In my last article, we spoke in general about what an aperture consisted of and went into further detail which materials are available in the market. Today I am going to focus on another crucial aspect of an aperture, glass.
Glass has the largest surface area in a window or door, therefore, after the profile, glass holds a pivotal role and makes part of the six choices that a client has to consider during purchasing. The majority of heat losses and sound insulation failures may be contributed to glass, not to mention the security options available.
In a basic format, glass can be either float, laminated or tempered. Float glass is referring to the standard type of glass, which although can be coated for thermal efficiency, it fails to thick the safety and sound insulation boxes, of course, this is the cheapest and considered as entry level. In some countries, this type of glass cannot be used when a glass pane is larger than a certain size.
Laminated glass consists of a multi-layered glass, usually divided by an EVA or PVB film. The films offer both a security function, meaning that when a pane is broken, it stays in place, while it provides ultraviolet filtration to prevent secondary heating. In some cases, primarily when the layer is doubled, this glass is also used for specific areas that require further sound insulation.
Tempered glass is considered a safety glass because when it shatters it falls into small pieces. The process involves the heating up of an ordinary float glass where glass molecules are compacted and increase the strength of the pane. This types of glass have various uses, from furniture to glass railings and facades such as high rise buildings. Where the glass pane is challenging to be replaced logistically, this treatment can be enhanced with a Heat Soak Test, where the glass is processed to a stress test to determine whether there are any imperfections in the glass that might cause thermal shock.
Then there are the treatments which in our case can be divided into three parts, solar, low emission and reflective. The latter type is typically used for design and to create privacy in large format envelopes, again a typical case is a high rise building. Reflective glass can also be considered an architectural feature of a building. On the other hand, low emission glass is used for colder climates which leave solar radiation penetrating internally but prevent the ray from penetrating out, creating a comfortable effect, especially on a beautiful winter day. To the contrary, solar glass is used in hotter climates, where the film filters infrared rays so what penetrates to the inside is left at bare minimum, while it controls the internal temperature as the user intended, resulting in better energy efficiency.
In some countries, there is also self-cleaning glass, but this requires continuous rainfall so the broken particles can be washed naturally. As you might be noticing, there is a lot of mix and matching involved. Keeping in mind the six choices, one has to evaluate his or her requirements and ask their supplier of choice for guidance, especially since different glass manufacturers supply specific regions.
During my next article we will go into further details about the fittings, thus what are the types of apertures one can have and their advantages and disadvantages.
Fabrizio Gerada.
