Glossary
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.
The portion of the solar spectrum containing visible light that we can see – it contains all the colours of the spectrum.
The amount of visible light that passes through the glass, into the building. This is how light or dark the film is, e.g.: 35%.
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.
The reduction in visible light transmitted compared to clear unfilmed glass.
The amount of infrared (IR) energy that is blocked by the film, either by reflecting or absorbing. This value is for the whole IR.
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.
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.
The ratio of heat passing through a filmed window to heat passing through clear unfilmed glass. A lower number means better heat rejection.
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.
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.
The amount of total solar energy that passes through the glass, into the building.
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.
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.
The amount of UV energy blocked by the film, either by reflecting or absorbing it. This energy does not enter the building.
