What is Solar Window Film?

person installing window film

Solar window films are a cheap and effective alternative to reduce your room's temperature without taxing your electricity bills. A solar film can guard against 80% of solar heat. Window films also provide privacy. Choosing a darker, more reflective tint can also obscure the outsiders’ view of things inside the house. At the same time, it does not change your view of the outside world. Also, it protects your glass if it should shatter.

What are Solar Films Made of?

Solar films are dyed or metalized polyester laminates. Usually, they consist of several thin sheets of film bound together by an adhesive to form the sheets of various thicknesses. They are available in varying thicknesses, ranging from two mils to 14 mils (1 mil = 25 microns). One side is coated with either a pressure-sensitive or water-activated adhesive film, while the other side is coated with a hard scratch-resistant coat.

Some films that provide UV protection contain chemicals like cyclic-imino-esters, while others contain thin metallic coating made up of either aluminum, stainless steel, silver, or a combination that reflects and absorbs solar radiation.

What to Look For While Choosing a Film

Solar energy is composed of three components: ultraviolet radiation (UV), visible light, and near-infrared light. Visible light and near-infrared light form more than half of the light spectrum. An ideal film should allow most of the visible light to pass and reflect almost all of the near-infrared and UV radiation. An important rating or measure to look for when selecting a film, according to the National Fenestration Rating Council is as follows:

VT or Visible transmittance: VT is the measure of visible light that comes through a product, expressed in numbers between zero and one. A higher VT ensures abundant daylight.

SHGC or Solar Heat Gain Coefficient: It is a measure of the heat energy blocked by the film. This too is expressed in numbers between zero and one. A lower SHSG ensures that more heat gain is blocked by the film. This is an important measure especially for places that have extreme summers.

Tips for Before and After Application

Some films require professional application. The films that can be applied by a novice installer require that the window exterior is cleaned only with a non-ammonia-based cleaner.

In case you have a low E (low emission) glass, find the location of the low E in your window system before applying the film. Once the film is applied it should not be cleaned until the film is cured, some films take as long as 30 days to cure. Check with the vendor for the curing period. In order to clean the film, use a solution of water with a small quantity of soap. Avoid products that are high in ammonia and industrial-strength cleaners or any abrasive solutions or tools that scratch the film.

Shelf Life

IWFA has documented cases of films lasting from 12 to 22 years, but this again varies from product to product. Most quality window films usually provide a five-year warranty. Replace the film when there is visible damage.