Glass
Facts
The
Good.... The Bad.... The Ugly
Read this fascinating insight into how glass works.
The
Good
Glass has been used since the
days of the Romans to allow natural light
into our buildings.The increasing use of light in architecture and workplace design means that glass has become a major feature of the modern day building. Discover why glass is transparent.
However, glass does create certain problems too...
The Bad
Heat as well as light enters the building resulting in discomfort of staff and higher air-conditioning costs. Find out more.
Privacy is reduced, which puts your possessions on display.
Glare is uncomfortable for screen users and reduces staff productivity.
and because glass is easily broken it can get ugly...
The
Ugly
Glass is easily broken and
becomes the weak point in your security. 36%
of security breaches is through the glass.Toughened glass can spontaneously break for no apparent reason. This becomes a danger in tall buildings. Why does toughened glass suddenly break?
During a bomb blast, shards of glass can fly through the air at speeds up to 40 meters per second and become a potentially lethal threat to staff and visitors.
Just why is glass fragile compared with other building materials?
How
is glass made?
Sand,
soda ash and lime are heated up to very high temperatures in a furnace
to become a great syrupy mass. When allowed to cool it becomes glass,
which retains many of the properties of a liquid.
Why is glass
transparent?
The
materials used for glass cool and solidify. However, the resulting
glass retains a very random molecular structure. The
rather random and loosely spaced molecules in glass allow much of the
visible and ultra-violet spectrum of light to pass through.The greater the randomness of the molecular structure, the easier it is for the light to pass through. This is why you can see through most liquids and gases.
In contrast, solids like wood, metal or stone (eg. bricks) have a regular crystalline lattice structure, which makes it very difficult for light to pass through.
[ back to "The Good" ]
Why do glazed buildings become hot?
The Greenhouse Effect.
Visible light and ultra violet light pass through the glass. When the light hits an object it is either absorbed, scattered or reflected. The energy from the light is released as heat.
As glass is not a good conductor of heat, the temperature in the room builds.
Window films can be used to reflect light and its associated energy to prevent a build up of heat inside the building.
[ back to "The Bad" ]
Why does glass break?
Ahh, this is a controversial one!
Firstly, glass is Brittle.
Glass is brittle because it does not have good large-area orderly crystalline structure. If it did, it would be like sheet metal steel, where it dents and deforms instead of shattering.
When the stress exceeds the strength of the glass it breaks.
Modern buildings tend to use toughened glass, which avoids some of the serious injuries that may occur.
Residential properties and older buildings contribute to serious injuries when glass breaks. Find out more about glass injuries and how they are most commonly sustained.
Secondly, glass breaks due to heat
Applying a temperature change to one side of the glass causes expansion or contraction to occur. Because glass is not a good conductor, the glass does not expand or contract evenly across the pane.
Because glass is brittle, the stress imparted causes it to break, shatter or explode.
It is important to chose the correct window film for glass as some absorb heat. It is important to work with a reputable company... like us :-)
[ back to "The Ugly" ]
Spontaneous
Breakage of Toughened Glass
Small
impurities find their way into the glass from the manufacturing process
of toughened glass. The most common is small shavings of stainless
steel (nickel sulfide inclusions) which increase the internal stresses
in the glass. When the stress exceeds the strength of the glass it
breaks.also
Every effort is hopefully made to avoid damaging the glass during installation. However, small nicks and chips can occur from tools or around fastenings. Over time, as glass expands and contracts stresses develop around the damaged unit. Eventually the entire toughened glass unit can break.
This is a serious issue when the glass is part of a window at height.
[ back to "The Ugly" ]
