F-Series · Fiberglass
GR85 Dual Action Window
The workhorse Passive House window, and the one F-Series system tested and rated to PHI (Passive House Institute). A dual-action fiberglass frame at 85 mm depth, carrying triple or vacuum glazing for the lowest whole-window U-values in the range.
Every F-Series fiberglass frame suits a Passive House project. The GR85 Dual Action is the system that has been tested and rated to PHI (Passive House Institute), so specify it when the target is certification or the lowest possible heat loss. The deep fiberglass frame isolates the glazing edge, and the tilt-turn action gives both trickle ventilation and a wide egress opening from a single handle.
Technical specifications
| Frame depth | 85 mm |
| Frame material | Pultruded fiberglass, powder-coated |
| Glazing pocket | Up to 42 mm |
| Opening | Dual action / tilt-turn, inward |
| Whole-window U-value, ZERO 04 | 0.091 Btu/h·ft²·°F (0.52 W/m²K), R-11.0, at NFRC size 1200 × 1500 mm Calculated |
| Whole-window U-value, ZERO 05 | 0.095 Btu/h·ft²·°F (0.54 W/m²K), R-10.5 Calculated |
| Passive House certification | Certified Passive House Component, phA (cold and cool, temperate climates), Passive House Institute, valid through Dec 31, 2026 Certified |
| Installed U-value (Passive House Institute) | Uw,installed 0.65 W/m²K (0.114 Btu/h·ft²·°F) in EIFS, wood-frame and ICF walls Certified |
| Coldest interior surface (Passive House Institute) | 13.2 °C (55.8 °F) at −10 °C (14 °F) outside · temperature factor 0.77 Certified |
| Center-of-glass U-value | ZERO 04: 0.044 to 0.047 Btu/h·ft²·°F (R-21 to R-23) · ZERO 05: 0.054 (R-18.5) Calculated |
| SHGC, center of glass | KØLD 0.49 / 0.35 · MILD 0.35 / 0.27 · HEIT 0.26 / 0.20 (ZERO 05 / ZERO 04) Calculated |
| Visible light, center of glass | KØLD 76% / 64% · MILD 67% / 53% · HEIT 61% / 45% (ZERO 05 / ZERO 04) Calculated |
| Air leakage | 0.03 cfm/ft² at 1.57 psf (0.15 L/s·m² at 75 Pa) Tested |
| Structural rating | CW-PG45 to AAMA/WDMA/CSA 101/I.S.2/A440-17, tested by Intertek, ±45 psf design pressure, no water penetration at 13.53 psf Tested |
Certified values are issued by the Passive House Institute; NFRC and CSA values are published as testing completes. Calculated values come from LBNL THERM and WINDOW models of the specific assembly. Project-specific values depend on size and glass package.
What is a tilt-and-turn (dual action) window?
A tilt-and-turn window, also called a dual-action window, does two jobs from a single handle. Turn the handle one way and the whole sash swings inward like a door for full ventilation, easy cleaning from inside, and a clear egress opening. Turn it the other way and the sash tilts inward at the top only, for secure background ventilation with the opening out of easy reach. All of the operating hardware is concealed inside the frame. It is the standard operable window across Europe, and it is the right choice wherever a window has to both ventilate securely and open wide.
Thermal section (THERM heat map)
GR85 Dual Action Window · Sill. Whole window 0.091 Btu/h·ft²·°F (R-11.0) with ZERO 04, 0.095 (R-10.5) with ZERO 05, at 1200 × 1500 mm. Calculated
Modeled in LBNL THERM 8.1 at NFRC winter conditions, 0°F outside and 70°F inside. The red band on the room side shows the frame and glass staying close to room temperature; the lines are isotherms every 3°C (5.4°F). On the GR85 the head and jambs use the same frame section as the sill.
Full engineering image ›All sections, ZERO 04 (PDF, 5.9 MB) ›ZERO 05 (PDF, 5.9 MB) ›Every section we model ›
Glass & glazing options
Standard glazing is the hybrid vacuum unit in one of six ZERO packages: three climates, each at two levels. ZERO 05 Daylight admits the most light and solar heat; ZERO 04 Ultimate has the lowest U-factor.
| Package | Center-of-glass U / R · SHGC · visible light |
| KØLD 05 · cold | 0.054 / R-18.5 · 0.49 · 76% |
| KØLD 04 · cold | 0.047 / R-21.1 · 0.35 · 64% |
| MILD 05 · mixed | 0.054 / R-18.6 · 0.35 · 67% |
| MILD 04 · mixed | 0.044 / R-22.6 · 0.27 · 53% |
| HEIT 05 · hot | 0.054 / R-18.6 · 0.26 · 61% |
| HEIT 04 · hot | 0.044 / R-23.0 · 0.20 · 45% |
Quanex Super Spacer® Premium silicone-foam warm-edge spacer, argon-filled outer cavity.
Triple glazing, laminated and acoustic build-ups are also available to suit the project. Compare the ZERO packages ›
