F-Series · Fiberglass
GR85 Fixed Window
The lowest heat loss in the range. A fixed 85 mm fiberglass frame with hybrid vacuum glass reaches a whole-window U-value of 0.081 (R-12.4), for picture windows, transoms and the fixed lites of a larger elevation.
With no sash to carry, the frame face narrows to about 64 mm and nearly all of the opening is glass, which is where a vacuum unit insulates best. Specify GR85 fixed units wherever a window does not need to open, and pair them with the GR85 Dual Action or Casement where a room needs fresh air or an egress opening. The same 85 mm frame and finish carry across all three, so the elevation reads as one system.
Technical specifications
| Frame depth | 85 mm |
| Frame material | Pultruded fiberglass, powder-coated |
| Frame face width | About 64 mm (2½ in) |
| Glazing pocket | Up to 42 mm |
| Opening | Fixed, non-operable |
| Whole-window U-value, ZERO 04 | 0.081 Btu/h·ft²·°F (0.46 W/m²K), R-12.4, at NFRC size 1200 × 1500 mm Calculated |
| Whole-window U-value, ZERO 06 | 0.090 Btu/h·ft²·°F (0.51 W/m²K), R-11.1 Calculated |
| Reversed frame | ZERO 04: 0.080 (0.45 W/m²K), R-12.5 · ZERO 06: 0.089 (0.51 W/m²K), R-11.2 Calculated |
| Center-of-glass U-value | ZERO 04: 0.038 to 0.042 Btu/h·ft²·°F (R-24 to R-26) · ZERO 06: 0.054 (R-18.5) Calculated |
| SHGC, center of glass | KØLD 0.49 / 0.37 · MILD 0.35 / 0.28 · HEIT 0.26 / 0.19 (ZERO 06 / ZERO 04) Calculated |
| Visible light, center of glass | KØLD 76% / 65% · MILD 67% / 56% · HEIT 61% / 41% (ZERO 06 / ZERO 04) Calculated |
| Air leakage | 0.01 cfm/ft² at 1.57 psf (0.05 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 published as NFRC and CSA 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 fixed window?
A fixed window is glazed into a frame that does not open. With no sash, hinges or locks, it has the slimmest frame for its size, the most glass, the lowest air leakage and nothing to wear out or adjust. Fixed windows are used for picture windows, transoms and sidelights, glass that is high or hard to reach, and the non-opening lites of a larger window wall.
Codes still call for opening windows for ventilation and emergency escape in many rooms, so fixed units are usually combined with dual-action or casement windows in the same elevation.
Thermal section (THERM heat map)
GR85 Fixed Window · Sill. ZERO 04 hybrid vacuum glass. Whole window 0.081 Btu/h·ft²·°F (R-12.4) with ZERO 04, 0.090 (R-11.1) with ZERO 06, 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 18 sections (PDF, 2.9 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 06 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 06 · cold | 0.054 / R-18.5 · 0.49 · 76% |
| KØLD 04 · cold | 0.042 / R-24.1 · 0.37 · 65% |
| MILD 06 · mixed | 0.054 / R-18.6 · 0.35 · 67% |
| MILD 04 · mixed | 0.039 / R-25.7 · 0.28 · 56% |
| HEIT 06 · hot | 0.054 / R-18.6 · 0.26 · 61% |
| HEIT 04 · hot | 0.038 / R-26.2 · 0.19 · 41% |
Super Spacer® Premium 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 ›
