Thermochromic Glass


Verre thermochromique

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Prel-Shade Insulating Glass Unit:

  • Prel-Shade is a thermochromic glass system that changes color when heated by the sun 
  • Minimized solar heat gain, lightens and darkens by itself, with absolutely no mechanical intervention, according to changing levels of ambient temperature and sunlight
  • Adaptive system that transitions seamlessly between light and dark, improve natural daylight quality
  • Offers the same benefits as a regular laminated glass : impact resistance, increased security, reduced sound penetration, blocks the transmission of damaging UV light almost completely


  • The Prel-Shade system consists of a double insulated unit, usually 31 mm thick, composed of one 13 mm lite of laminated glass on the exterior, an air space of 11.5 mm and an interior glass lite of 6 mm.
  • During periods of strong sunshine, the glass warms up and becomes darker, reducing solar gain in the interior of a building.  When the strength of the sun diminishes, at the end of the day for instance or on cloudy days, the glass stays clearer, providing a greater degree of natural light.

    Component options

    • Glass : clear, tinted (grey, bronze, green, blue, etc), low-e
    • Interlayer : thermochromics
    • Filling gas : argon or air
    • Sealants : black silicone, black polyisobutylene

    Standards and Certification

    • CPSC 16 CFR 1201 – Safety Standard for Architectural Glazing Materials.
    • Prel-Shade has successfully passed the Accelerated Aging tests ASTM G555-05a and ASTM E2141-06.


      • Vertical Glazing : punch windows, curtain wall, solariums, greenhouses, swimming pools and interior spas
      • Sloped Glazing : skylights, canopies, roof windows

      Production Capacity

      Manufacturing Specifications
        mm po
      Minimum Dimensions 150  x 300 6 x 12
      Standard Maximum Dimensions1 1650 x 3660 65 x 144
      Total thickness Double insulated units2 31 1 7/32
      Triple insulated units3 47 1 7/8

      1 : The maximum glass weight cannot exceed 318 kg (700 lb.).  Certain conditions may apply.  Contact us for further information.
      2 : Exterior laminated glass 13 mm / air space 11.5 mm / interior glass 6mm.
      3 : Exterior laminated glass 13 mm / air space 11.5 mm / middle glass lite 6mm / air space 11.5 mm / interior glass 6mm.


      Clic on thumbnail to enlarge image.


      Chrysler DealershipIan S. Malcolm Architects / Thermochromic Glass / Barrie, ON

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      Gatineau ProjectThermochromic Glass

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      Documentation to download

      Green Buildings
      Thermaspec : Performance Calculating Tool
      Technical Assistance