Window Film Infrared Rejection vs. TSER: Read the Heat Claim Correctly

Architectural window-film education · September 28, 2026

Start with the measurement window

Solar radiation includes ultraviolet, visible and solar-infrared energy. The European Window Film Association's technical paper uses 300–2500 nanometers for its whole-solar discussion and 780–2500 nanometers for solar infrared. A nanometer, abbreviated nm, is a unit of wavelength. These boundaries define the scope of the comparison; they are not percentages of energy. EWFA technical paper, pages 2–4.

An infrared-only figure leaves out the visible and ultraviolet portions of incoming solar energy. That omission matters even when the full solar-infrared interval is measured accurately. The error occurs when an IR percentage is retold as the percentage of all solar heat kept out. It is equally misleading to assume every infrared figure measures only a tiny slice: the manufacturer example below explicitly covers 780–2500 nm.

There are two separate differences: scope and accounting

IR rejection / IRR: read the definition, not just the abbreviation

“IR rejection” alone does not establish a common test across every advertisement. Ask for the wavelength range, whether the sample was film alone or film on glass, and what the manufacturer includes in the calculation. EWFA distinguishes selective infrared rejection from IRER and explains why handheld measurements can differ from laboratory data. A narrowly measured result can be useful within its stated limits; it cannot stand in for a whole-solar result. EWFA, page 4.

IRER: account for solar infrared that ends up indoors

IRER addresses the 780–2500 nm solar-infrared range while accounting for energy absorbed by the glazing and subsequently released inward. This is the important second distinction: energy that did not pass directly through the sample has not necessarily been kept outside permanently. Some absorbed energy can contribute to interior heat gain. EWFA describes IRER as similar to TSER but limited to solar infrared, and contrasts it with selective rejection that considers only directly transmitted energy. EWFA, pages 3–4.

TSER: widen the accounting to the whole solar range

TSER describes total solar energy rejected by the glazing, not just the infrared part. Its companion gain measure, solar heat gain coefficient (SHGC), includes direct solar transmission and the inward portion of absorbed solar energy. Under a matching calculation basis, TSER is the complement of solar heat gain, expressed as a percentage. Do not mix a center-of-glass value with an unrelated whole-window rating or combine numbers from different reference assemblies. EWFA, page 3.

In short, changing the wavelength range changes what energy is counted; changing the treatment of absorbed energy changes where that energy is counted as going. Both must match before percentages are compared. This is a solar-metric discussion, not an insulating-performance test. For the separate distinction between solar control and long-wave thermal exchange, see low-e versus solar-control window film.

Read a real manufacturer row without changing its meaning

Madico's publicly available Architectural Film Performance Measurements sheet, retrieved September 28, 2026, lists the following values for its Nova 70 row. The file is dated March 15, 2023 in its filename; retrieval in 2026 does not make it a newly issued specification. It states that values are read in accordance with NFRC standards and calculated on single-pane 6 mm (1/4-inch) clear glass. Manufacturer sheet and footnotes.

Annotation one: this is not a narrow-band example. The footnote covers the full stated solar-IR interval, yet IR rejection and IRER still differ. Blaming every discrepancy on a tiny measurement window misses the accounting issue. The sheet identifies the range but does not print a complete derivation of each IR column; EWFA supplies the conceptual distinction, not a reconstruction of unpublished manufacturer calculations.

Annotation two: keep the numbers attached to their labels. The row does not claim 78% total solar rejection. Its TSER field says 46%. The infrared and whole-solar figures cannot be added together: their energy scopes overlap rather than representing separate savings buckets. The same restriction applies to adding UV rejection to infrared rejection.

Annotation three: this is a reading example, not a procurement specification. The manufacturer says these are typical properties and should not be used as a specification. The listed reference glass may differ from your glazing. This citation establishes neither NFRC certification for an individual product nor current availability, suitability, dealership or endorsement by Sarasota Window Tinting. Confirm current product documentation before a real project.

Why a heat-lamp or pocket-meter demonstration is not enough

A demonstration may show a difference under its particular lamp, sample and sensor conditions. It does not automatically establish the full-solar performance of an installed window. EWFA explains that portable infrared instruments generally measure limited ranges or individual wavelengths, while laboratory spectrophotometers measure transmission and reflection across the solar spectrum. It also notes that film-only measurements differ from film applied to glass. EWFA, page 4.

Ask what the display actually measures before accepting a spoken “heat blocked” claim. If the demonstration has no wavelength range or documented relationship to the proposed assembly, treat it as an illustration rather than a rating. There is no need to dismiss all demonstrations as dishonest; simply do not use a selective instrument reading to override a properly identified manufacturer performance table.

Turn the distinction into a better window-tinting decision

Suppose your Sarasota workspace is uncomfortable when direct afternoon sun reaches it. Start with that specific observation, not a demand for the highest IR number. For otherwise suitable options, compare whole-solar gain or rejection on a consistent glass and calculation basis, then separately consider visible transmission, reflected appearance and the room's use. A larger infrared percentage alone cannot settle those trade-offs or predict a temperature change.

TSER is also not a percentage reduction in an electricity bill, nor is it automatically the percentage improvement over your untreated window. The untreated glass already has its own solar performance. Translating assembly data into an improvement requires the starting condition; translating it into energy use requires building and operating information. Do not let a window metric silently become a whole-property savings promise.

1. Clarify the claim: “Is that IR rejection, IRER or TSER, and what range and calculation does it use?”
2. Clarify the comparison: “Are both options reported on the same glass, with the same method and application conditions?”
3. Clarify the outcome: “What supports the proposed solar-gain improvement, and what remains uncertain about daylight, appearance and my windows?”

Once the terminology is clear, use our window-film rating-verification guide to trace the proposed product and supporting rating records. That page owns the evidence trail; this page explains why different metric labels must not be exchanged. Physical eligibility is another separate decision: review film and glass compatibility before assuming a performance value makes a product suitable for coated, insulated or other specific glazing.