Low-e coatings and double glazing


Energy consumption has been a source of growing concern over the past few decades, and limiting heat losses through glazing is a priority for glassmakers. AGC Glass Europe and its R&D Centre have long worked to improve the insulating properties of glass by applying coatings on it.


AGC Glass Europe boasts a wide range of super-insulating coated glass, also called low-emissivity (low-e) glass and unified under the iplus and Planibel brand names.


Comparison of single glazing versus double glazing and double low-e glazing


Single glazing has a U value of 5.8 W/(m²K). In such a case more heat is lost through the window compared with solar gain: the overall balance is a clear loss of energy. This loss of energy must be compensated by extra heating corresponding to emission of 84 kg of CO2 per year per square metre of glass, or 2,000 kg of CO2 per dwelling per year.
The use of ordinary double glazing with a U value of 2.8 W/(m²K) improves the balance by reducing the amount of heating needed, but it still remains negative with an overall energy loss corresponding to 22 kg of CO2 per square metre of glass, or 500 kg per dwelling per year.


Now if we compare on the one hand the energy used and the CO2 emitted to produce the glass, and on the other the energy and the CO2 saved by using low-e double glazing, the balance is positive. To produce 1 square metre of Thermobel Energy, with a U value of 1.0, the industry emits around 35 kg of CO2. By contrast, replacing single glazing by low-e double glazing leads to a saving of about 91 kg per year. 

Double glazing AGC glass

CO2 balance comparison between single glazing (lower bar), basic double glazing (middle bar), and low-e double glazing (upper bar).


That means that the CO2 emitted to produce the low-e double glazing is offset by the savings in 3.5 months. If conventional double glazing is replaced by Thermobel EnergyN low-e double glazing, the time needed to cancel out the CO2 emission is 10.5 months. 


AGC Glass Europe supports the communication efforts by Glass for Europe, the trade association for European manufacturers of building, automotive, and transport glass, on the importance of providing products that can generate energy savings, reduce CO2 emissions and create healthier buildings. According to this trade association, today in Europe, over 85% of glazed areas in buildings are still inefficient because of either single glazing or outdated double glazing. A EU window energy label should guide consumers towards more energy efficient windows, using an A to G scale to identify the performance of products. 

For more information see the “Window Energy Label” initiative (http://windowenergylabel.eu/) or watch the info video. For detailed information read http://www.glassforeurope.com/images/cont/166_43490_file.pdf.


With its complete and diverse iplus and Planibel ranges of low-emissivity products, AGC Glass Europe continues to design solutions that meet all comfort requirements. In addition, AGC Glass Europe also offers a wide range of insulating glazing units marketed under the brand name Thermobel using insulating coatings (such as Thermobel Advanced 0.8), Stopray Ultra using a triple silver coating and Fineo, combining insulating coatings with vacuum technology.


Thermobel Advanced 0.8 –Double glazing

Thermobel Advanced 0.8

Thermobel Advanced 0.8 is a double glazing providing an extremely high level of thermal insulation. It combines the exceptional insulation performance of a standard triple insulating glazing (U value of 0.8 W/m².K) with the installation benefits of double glazing (compact thickness, lightweight). This is achieved by having a specific composition of low-e coatings combined with a thermal gas-filled spacer. Light transmission is maximised (LT= 72%) and the solar factor permits maximum use of free solar heat (SF = 50%). Thermobel Advanced 0.8 is the best insulating double glazing currently available on the market. It is the ideal product for anyone looking for a compact, light and high-performance glass solution.

Connector- Brussels Airport - Architect Chapman Taylor

Stopray Ultra – Triple silver-coated products

AGC Glass Europe offers triple silver-coated products for facade applications in commercial buildings. Stopray Ultra-50 on ClearvisionStopray Ultra-60 and Stopray Ultra-70 on Clearvision are part of AGC Glass Europe's high-performance glazing solutions. The high level of light transmission maximises natural light, yielding all the benefits of large indoor spaces bathed in light year-round. The very low solar factor reduces solar gain, resulting in significantly lower air conditioning costs. The selectivity (ratio of light transmission to solar factor) is always higher than 2. The superb thermal insulation (thanks to the U value of 1.0 W/m².K) minimises energy losses, resulting in major energy savings.


Fineo vacuum insulating glazing

AGC has developed a new generation of double glazing with very high insulation performance thanks to vacuum technology. 

The new product, named Fineo, combines thermal and acoustic insulation properties as good as or even better than triple glazing. It consists of a double glazing made of two sheets of glass, each with a minimum thickness of 3 mm, one having a super-insulating coating, separated by a 0.1 mm vacuum gap. Thus the total thickness (less than 1 cm) is a fifth to a quarter that of conventional double glazing units and their weight is one third lighter.

