Electrochromic glass by SageGlass

See below how SageGlass by Saint-Gobain can contribute to WELL criteria: Daylighting fenestration

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Key contribution

With SageGlass, exposure to natural light can be optimized, while unwanted heat gain and glare can be controlled with less effect on comfort and energy performance than standard glass.


To optimize occupant exposure to daylight and limit glare through enhanced fenestration parameters.

Detailed requirement

Part 1: Window Sizes for Working and Learning Spaces

The following conditions are met on façades along regularly occupied spaces:

  • Windowwall ratio as measured on external elevations is between 20% and 60%. Percentages greater than 40% require external shading or adjustable opacity glazing to control unwanted heat gain and glare.
  • Between 40% and 60% of window area is at least 2.1 m [7 ft] above the floor (Daylight Glass).

Part 2: Window Transmittance in Working and Learning Areas

The following visible transmittance (VT) conditions are met for all non-decorative glazing:

  • All glazing located higher than 2.1 m [7 ft] from the floor (Daylight Glass) has VT of 60% or more.
  • All glazing located 2.1 m [7 ft] or lower from the floor (Vision Glass) has VT of 50% or more.

Part 3: Uniform Color Transmittance

All windows used for daylighting meet the following requirement:

  • The visible light transmittance of wavelengths between 400 and 650 nm does not vary by more than a factor of 2.

Part 4: Window Sizes for Living Spaces

Window/wall ratio as measured on external elevations is:

  • Between 30% and 60% in living rooms.
  • Between 20% and 40% in bedrooms.


See detailed requirement for Daylighting fenestration

Our contribution

Thanks to SageGlass, a window-to-wall ratio up to 60%—the maximum allowed by WELL—is possible. That’s because the unwanted heat gain and glare can be controlled with less effect on comfort and energy performance than standard glass. 

Depending on the configuration (double pane or triple) and the color, SageGlass in its clearest state has a visible transmittance of 60%, which WELL requires for this feature. However, instead of modulating the opacity, which inherently means the view would be obscured when it is opaque, SageGlass modulates the tint, therefore occupants always have a view to the outdoors.
Did you know? 
Daylight and views are essential to our well-being, development and health. Research studies have suggested a 18% increase in productivity, and a 10% to 25% improvement in cognitive performances in offices with more natural light and views to the outdoors (Source: WORLD GREEN BUILDING COUNCIL: HEALTH, WELLBEING & PRODUCTIVITY IN OFFICES, THE NEXT CHAPTER FOR GREEN BUILDING).

Boston Museum of Science with SageGlass