IRR vs IRER vs TSER: Why the Same Sun Film Shows Different Numbers

IRR, IRER and TSER all describe how much heat a sun film blocks — but they measure different slices of sunlight, and the same film can post a 97% on one and a 54% on another. Neither number is wrong. Here's what each one actually measures, and which one to trust when you're comparing films.

Three Numbers, Three Different Slices of Sunlight

Sunlight carries energy across visible light, ultraviolet, and infrared wavelengths. A film can be tested against a narrow band of that range, a broader chunk of it, or the whole spectrum at once. Narrower measurements read higher, because they only count the part of the spectrum the film blocks best. Broader measurements read lower, because they average in the parts the film blocks less effectively. Same film, same physics — different scope, different number.

IRR (or SIRR): The Narrowest Measurement

IRR — sometimes printed as SIRR, Selective Infrared Rejection — is measured on the film alone, usually at or near a specific infrared wavelength. It's the number most brands lead with because it genuinely reads highest of the three, not because it's inflated. PMD scores every sun film in our catalog on this figure specifically because it's the one nearly every brand actually publishes — using it consistently is what makes a 3M film and a Garware film comparable on the same product page.

IRER: A Broader, More Complete Infrared Number

A smaller number of brands — LLumar is the one we've found so far — also publish IRER, IR Energy Rejection. It covers a wider infrared band and, per the brand's own methodology notes, accounts for heat the glass itself absorbs and re-radiates back into the cabin, not just what passes straight through. That extra scope is exactly why it reads lower than IRR/SIRR on the same film: it's measuring more of the real thermal picture, not less of the film's performance.

TSER: The Only Number That Tells You Total Heat Rejection

Total Solar Energy Rejected steps back further still — it measures the film's effect across the entire solar spectrum reaching your cabin, UV and visible light included, not infrared alone. It's the number that actually corresponds to how much cooler your car feels, which is why PMD leads with TSER for buying decisions and treats IRR as a supporting spec, never the headline one.

A Real Example: One Film, Three Numbers

LLumar's Stratos 50 (56% VLT) posts 97% on the narrow IRR/SIRR measurement, 67% on the broader IRER measurement, and 54% TSER across the full solar spectrum. All three are correct measurements of the same real film. None of them alone tells you what it actually does to your cabin temperature — that's what TSER is for.

How to Compare Films Without Getting Misled

• Always compare TSER first — it's the number closest to "how much cooler does my car actually feel."
• Treat a very high infrared number on its own with a little skepticism — check whether it's labeled IRR/SIRR (narrow) or IRER (broader) before assuming it means the film blocks more heat overall.
• A brand disclosing IRER alongside IRR isn't claiming a better film — it's disclosing more of the same film's real performance.

How PMD Handles It

Every sun film on PMD is scored on the same IRR figure so brands compare fairly against each other. When a brand also publishes the broader IRER number on their own spec sheet, we show it on the product page and mark it with a Transparency+ badge — a disclosure signal, not a score boost. The PMD Index itself never changes because of it. See our full PMD Index methodology for how every sun film is rated.