Window Film Performance Definition

Window Film Performance Definition

Definitions for Solar Engineering Parameters:

TOTAL SOLAR TRANSMITTANCE :
The ratio of the amount of total solar energy in the full solar wavelength range (300-2,500 nanometers) that is allowd to pass through a glazing system to the amount total solar energy falling on that glazing system. Value is expressed as a percentage.

TOTAL SOLAR REFLECTANCE:
The ratio of the amount of total solar energy which is reflected outward by a glazing system to the amount of total solar energy falling on the glazing system. Value is expressed as a percentage.

TOTAL SOLAR ABSORPTANCE:
The ratio of the amount of total solar energy absorbed by a glazing system to the amount of total solar energy falling on the glazing system. Solar absorptance is that portion of total solar energy that is neither transmitted nor reflected, expressed as a percentage.

VISIBLE LIGHT TRANSMITTANCE:
The ratio of the amount of total visible solar energy (380-780 nanometers) that is allowed to pass through a glazing system to the amount of total visible energy falling on the glazing system. Value is expressed as a percentage. Glare is influenced by visible light transmittance through a glazing system.

VISIBLE LIGHT REFLECTANCE:

The ratio of the amount of total visible solar energy (380-780 nanometers) that is reflected by a glazing system. Value is expressed as a percentage.

SHADING COEFFICIENT:
The ratio of the amount nof the total solar heat gain through a given glazing system to the solar heat gain under the same conditions for clear, unshaded, double-strength window glass (DSA). Shading coefficient defines the sun control capability of the glazing system.

ULTRAVIOLET REJECTION:
The ratio of the amount of total ultraviolet solar energy (300-380 nanometers) that is not allowed to pass throuh a glazing system to the amount of total ultraviolet soalr energy falling on the glazing system. Ultraviolet is one portion of the total energy spectrum which greatly contributes to fading and deterioration of fabric and furnishings.

TOTAL SOLAR ENERGY REJECTED:
The percentage of incidental solar energy rejected by a glazing system. The higher this value, the less solar heat energy is transmitted by the glazing system.

TENSILE STRENGTH:

The force per unit cross-sectional area required to break (under tension) a film. Units given are pounds per square inch.

BREAK STRENGTH:
The force per unit width required to break  (under tension) a film. Units given are pounds per inch.

PUNCTURE STRENGTH:
The force (in pounds) required to puncture a film with a specified test probe.