What TSER Means and Why It Is Not the Whole Story

TSER stands for total solar energy rejected. It describes how much of the sun's total incoming energy is rejected by the glass and film system.

That total includes more than infrared. Solar energy is commonly discussed in three main parts:

• Ultraviolet
• Visible light
• Infrared

That matters because TSER is often oversimplified in window film sales. A film with 85% TSER should not automatically be described as "85% heat rejection."

A better explanation is:

The film rejects 85% of total solar energy under the tested condition.

That is useful information, but it still needs context.

TSER in Plain English

TSER tells you how much total solar energy is rejected before it passes through the glass and film system.

A higher TSER usually means stronger solar control performance. If one film has a TSER of 45% and another has a TSER of 70%, the 70% film is rejecting more total solar energy in the tested condition.

But "total solar energy" is not the same as "only heat."

The sun's energy includes UV, visible light, and infrared. Each part affects the job conversation differently.

Part of solar energy	What it affects in a window film conversation
UV	Fading, UV protection, material damage
Visible light	Brightness, glare, daylight, view, appearance
Infrared	Radiant heat and heat-comfort conversations

This is why TSER can be helpful, but it should not be used as a shortcut.

How UV, Visible Light, and IR Contribute to TSER

Spec sheets often list UV rejection, visible light transmission, IR rejection, and TSER near each other.

Those numbers are related, but they are not equal-sized pieces of the solar energy total.

A simplified way to think about the sun's energy at the glass is:

Solar energy bucket	Approximate share of total solar energy	What it usually affects
UV	About 3-8%	Fading and UV protection
Visible light	About 42-43%	Brightness, glare, daylight, and appearance
Infrared	About 49-55%	Radiant heat and comfort

The exact split changes depending on the source, wavelength range, atmosphere, and test method. The practical point stays the same: UV, visible light, and IR do not contribute equally to TSER.

That is why a high number in one category should not be treated like total solar energy rejection.

A Simple TSER Example

Here is a simplified example.

A spec sheet might list:

Spec sheet item	Example value
UV Rejection	99%
Visible Light Transmission / VLT	40%
IR Rejection	80%
Approx. TSER	73%

Actual spec sheets usually list VLT, not "visible light rejected."

So if a film has 40% VLT, that means about 40% of visible light is transmitted. For a simplified teaching example, you could think of that as roughly 60% of visible light being rejected or not transmitted through the system.

Using a simple solar-energy split:

Solar energy bucket	Approximate share	Example rejection	Approximate contribution
UV	5%	99%	About 5 points
Visible light	43%	About 60%	About 26 points
Infrared	52%	80%	About 42 points
Simplified total	100%	—	About 73%

This is not a manufacturer rating, and it is not a replacement for tested TSER data.

It is just a practical way to see why the pieces do not carry the same weight.

A 99% UV rejection number sounds huge, but UV is a small portion of the total solar energy.

A high IR rejection number usually matters more to comfort because IR is a larger portion of the solar energy total, but IR rejection still does not equal TSER by itself.

Visible light matters too. A darker film can raise solar energy rejection by reducing more visible light, but that may also make the room darker than the customer wants.

Does TSER Include IR Rejection?

Yes, generally speaking, TSER includes the infrared portion because infrared is part of total solar energy.

But TSER is not the same as IR rejection.

IR rejection usually refers to how much infrared energy is rejected within the range being measured. TSER is broader. It includes the solar energy contribution from UV, visible light, and infrared.

That is why two films can tell different stories:

• One film may show a high IR rejection number but a lower TSER.
• Another film may have strong TSER partly because it reduces more visible light.
• A darker film may improve TSER while changing the room's appearance more than the customer wants.

For installers, this is where the sales conversation needs to stay clean. High IR rejection, high TSER, and strong comfort performance are related, but they are not the same claim.

Why 85% TSER Is Not the Same as 85% Heat Rejection

This is where the language can get loose.

If a film has 85% TSER, that means it rejects 85% of total solar energy in the tested glass condition.

It does not mean the customer will feel exactly 85% less heat in the room.

There are a few reasons for that.

TSER includes UV, visible light, and infrared. It is not an infrared-only number.

