In the construction business, the initial functionalities of glass – lighting, ventilation and aesthetics, for painted glass – have diversified over time. The advancements in glass manufacturing processes and the emergence of new assembly techniques have increased the importance that glass plays in modern architecture.
Nowadays, designers have more freedom to build true edifices of light, which combine aesthetics with the increased need for modern confort.
The assembly technique used for curtain walls and the wide range of glazing (reflective coating, low-emissivity, solar radiation control etc) have helped glass become an ever present material for facades.
Due to the fact that glass covers wide areas in these structures, it plays a decisive role in aesthetics, thermal and acoustic insulation, but also when reduction in the construction and maintenance costs are considered. This is why choosing the type of glass is an important step.
Thermal insulating system
The solution that best fulfills the need for thermal and acoustic insulation, security and transparency is the thermal insulating system. Actually, it's a structure obtained through sealing two sheets of glass of equal or different thickness. The thickness varies depending on the surface of the glass and its location (inside/outside). For curtain walls, the outside glazing must be at least 6 mm thick.
For the thermal insulating systems, any combination between the various types of glazing is possible.
Types of glazing
Float Clear. The 4 mm thick glazing is the most commonly used window in classic joinery. For curtain walls, a thickness of 6 mm is mostly used.
• Low-E.
It is obtained by coating float glass with an invisible layer of metallic oxides and alloys. This reduces, during winter, the heat loss by reflecting it inwards. Due to the thermal properties at a low price, low-E glass is the most commonly used glass for thermal insulating systems in combination with a 4 mm float.
• Tinted glass (PARSOL)
It is produced by adding colourants to plain basic glass. The most frequently used colours are copper, gray, green and blue. The colour depth depends on the thickness of the glass. The colour increases the solar heat absorption properties of the glazing, most of this heat being reflected to the exterior.
• Reflecting glass
It dampens solar radiation, thus reducing solar heat transfer and consequently diminishing air conditioning expenses. It is obtained by coating the glass with metallic oxides which enhance the 'mirror effect'. The most frequently used colours are copper, silver gray, green and blue.
• Opaque glass
It is obtained by sand-blasting clear glass (the glass is washed with a jet of pressurized sand) – the most common procedure – or through controlled corrosion. In the thermal insulating systems, the sand-blasted side is facing inwards.
• Decorative glass
It is imprinted with various patterns. It is obtained by rolling the hot sheet of glass between 2 metallic reels, engraved with the negative image of the decorative pattern.
• Safety glass
It is obtained by thermally treating float glass (the glass is heated to a high temperature and is then rapidly cooled). The resistance of the glass is hereby increased approximately 4 times. In case of shattering, the glass shards are small, blunt and not dangerous. Security glass allows no further processing.
• Laminated glass (duplex)
It is obtained by using a 0.38 mm thick PVB foil to glue 2 or more sheets of glass (of equal or different thicknesses – which enhances the acoustic insulation properties). Even if the glass breaks, the shards remain on the foil.
• Armored glass
To increase the safety, a wire mash is inserted in the glazing during the cooking process. Armored glass is harder to break and the shards remain glued to the structure.