To understand why IR rejection alone can be misleading, it helps to first understand how solar energy works.
Sunlight is made up of three major energy bands:

• Ultraviolet (UV): approximately 3%–6%
• Visible Light: approximately 44%
• Infrared Radiation (IR): approximately 50%–53%

Together, these form the total solar spectrum.

Infrared radiation is indeed the largest contributor to heat gain through glass. However, visible light also carries a substantial amount of solar energy. A film that allows large amounts of visible light and solar transmission can still contribute significant heat into a building even if it advertises extremely high IR rejection figures. This is why evaluating only IR rejection gives an incomplete picture of real heat performance.

Here is where the marketing game begins. When some manufacturers advertise:
• 95% IR rejection
• 97% IR rejection
• 99% IR rejection
the figure is often measured only across a narrow infrared wavelength band — commonly around 900nm to 1000nm. The issue is that actual solar infrared energy spans a much wider range: 780nm to 2500nm

A film can achieve extremely high rejection at a narrow wavelength peak while performing significantly less impressively across the broader infrared spectrum encountered in real sunlight. In other words: A film may reject 99% IR at one specific wavelength while allowing considerably more infrared energy through across the full solar range.
That distinction matters.

Many consumers assume “99% IR rejection” means:
• 99% total heat rejection
• 99% cooler interiors
• near-total solar blocking

But technically, that is not what the number means. Without stating:
• the wavelength range tested
• the testing methodology
• the full solar performance data
the IR figure alone can become more of a marketing statistic than a reliable performance indicator.

TSER stands for Total Solar Energy Rejected

Unlike isolated IR measurements, TSER evaluates the total amount of solar energy prevented from entering the glass system, including:
• ultraviolet energy
• visible light energy
• infrared energy

It measures the overall solar heat reduction performance of the glazing system.
The higher the TSER:
• the lower the solar heat entering the room
• the lower the cooling load
• the greater the thermal comfort near windows

This is why two films with similar “99% IR rejection” claims can perform completely differently in actual installations.

Consider this example:

Film A
• Advertised IR rejection: 99%
• TSER: 42%
• High absorption-based ceramic construction

Film B
• Advertised IR rejection: 85%
• TSER: 68%
• Reflective sputtered construction

Despite the lower IR marketing figure, Film B may reduce significantly more total solar heat in real-world conditions.
Why? because total heat rejection is not determined by narrow-band IR performance alone.

A quality sputtered or dual-reflective film can reject energy across a broader portion of the solar spectrum rather than concentrating only on selective infrared peaks.

This distinction becomes especially important in Singapore’s climate.

Singapore experiences:
• strong year-round solar exposure
• prolonged west-facing afternoon heat
• consistently high cooling loads

Different film technologies manage solar energy differently.

Absorptive Films:
Many ceramic or dyed films absorb solar energy into the film and glass system before dissipating it.

Reflective / Sputtered Films:
Sputtered and dual-reflective films reject a larger portion of solar energy outward at the glass surface before it enters the building envelope.

This is one reason why films with lower advertised IR figures can sometimes outperform films with higher IR claims when evaluated by TSER and SHGC.

Another important point many consumers overlook:

A higher TSER does not automatically mean a better film.

A film can achieve very high TSER simply by being:

• extremely dark
• highly reflective
• heavily tinted

This is why professionals compare TSER together with:

VLT — Visible Light Transmission

VLT measures how much natural light passes through the film.

The correct way to evaluate window film performance is:

• compare films within similar VLT ranges
• then evaluate which film delivers better TSER

For example:

Film B is significantly more efficient because it rejects more solar energy while maintaining similar brightness levels.

For many Singapore homes and offices, the ideal balance is often:

• VLT between 40%–60%
• lower SHGC values
• higher TSER without excessive darkening

This helps maintain:

• daylight
• outside visibility
• occupant comfort
• reduced glare
• lower air-conditioning demand

Another specification worth understanding is:
SHGC — Solar Heat Gain Coefficient
SHGC measures how much solar heat passes through the glazing system.

Lower SHGC means:
• less solar heat enters the room
• better thermal performance

TSER and SHGC are directly related:
TSER=(1-SHGC)\times100
Higher TSER corresponds to lower SHGC.

For west-facing Singapore windows exposed to intense afternoon sun, lower SHGC values can substantially improve indoor comfort and reduce cooling loads.

Reliable solar performance data should be backed by recognised industry standards such as:
• NFRC 200
• ASTM E903
• ISO 9050

These standards help ensure:
• consistent testing methodology
• fair comparison between products
• verified solar performance measurements

If a specification sheet heavily promotes IR rejection but omits:
• TSER
• SHGC
• VLT
• certified testing standards

you should request complete performance data before making a decision.
Any reputable installer using certified architectural film brands should be able to provide full performance specifications.