Visible light can still affect heat once it enters the room and is absorbed by floors, furniture, walls, and other surfaces. But when a customer hears "heat rejection," they are usually thinking about comfort, not a solar-spectrum calculation.

Room comfort also depends on the building. Glass area, window direction, sun angle, partial shade, HVAC, room size, insulation, interior surfaces, and air movement all affect what the customer feels after installation.

The glass system matters too. A film tested on one glass type may not behave the same way on every window in the field.

So the cleaner statement is:

"This film rejects 85% of total solar energy under the tested condition."

Not:

"This film blocks 85% of the heat."

That small wording change keeps the claim more accurate.

Why TSER Matters on Flat Glass Jobs

TSER is still a useful number.

It helps installers and estimators compare solar control films when the customer's main issue is heat from direct sun.

It can help with conversations like:

• "This room gets hot in the afternoon."
• "The lobby heats up through these windows."
• "We want better solar control without guessing from darkness alone."
• "Which film rejects more total solar energy?"

TSER is especially useful when it helps separate appearance from performance. A film does not have to be judged only by how dark it looks.

But TSER should be paired with the other numbers on the spec sheet.

What TSER Does Not Tell You

TSER does not tell you the whole job story by itself.

It does not tell you:

• How dark the film will look
• How much visible light passes through
• How much glare will be reduced
• How reflective the film will look from inside or outside
• How much solar energy is absorbed by the glass
• Whether the film is compatible with the glass
• Whether the film is suitable for a Low-E coating
• Whether partial shading could create added concern
• Whether the customer will like the appearance after installation

This is why TSER should be used as part of the performance conversation, not as the only selling point.

TSER and Glass Risk

TSER itself is not usually the risk number.

The bigger concern is how the film and glass system handle the solar energy. A film can reject solar energy by reflecting it, absorbing it, or reducing transmission through the glass.

Absorbed solar energy can raise glass temperature. That can matter on certain glass types, Low-E coatings, insulated glass units, shaded glass, or partially exposed windows.

Before recommending a film based mainly on TSER, consider:

• Glass type
• Single pane vs insulated glass
• Low-E coatings
• Solar absorption
• Interior vs exterior installation
• Window size
• Existing glass damage
• Edge condition
• Partial shading
• Sun exposure and orientation
• Manufacturer film-to-glass charts or guidance

A high TSER number can be attractive, but it does not automatically mean the film is right for every window.

TSER vs VLT

TSER and VLT answer different questions.

VLT tells you how much visible light passes through the glass and film.

TSER tells you how much total solar energy is rejected.

A customer may assume a darker film always rejects more heat, but that is not always the best way to compare products. Some films are designed to control solar energy while keeping a more neutral or lighter appearance.

A good customer explanation is:

"VLT tells us how light or dark the film may feel. TSER tells us how much total solar energy is rejected. We need both numbers to understand the balance between appearance and solar control."

TSER vs SHGC

SHGC stands for solar heat gain coefficient. It describes how much solar heat gain passes through the window system.

For building performance conversations, SHGC is often the more direct solar heat gain number. TSER tells you what is rejected. SHGC helps describe what still enters as solar heat gain.

That does not make TSER useless. It just means TSER should not be treated as the whole comfort story.

How to Explain TSER to a Customer

A simple way to explain TSER is:

"TSER tells us how much total solar energy the film and glass system rejects. That includes UV, visible light, and infrared. It is useful for comparing solar control, but it is not the same as saying the room will feel that exact percentage cooler."

That explanation is more accurate and avoids overselling the number.

Installer Takeaway

TSER is useful, but it is often oversold.

Use it when comparing total solar energy rejection. Use it when a customer is concerned about solar heat. Use it to show that darkness and performance are not always the same thing.

But do not turn TSER into a simple "heat blocked" claim.

For flat glass jobs, TSER should be read alongside VLT, IR rejection, SHGC, reflectance, absorption, glass type, coating information, shading conditions, and manufacturer guidance.

The better question is not just:

"Which film has the highest TSER?"

The better question is:

"Which film gives the right solar control for this glass, this exposure, and this customer's goal?"

Related Terms

• VLT
• SHGC
• IR Rejection
• Heat Rejection
• UV Rejection
• Solar Absorption
• Solar Reflectance
• Solar Transmittance
• Film-to-Glass Compatibility