Definition of properties
Light reflection (inside / outside)
Percentage of the total visible sunlight (380 - 780 nm) that is reflected (reflected back) inwards or outwards by the film. The higher this value, the more visible sunlight is reflected.
Light transmission
Percentage of the total visible sunlight (380 - 780 nm) that is transmitted from the outside to the inside by the film. The lower this value, the less light penetrates the glass.
The values given are measured values that do not reflect human perception. The reason for this is the enormous brightness of sunlight. For example, if 80% of the daylight (100,000 lx) is blocked by the film, 20,000 lx (the remaining 20%) will still penetrate the film. So it is still very bright in the room. For comparison, you can see different brightness scenarios below:
| Examples of typical illuminance levels | |
|---|---|
| Bright sunny day | 100,000 lx |
| Overcast summer day | 20,000 lx |
| In the shade in summer | 10,000 lx |
| Overcast winter day | 3,500 lx |
| TV studio lighting | 1,000 lx |
| Office/room lighting | 500 lx |
| Corridor lighting | 100 lx |
| Living room | 50 lx |
Solar reflection
Percentage of solar energy (280 - 2500 nm) that is reflected (reflected back) to the outside by the foil. The higher this value, the more radiation is reflected.
Solar absorption
Percentage of solar energy (280 - 2500 nm) that is absorbed (soaked up) by the film and converted into heat. This value is the sum of the secondary heat radiation to the inside and outside. The lower this value, the less energy is absorbed.
Solar transmission
Percentage of solar energy (280 - 2500 nm) that is transmitted from the outside to the inside by the film. The lower this value, the less radiation penetrates the glass.
Shading coefficient
The ratio of solar heat gain through a given glazing system (with window film) to the solar heat gain that would result under the same external conditions if the window were made of clear, double-thickness window glass (without window film). This value thus expresses the solar shading ability of a particular glazing system (with window film) in relation to clear glass without window film as a ratio. The smaller the value, the higher the solar shading ability of the window (with film).
Heat transmission coefficient (U-value)
Factor of the film's conductivity. It indicates the amount of heat flow through the film in relation to time and thus also expresses the insulating capacity.
The U-value is given in BTU (British Thermal Units) per square foot per hour per degree Fahrenheit. The lower this value, the higher the insulating capacity (thermal insulation) of the film.
Total energy transmittance (g-value)
The g-value is the percentage of total radiation passing through the glass. In other words, solar energy that is let through to the inside by radiation transmission and secondary heat radiation. The g-value is calculated as 100% minus the total radiation reduced at the glass (total energy rejection).
Emissivity
This value describes the ability of a given surface to absorb (soak up) or reflect (radiate back) thermal radiation. The lower this value, the less room heat is absorbed, i.e. more heat is reflected back into the room.
UV- reduction
Percentage of total ultraviolet radiation (280 - 380 nm) that is rejected by the film. The higher this value, the less UV radiation penetrates the film.
Infrared (IR) reduction
Percentage of total infrared (IR) radiation (760 - 2500 nm) that is rejected by the film. The higher this value, the less infrared radiation penetrates the film. The short-wave IR-A radiation lies in the wavelength range from 780 to 1400 nm. IR-B radiation is in the wavelength range from 1400 to 3000 nm.
Glarereduction
Glare comes in three different forms (physiological glare, psychological glare, annoyance glare). The latter, nuisance glare, affects the foils and refers to the glare phenomenon that is produced on the foil by car headlights, for example.
The higher this value, the less glare is produced by the film.
Heat reflection (inside)
Percentage of heat radiation (thermal radiation) that is reflected (reflected back) inwards by the film. The higher this value, the greater the insulating capacity (thermal insulation) of the film.
Total energy rejection (outdoor)
Percentage of solar energy that is reflected back by reflection and rejection. The higher this value, the more radiation is reduced.