When purchasing a new car or replacing broken glass, owners often find an “IRR” or “AS” marking on the surface with a number, without understanding what exactly they received as standard. This is it athermal glazing, which visually looks like ordinary transparent glass, but has completely different physical properties for transmitting heat and light. Unlike standard solutions, coloring of the mass of material is not used here, but a complex technology of introducing microscopic particles of metal oxides directly into the structure is used.
The main task of such a coating is to create a barrier to infrared radiation, which heats the interior, while remaining transparent to the visible spectrum. Production technology allows you to achieve the effect of a “thermos” in winter and air conditioning in summer, significantly reducing the load on the car’s climate system. Many drivers confuse this type of glazing with tinting, but the difference lies in the physics of the process: tinting darkens and absorbs light, while athermal glass reflects thermal energy.
If you notice that the windshield has a slight greenish or bluish tint at a certain angle of incidence of the sun's rays, this is a sure sign of the presence of a special coating. Manufacturers use various chemical compounds, most often based on silver, which gives the characteristic shade. It is important to understand that athermal glass - this is not just a marketing ploy, but a real engineering solution that affects comfort and safety.
Physical principle of operation and material composition
The technology is based on the use of a multilayer coating, which is applied to the inner surface of the outer layer of glass during its manufacturing process. This is a thin film containing ions of silver or other precious metals, which works as a selective filter. It transmits visible light, which is necessary for the driver to see, but reflects long-wave infrared radiation, which carries thermal energy.
The production process requires high precision, since violation of the layer application technology leads to uneven reflection of light and the appearance of optical distortions. Athermal glasses often called “smart” because their properties depend on the angle of incidence of the light: the higher the sun and the straighter the rays, the more efficient the reflection. That is why, in the summer heat, the interior of a car with such glazing heats up much more slowly.
There is a misconception that such glasses completely block ultraviolet radiation. In fact, quality material blocks up to 99% of UV rays, which is critical for preserving upholstery from fading and protecting the driver's skin from the harmful effects of the sun. However, it is worth remembering that over time, the effectiveness of spraying may decrease due to mechanical damage or the use of aggressive chemicals when washing.
- 🔹 High reflectivity of infrared rays, reaching 80% depending on the manufacturer.
- 🔹 Visible spectrum transparency that meets strict road safety standards.
- 🔹 Reducing the temperature in the cabin by 10-15 degrees compared to regular glazing on a hot day.
When washing a car with athermal glass, avoid using abrasive sponges and alkaline chemicals so as not to damage the thin metal coating layer.
Main types of markings and their interpretation
To distinguish real athermal glass from ordinary glass, just carefully examine the markings located in the lower corner of the canvas. Manufacturers are required to apply special codes that indicate the type of material and its characteristics. The most common tag is the word IRR, which is short for English Infrared Rejecting - rejects infrared radiation.
You can also find the designation AS with numbers. For windshields, only the marking is relevant AS1, which means that the light transmission is at least 70%, which meets the legal requirements of most countries. If there is a mark on the glass AS2 or AS3, this means that the material is intended for side or rear windows where transparency requirements are lower.
Some manufacturers, for example, Pilkington or Saint-Gobain, can use their own notation, such as Blue, Green or Ice. These names refer to the color cast that appears when viewed from an angle and indicates the presence of an athermal layer. The absence of markings or the presence of only the car manufacturer's logo without additional codes often indicates that the glass is ordinary, even if it has a slight tint effect.
Labeling secrets
Sometimes manufacturers duplicate markings in the form of microscopic dots or logos around the perimeter of the glass, which are visible only under a magnifying glass or under certain lighting. This helps to identify the originality of the product when purchasing a used car.
| Marking | Meaning | Installation location | Light transmission |
|---|---|---|---|
| IRR | Athermal (heat reflective) | Frontal, side | > 70% (frontal) |
| AS1 | High transparency | Head-on | Minimum 70% |
| AS2 | Medium transparency | Side, rear | Any |
| Tint | Dyed in bulk | Any | Depends on color |
Key differences from tinting and painted glass
The main misconception of car owners is that they equate athermal properties with simple tinting. Tinted windows They work on the principle of light absorption: a dark film or colored mass absorbs solar energy, heats up themselves and transfers heat inside the cabin. Athermal glass, on the other hand, reflects energy while remaining relatively cool to the touch from the outside.
Tinted glass has a uniform dark color throughout the entire thickness of the material. They do reduce the brightness of light, but their effectiveness against thermal radiation is much lower than that of silver-plated technologies. In addition, darkening the windshield often leads to problems with traffic police inspectors, while clear athermal glass is completely legal.
⚠️ Attention: Installing additional film over athermal glass may reduce its effectiveness or lead to the appearance of rainbow effects (“lenses”) that distort the picture. Do not glue metallized films to such glass!
Another important difference is cost. Athermal glasses significantly more expensive to produce and replace than regular or simply tinted counterparts. However, this difference in price is compensated by fuel economy (the air conditioning runs less) and the preservation of the interior. At the same time, it is almost impossible to visually distinguish them from ordinary glass in cloudy weather without special markings.
