Answers to the most frequently asked questions.
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• Appearance (when viewed from the exterior): the aesthetic appearance of the glass (colour, intensity, reflection) depends on 4 factors:

- Orientation of the building
- Surrounding environment
- Glare
- Amount of direct sunlight

The final choice must be made after viewing samples of the proposed glass types in their intended location.

The overall performance of a window is dependent on the combined effect of frame and glazing components and the air-tightness of the finished window. Ratings maybe improved by decreasing thermal losses.


Decreasing thermal losses

-Type of Low-E glass: with its optimised balance of very low emissivity and high solar gain SGG PLANITHERM can improve the energy index for a given window

-Inert Gas filling: argon gas filling can improve the energy index for a given window compared to an air filled unit

-Optimised cavity width: the optimum cavity width for an argon filled unit is 15mm (10mm with krypto)

-Warm edge spacer: Using SGG SWISSPACER can improve the energy index for a given window compared to standard aluminium spacer bars

-Triple glazing: can further reduce glazing U values

-Frame type: U values can be reduced with advanced materials and design

There have three major considerations when we need choose high advanced energy saving glazing: The light Transmittance (TL), the U- value, and Shading Coefficient (SC). 

The light transmittance is the ratio of the transmitted light flux to the incident light flux. Usually, the higher TL, the more natural day light.

Heat transmittance through a surface by conduction, convection and radiation is expressed by its U-value.  Usually, the lower the U- value, the lower the heat loss. 

The solar factor of glazing is the percentage of the total solar radiant heat energy entering the room.  Usually, the lower the SC, the less solar radiant heat energy entering the room through the glass.


You may need to choose the glass product according to the local building regulations. Normally in the north region of China, it is cold and severe cold area, then the lower U- Value becomes the most important factor for you when choose the glass. For example, the SGG PLANITHERM is most popular in north regions, with higher Light transmittance, and lowest U-Value=1.16 w/m2.k (with 6+16Ar+6). 

Or in severe cold area, the triple double glazing unit with low-e coating is also one of the best solution for enery saving.

In certain circumstances, the colours of some materials, when exposed to direct sunlight, can fade.  Materials can change colour when exposed to solar radiation. The most efficient way of preventing fading is to exclude ultra-violet radiation, since despite its low proportion within the electromagnetic spectrum, it is the main contributory factor to the process.

UV radiation can be virtually eliminated by the use of PVB laminated glass.  A second option is to use a body-tinted glass, which will filter light selectivety. Thirdly, glass with a low solar factor could be used to reduce the thermal effect of the radiation.

Solar radiant energy entering a room through the glass is absorbed by interior objects and surfaces, which then retransmit the energy as thermal radiation, mainly in the far infra-red band.  The solar energy entering through the glass is trapped in the room, which then tends to heat up and is referred to as the "greenhouse effect".

Condensation forms very differently depending on whether it is inside or outside the building, due to the thermal bridge effect around the cavity. Surface condention on the internal face always starts in the corners, mainly due to the additional cooling caused by the thermal bridge. The high performance low-E glass, such as SGG PLANITHERM series, or " warm-edge" spacerbars, made of insulating material, such as SGG SWISSPACER, can effectly reduce the risk of condensation at the corners.

After installation it is recommended that the SGG BIOCLEAN is thoroughly cleaned in accordance with our guidelines (document B1 and B2), which can be found on Once installed the coating requires around 10 days to be activated by UV light. Provided the suckers used were in good condition and free of silicon residues, the marks should disappear.

Self-cleaning glass does work, but it is not a 100% maintenance-free product. It requires UV light and rain (or water) to work, so areas where there is the most exposure will show the best results. During dry spells, a rinse with a hosepipe will assist with this rinsing action. For real-life case studies and to see it in action visit our specialist website to view our 'Success Stories' video.

You can download a list of approved products for use with SGG BIOCLEAN self-cleaning glass from the dedicated mini-site in the "Technical Information" section.


This list is also available in the professional area of in the "Technical Support" section under "Glazing".


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