Window film reference

Six terms, six different questions

A percentage on its own is incomplete. Start with what the rating measures, then read how it was measured.

VLT / VT: visible light transmission

The visible light passing through the tested system. Higher means more light. VLT often uses a percentage; VT may use a 0–1 scale. For the same measurement, 0.50 equals 50%. Check whether the value is for film alone or film on stated glass. NFRC rating context.

TSER: total solar energy rejected

The share of total solar energy rejected by the tested filmed glass. Read it with the stated glass and test basis. It is not a prediction of the change in a cooling bill. Definition reference.

SHGC: solar heat gain coefficient

An architectural rating for solar heat gain through the rated system. A lower value means less solar heat gain. Identify the reference window system to understand the result. NFRC rating context.

Glare reduction

A reduction in visible light relative to a reference without the added film. The baseline matters. A rating does not establish comfortable visibility in every setting. Definition reference.

IR: infrared rejection

Read the full metric name, wavelength range, and measurement setup. Narrow-band infrared rejection and broader infrared energy rejection are different measurements in the historical technical-sheet example. Neither label should be substituted for TSER.

VLR: visible light reflectance

The visible light reflected by the tested material or system. Check whether interior and exterior reflectance are listed separately. Appearance also needs to be considered in the relevant lighting. Definition reference.

Four details that give a rating context

1. Product: the exact film, shade or finish, and technical-sheet revision.
2. Glass: the reference material, thickness, coatings, and pane construction.
3. System: film alone, film with liner, film on glass, or a complete reference window.
4. Method: the procedure, units, wavelength range, and relevant baseline.

If a detail is missing, leave the conclusion open. A precise-looking value does not fill a gap in its test basis.

What the numbers cannot establish

A performance sheet alone does not determine glass compatibility, legal compliance, safe visibility, protective performance, warranty coverage, or energy savings for a specific project. Those questions need their own evidence and the relevant professional or official assessment.

For more context and certification questions, read the full specifications guide.