Advantages of using athermal glass
The first and most obvious advantage is the microclimate in the cabin. Even when parking in the sun in the summer heat, the temperature inside the car does not rise as rapidly as in cars with conventional glazing. This allows you to get into the car with greater comfort and quickly reach the desired air temperature after starting the engine.
The second important aspect is interior protection. Plastic dashboards, leather seats and fabric upholstery are susceptible to damage from exposure to ultraviolet radiation. UV filters, built into athermal glass, extend the life of the materials, preventing them from cracking and fading. This is especially true for cars that are often left in open parking lots.
The third factor is driver safety and comfort. Reducing heat load reduces fatigue, since the body does not have to waste resources on thermoregulation. In addition, the absence of glare and “thermal shudder” of the air above the hot dashboard improves visibility in hot weather.
- 🔹 Fuel savings due to less load on the air conditioning system.
- 🔹 No need to use additional sun screens or curtains.
- 🔹 Maintaining high transparency of glass at night, which is critical for safety.
Disadvantages and possible operational problems
Despite the obvious advantages, the technology also has its disadvantages, which you should know about before buying a car or replacing glass. The main disadvantage is the high price. Replacing a broken windshield with markings IRR can cost 2-3 times more than a regular analogue, which becomes a significant blow to the budget in the absence of CASCO.
The second nuance is related to the operation of parking sensors and radars. The metallic layer, which reflects heat, can partially shield the signals from sensors if they are located behind glass (for example, cameras or cruise control radars). Manufacturers usually make special “windows” sprayed, but when installing non-original glass, interference with the operation of the systems may occur ADAS.
⚠️ Attention: When installing a new windshield, be sure to check for cutouts for rain and light sensors. Incorrect installation may impair the operation of the vehicle's security systems.
There is also the problem of the "lens effect". Cheap analogues of athermal glass may have uneven coating, which under certain lighting creates iridescent stains. This not only irritates the eyes, but also distorts the perception of the colors of traffic lights and road markings, which is unacceptable for the windshield.
☑️ Glass quality check
Impact on electronics and navigation
Modern cars are crammed with antennas, which are often built directly into the glass. The metal layer of the athermal coating should theoretically create a “Faraday cage” that blocks radio signals. However, engineers long ago solved this problem by leaving special areas without spraying in the area of rear-view mirrors or around the perimeter where GPS, GSM and radio antennas are located.
Problems can only arise when using low-quality Chinese analogues, where the transparency zone for signals is made incorrectly or is missing. In this case, the driver may notice a deterioration in the reception of the GPS navigator or a decrease in the signal level of the mobile phone when the smartphone is lying on the dashboard.
For automatic braking and adaptive cruise control systems, whose radars are located behind the manufacturer's logo at the top of the windshield, glass uniformity is critical. Any distortions in the spray structure can lead to false alarms or system shutdowns. Therefore, for such cars it is recommended to use only original glass or certified high-level analogues.
Recommendations for care and washing
Athermal coating is located inside the glass (usually on the inside of the outer layer in triplex), so it is difficult to damage it mechanically. However, the outer surface requires careful handling. When using scrapers to remove ice, you must be careful not to leave scratches that will create glare in the sun.
When washing a car, you should avoid aggressive solvents that may react with the adhesive layer of the frame or damage the hydrophobic coating if it is applied on top. Glass cleaning should be done with soft microfiber cloths and specialized products without ammonia, which is harmful not only for spraying, but also for tinting, if it is on the side windows.
If you notice that the glass has become less able to hold heat or strange color spots have appeared, this may indicate the beginning of the process of degradation of the adhesive layer or oxidation of the metal. In this case, you should consult with a specialist, although most often this is just a visual effect that does not affect functionality.
Athermal glass is an investment in comfort that pays off in reduced fuel consumption and health benefits, but requires careful attention when replacing and washing.
Frequently asked questions (FAQ)
Is it possible to stick tint film on athermal glass?
This is technically possible, but it is not recommended to use metallized films, since the double layer of metal can create interference and a rainbow effect. It is better to choose high-quality polymer films with a high level of light transmission, so as not to disrupt the operation of the sensors and not lose the benefits of the athermal layer.
Is it true that paid parking cannot be passed through athermal glass?
This is a myth. Modern systems for reading license plates and RFID tags operate in ranges that are not blocked by spraying, since in the area of the windshield (where the transponder is located) the spraying is often absent or weakened. Problems can only arise with very cheap or defective glass.
How to check if glass is athermal without markings?
The easiest way is to use the TV's IR remote control. Point the remote control through the glass at the TV receiver. If the signal passes through weakly or not at all, the glass has a high reflectivity of IR rays. You can also look at the glass at an angle: a characteristic greenish or purple tint indicates the presence of spraying.
Is it necessary to register the replacement of ordinary glass with athermal glass with the traffic police?
No, replacing glass with one of similar transparency characteristics (marked AS1) does not require changes to the documents. The main thing is that the light transmission of the windshield is at least 70%, which is the standard for athermal glass.
Why is athermal glass more expensive than regular glass?
The high price is due to the complexity of the production technology: the need for vacuum deposition of rare earth metals, multi-stage quality control and the use of more expensive raw materials. The process requires high-precision equipment, which increases the cost of the final product.