order for multifamily, commercial, modular and Passive House projects.
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Built for commercial, modular and Passive House & PHIUS projects.
GlasFëns Window Systems USA is a supplier of high-performance windows, doors and façade systems for buildings across North America. Our focus is fiberglass, with aluminum for hurricane and high-wind applications, all based on proven European systems and fitted with German hardware. We exist to do one thing exceptionally well: deliver energy-efficient fenestration that performs at the highest level, approaching zero.
Our components come from manufacturers who have been producing window and door systems for generations, recognized leaders across Europe, with hardware from Roto, Siegenia and G-U, all engineered and made in Germany. That precision and attention to detail is what makes a GlasFëns system perform quietly and reliably for decades.
Glass walls
R‑23 at the center of the glass puts a window wall in the same range as an insulated stud wall, so floor-to-ceiling glass no longer has to be the weak spot in the envelope.
See the glass ›Products
Fiberglass windows and doors from the GR60 to the GR145, plus hurricane-rated aluminum.
F-Series
The lowest heat loss in the range. GR65, GR70 and GR85.
F-Series
Tilt for ventilation, turn for cleaning and egress, from one handle.
F-Series
Outswing casements, with an integrated insect screen on the GR85.
F-Series
Entrance and balcony doors in the GR60, GR70 and GR85 frames.
F-Series
Sliding windows and doors up to the GR145 glass wall.
A-Series
Impact-rated aluminum windows, doors and storefront for the coast.
Performance
Every frame section is modeled in LBNL THERM, and every number on our site says whether it was tested, calculated or depends on your project.
GR85 dual action, sill section · ZERO 04 hybrid vacuum glass
THERM 8.1, NFRC 100 · room 70 °F, outside 0 °F
Glass
Every ZERO package is the same hybrid build-up: an outer lite and an 18 mm argon cavity, stacked with a two-lite vacuum glass unit. It fits the standard F-Series glazing pocket and carries a 25-year warranty on the vacuum unit.
A-Series · Hurricane aluminum
Solid aluminum, impact-rated for hurricane and high-wind zones. Large-missile tested, on a Florida and coastal code basis, in the same clean architectural language as the fiberglass line.
Colors & finishes
For specifiers
U-value and SHGC, condensation, air barrier interface, installation, warranty and more.
THERM sectionsEvery GR70 and GR85 section, modeled at NFRC conditions. Download the full set as a PDF.
Project supportSend the window schedule and we model whole-window values at your sizes, with pricing.
We return whole-window performance at your sizes and a priced package, typically well below the leading American window brands and high-end European imports. Passive House-level performance, without the premium price.