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

Look at enough sun-film spec sheets and you'll notice something odd: one brand quotes 97% infrared rejection, another quotes 67% for what looks like a similar film, and a third leads with a TSER number in the 50s. None of them are lying — they're measuring different things and calling the results by similar-sounding names.

Three Numbers, Three Different Slices of Sunlight

Sunlight carries energy across a wide range of wavelengths — visible light, ultraviolet, and infrared. A film can be tested against just one narrow band of that range, a broader chunk of it, or the whole thing at once. Narrower measurements tend to read higher, because they're only counting 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's genuinely the highest-reading of the three, not because it's inflated or false. PMD scores every sun film on this figure specifically because it's the one nearly every brand in our catalog 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 band of infrared wavelengths and, per the brand's own methodology notes, accounts for heat energy 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.

What This Means When You're Comparing Films

• Always compare TSER first for real-world heat rejection — 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. PMD marks that with a Transparency+ badge, not a higher score.