The Fineo vacuum double glazing offers a thermal insulation ratio Ug of 0.7 W/(m²K) with the future possibility to achieve 0.4 W/(m²K) compared with 1.1 for super-insulating double glazing and 2.8 for ordinary double glazing.

Finally the thinness of the vacuum glass affords better light transmission.



Triple glazing

At a time when reducing energy consumption is taking centre stage and buildings are designed for minimal fossil fuel demand over the life span – both for financial and for environmental reasons – triple glazing is increasingly being used for new constructions, major renovation, passive houses, nearly zero energy buildings and projects in the residential, utility and commercial sectors.


AGC's triple glazing Thermobel TG range has excellent light and energy properties and as a result minimises heat loss – approximately four times less than normal double glazing – and makes maximum use of the free solar heat.

Thermobel TG LS is a triple glazing unit specially developed by AGC Glass Europe. The objective is a transparent building product with high environmental performance while letting in as much natural light as possible for best visual comfort and wellbeing (low U value combined with high solar factor).


This is possible thanks to the unique properties of iplus low-e coatings and its glass substrate that can be Planibel Clearlite or Planibel Clearvision. The wide range of low-e coatings (iplus LS, iplus Top 1.1, iplus Top 1.1T, iplus Advanced 1.0 and iplus Advanced 1.0T) will help architects choose the best glazing for every building. Thermobel TG LS is especially suitable for passive houses or nearly zero energy houses.

Thermobel TG LS products offer a higher level of light transmission thanks to the Planibel Clearlite glass component. Thanks to the unique properties of the iplus low-e coatings and Planibel Clearlite, Thermobel TG LS meets the criteria for PH and nZEB houses and buildings and is recommend in renovation projects for private home owners and building projects.

Triple glazing AGC
thermobeltri triple glazing AGC

IRIS coating for automotive glass


CO2 emissions are directly correlated with car fuel consumption, and there are basically two ways to reduce this by using glass. The first is to decrease the weight of the glass. The thinner the glass the lower the energy consumption of the car. The second way is to improve the thermal properties of the glazing. Given that air conditioning can increase fuel consumption by 10%, improving the thermal insulation will reduce the fuel consumption.

The sun’s spectrum is made up of three kinds of radiation: ultraviolet, visible and infrared. In an ordinary windshield, the ultraviolet is absorbed by the polyvinyl butyral (PVB) interlayer, but the visible and infrared radiation is mainly transmitted through the glass.


The visible and infrared ranges are responsible for 54% and 43% respectively of the energy transferred into the car. One of the major functions of the windshield is of course to provide high visibility for the driver, and therefore regulations impose a minimum visible light transmission of 70%. The problem is as follows: how to significantly reduce the energy transmission through the windshield while maintaining sufficient transmission of visible light? The IRIS® coating developed by AGC provides an answer to this question.


The IRIS coating is a complex stack of different thin metallic coatings, deposited directly onto clear glass by the magnetron sputtering process. After coating, the glass can be curved and laminated in conventional windshield production lines.


The IRIS windshield provides high visible light transmission (more than 70%) and high infrared reflection. These unique properties permit energy reflection of about 35% compared with 5% for a conventional windshield. 


The total energy entering the car is decreased by 10% compared with the best absorption technologies in which part of the energy absorbed inside the windshield is re-emitted into the car. This technology decreases the thermal load inside the vehicle and consequently the need to use air conditioning for cooling the interior.

AutomoviteIRIS glazing AGC

Based on simulations by AGC and our customers, the IRIS windshield is estimated to decrease CO2 emissions by 1 g/km.
Comfort is also improved for the driver and passengers. Our simulations show that the temperature of the dashboard and seats can be lowered by 9°C, making them less hot to the touch. This further reduces the use of air conditioning.

Given the total amount of CO2 emissions in Europe generated by transport (according to EIA, www.eia.doe.gov), reducing the CO2 emissions for each vehicle by 1.5 g/km would cut annual CO2 emissions in Europe by 6 million tonnes.
Beyond this impressive statement, AGC considers that this kind of product has a bright future, especially for the new electric vehicles for which the challenge will no longer be CO2 emissions but the power savings necessary to achieve sufficient driving range.


Thin Automotive Windshield


In a bid to reduce the carbon footprint of vehicles, AGC Glass Europe is the first company to have overcome industrial and technical challenges to offer a thin windshield with a thickness of just 3.9 mm (as opposed to the usual 4.5 mm for a standard windshield). In practical terms, this means that the thin windshield is some 1.4 kg/m² lighter than its standard counterparts.


This translates into a saving of approximately 0.2 g of CO2 per km travelled whilst accommodating manufacturers' requirements in terms of safety (strength and optical quality), aesthetics (shape and colour) and adaptability to the customer’s process.