It’s important to know that when a number is used to describe TSER, the higher the number, the greater the amount of total solar energy (heat) is rejected. Many window films will reject anywhere from 30% – 80% TSER. A general rule of thumb is that window films with a high TSER percentage are typically darker and allow less visible light to enter the room. If visible light is important then you must also determine how much you are willing to sacrifice to reach your desired TSER. On the other hand, IR rejection measures the majority amount of heat that can be rejected from infrared.