TERMINOLOGY TO GUIDE YOU

Solar control window films are designed to specifically control the sun’s electromagnetic energy. Because of this, you can select a window film product based on the transmittance, reflectance and absorptance performance characteristics. Performance results are provided for three distinct regions within the spectral distribution of solar radiation and they are: ultraviolet, visible and near-infrared.

With this information one can decide whether a particular film meets or exceeds expectations for aesthetics, occupant comfort and total solar energy rejection performance.

Transmittance

Measures the percentage of solar energy and visible light (daylight) that passes through a glazing system. All solar control films reduce visible light transmission in order to provide solar heat control. Lighter films tend to transmit higher levels of solar energy and visible light while darker and more reflective films have lower transmittance levels.

Absorptance

Measures the percentage of solar energy and visible light that are absorbed by the window film. As absorptance levels of a particular film increase, so will the temperature of the glass. Always refer to a manufacturer’s film-to-glass installation recommendations.

Reflectance

Measures the percentage of solar energy and visible light that are being reflected by the window film. Highly reflective films offer high heat rejection capability.

Newer technology films need not be dark nor highly reflective to provide impressive solar energy performance.

Emissivity

Measures the surface’s ability to absorb or reflect far-infrared radiation. The lower the emissivity the higher the far-infrared reflection.

U-Value

A measurement of heat transfer due to outdoor/indoor temperature differences; describing the dealt loss through a material. The lower the U-Value, the less heat transfers.

Shading Coefficient (SC)

The ratio of solar heat gain passing through a glazing system to the solar heat gain that occurs under the same conditions if the window were made of clear, un-shaded double strength window glass. The lower the number, the better the solar shading qualities of the glazing system.

Total Solar Energy Rejected

Measures the window film’s ability to reject solar heat in the form of visible light and invisible infrared radiation.

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