Three heat numbers, and which one to trust
LLumar's performance data sheet gives three ways of measuring heat, and they produce very different numbers for the same film:
- TSER, total solar energy rejected, counts everything the sun sends through the glass. It's the fairest single comparison.
- IRER, IR energy rejection over 780–2500 nm, counts infrared that's absorbed and re-radiated as well as reflected. The sheet calls it the more complete infrared measurement.
- SIRR, selective IR rejection, measures solar infrared not transmitted directly. It's the biggest number, 85–88% on IRX, and the one most marketing quotes.
A quote that says "blocks 88% of heat" is quoting SIRR as if it were TSER. On the same IRX 15 film, TSER is 59%. Both are true, but they measure different things.
What the comparison shows about dyed and ceramic film
Dark dyed film rejects heat mostly by absorbing light, so its TSER rises as it gets darker: ATC 05 rejects 44%, ATC 50 only 28%. Ceramic film rejects infrared you can't see, so even its lightest shades keep a high IRER: IRX 50 matches IRX 05 at 60%. That's the case for ceramic on a car where you want heat control without a dark look. The ceramic versus dyed comparison covers price and appearance too.
Clear film and the windshield
AIR 80 and AIR 90 are near-clear, at 77% and 84% VLT, yet AIR 80 keeps an IRER of 60%, the same as the IRX shades. That's why clear ceramic is the usual choice on glass where you don't want darkness. In BC, the windshield below the top 75 mm and the front side windows can't legally carry film of any kind, clear included. The law checker covers each window.
UV is the same across the board
Every film on the sheet blocks more than 99% of UV between 300 and 380 nm, from the cheapest dyed shade to the clearest ceramic. The Skin Cancer Foundation notes that side and rear glass "does not block UVA rays effectively", so any of these films closes that gap. If UV is your main reason, darkness doesn't buy you anything extra; the UV answer has the detail.
From numbers to a quote
The shop's starting prices are for ATC: rear glass from $240 on a sedan or pickup, $260 on a full-size SUV. IRX and AIR are upgrades quoted per package, because the price depends on how many windows and how complex the glass is. The IRX film page lists the shades the shop stocks.