Glossary of Terms

  • Total Solar Energy: All the energy in the solar spectrum that reaches us on the earth's surface. This includes UVA and B, Visible light, and infrared energy 

  • Transmitted: The amount of total solar energy that passes through the glass, into the building

  • Reflected: The amount of total solar energy that is reflected off of the glass and directed back outside. This energy does not come into the building

  • Absorbed: The amount of total solar energy that is absorbed in the glass. This heats up the glass, making it hotter to the touch, and reradiates a small amount of heat back into the room. The majority of absorbed energy is kept out of the room
  • Visible Light: The portion of the solar spectrum containing visible light that we can see – it contains all the colours of the spectrum

  • Transmitted: The amount of visible light that passes through the glass, into the building. This is how light or dark the film is, eg:  35%

  • Reflected Interior: The amount of visible light that is reflected off the interior surface of the window. This is seen when standing inside the building looking out.  A higher reflectance value means the window looks more like a mirror from the inside
  • U Factor (Winter): Heat transfer due to the temperature differences outside and inside.  Represents the amount of heat passing through 1sq ft of glass in 1 hour for every 1 degree temperature difference between the outside and the inside. A lower value means less heat passes through - this is generally of interest for keeping heat inside the building in cold climates
  • Emissivity: The ability of the surface to reflect infrared energy.  For window film, this means how much heat it will reradiate back into the room.  Low E glass and films have low emissivities, which means they reflect a lot of heat back into a room, which is the desired effect in cold climates
  • Ultraviolet Light Rejected: The amount of UV energy blocked by the film, either by reflecting or absorbing it.  This energy does not enter the building
  • Glare Reduction: The reduction in visible light transmitted compared to clear unfilmed glass
  • Luminous Efficacy: The ratio of visible light transmission to solar heat transmission for a window.  A higher luminous efficacy means the film has a high heat rejection given its VLT
  • Shading Coefficient: The ratio of heat passing through a filmed window to heat passing through clear unfilmed glass.  A lower number means better heat rejection
  • Solar Heat Gain Coefficient: Similar to the shading coefficient, except the value also takes into account energy that is reradiated back into the room from the glass heating up due to increased absorption.  Again, a lower number means better heat rejection

  • Infared Rejection:  The amount of infrared (IR) energy that is blocked by the film, either by reflecting or absorbing.  This value is for the whole IR region of the solar spectrum