window glass
High-quality window glass
Glass is one of the main elements of a window. But what types of glass are there and what functions do they have? In principle, any glass window can be combined with any profile material. The different types of glass are produced using special manufacturing processes or coatings. They sometimes differ from one another in terms of thickness, weight and their respective functions and benefits. What requirements should your window glass meet – energy saving, sound insulation, security or privacy? Of course, several functions can also be combined in one glass, it’s entirely up to you.
Which is better, double glazing or triple glazing?
This depends on the weather conditions and window installation conditions in your location. If the exterior wall insulation is poor, you should buy double glazing windows or upgrade the insulation of the exterior wall to triple glazing. Triple glazing is recommended for new buildings with good insulation. The price is slightly higher than double glazing, generally around 10%. But in the long run, the investment is definitely worth it due to lower heating costs.
Glass types and their functions at a glance
The surface of glass is either coated with a thin film or treated chemically or physically. This creates many different types of window glass with special functions, structures or colors.
| Glass type | Function |
| Insulating glass, heat-insulating glass | Improve insulation, reduce energy costs |
| Soundproof glass | Reduce annoying noise |
| Safety glass (VSG/ESG) | Provide anti-theft protection, personal protection |
| Decorative glass, mirror glass, tinted glass, satin or sandblasted glass, frosted glass | Provide privacy protection, decorative element |
| Sun-proof glass | Reduce heat and glare |
| Self-cleaning glass | Reduce cleaning work |
Light transmittance
When glazing is installed, a certain percentage of light is lost due to glass thickness, glass reflection, glass coating and construction. The light transmittance or light transmittance of a glass indicates as a percentage how much visible light passes vertically through the window glass:
Float glass allows 85-90% of light to pass through.
Double-layer insulating glass with a heat-insulating coating lets 80% of light through.
Depending on the version, sunshade glass only lets 50-70% of light through.
Total energy transmittance (g-value)
The larger the glass surface of a window, the more natural light and solar heat can enter the room.
The g-value shows how much direct solar radiation and heat can pass through the glass. Especially in cold seasons, solar energy can help heat the room. In summer, this can lead to overheating, especially on the south side. This is why the g-value is particularly important for solar control glass. The lower the g-value, the better the sun protection. The best solar control glass has a high light transmittance and a low g-value. This value is usually between 0.25 and 0.5. 25% to 50% of the radiant energy comes from the glazing. For comparison, the g-value of ordinary double glazing is 0.65 to 0.70.
Thermal insulation/energy efficiency: Ug value
The U-value refers to the glazing, i.e. the Ug value (g=glass). The lower the U-value, the better the thermal insulation/energy efficiency of the glazing. While single glazing has a very low Ug value of about 5.9 W/(m2 K), modern glazing with a thermal insulation coating reaches a Ug value of 0.5 W/(m2 K).
Disc structure in millimeters (e.g. 4/16/4)
The pane structure of the glazing package is shown in numerical order, for example: e.g. 4/16/4 is shown. This is a double glazing with two 4 mm thick panes with a gap of 16 mm between the panes. The maximum thickness of the entire glazing depends on the corresponding window profile depth. This is also given in millimeters. The greater the profile depth, the thicker the glazing.
Glass weight
The weight of the glass is affected by the thickness and size of the glass package. Double glazing weighs less than triple glazing. The larger and thicker the window glass overall, the more stable and strong the entire window frame and fittings must be. This is why very large windows with panoramic glass are usually very expensive, as it needs to be made of very strong and lightweight aluminum.
Important values for window glazing
