Infrared rejection
Read infrared figures without confusing a narrow measurement with whole-window solar performance.
What the percentage describes
Infrared rejection concerns the part of infrared radiation that a stated test does not transmit through its sample. The label needs a wavelength range, test method and sample construction to be meaningful. Different manufacturers may use different definitions for similar abbreviations.
A figure from one sensor wavelength cannot automatically be compared with an integrated result across a wider infrared range. Even the same percentage can describe materially different tests.
IRR, IRER and total solar energy
Some technical sheets distinguish an infrared rejection figure from infrared energy rejection, or IRER. In a defined IRER calculation, energy absorbed by the glass and film and subsequently flowing inward is taken into account. Read the definition on that particular sheet rather than assuming every label follows it.
TSER covers total solar energy under its specified calculation, including more than infrared alone. It is useful for comparing whole-system solar control when the tested glass and methods are comparable. It still does not directly predict the temperature of every parked car.
Why a demonstration is not a complete comparison
A heat lamp and meter can demonstrate a response under one setup. Lamp spectrum, distance, sensor response, sample temperature and glass can all differ from the conditions represented by a technical performance table. A strong demonstration therefore needs the test conditions stated.
Ask whether the number refers to film alone, film with a liner, or film installed on a particular glass. Do not combine values from unlike test assemblies into a ranking as if the samples were identical.
Choose with visibility and use in mind
Read IR performance alongside VLT, TSER, reflectance and the product installation limits. A light film can provide useful solar control, while the darkest option is not automatically the best fit for every glass position or driver.
Solar control cannot replace safe visibility or local compliance. Obtain the current technical sheet for the exact shade and confirm the installed glass combination. Treat comfort claims as conditional, not a guaranteed cabin-temperature reduction.