High rise buildings mainly use reflective glass that is laminated. This glass is designed to be strong enough to resist heavy wind loads usually associated with high rise buildings. The detailed design should also be such a way that it can keep off rain ingress during rainy seasons.
The reflecting ability of the glass enables heat to be reflected back towards the outside, hence maintaining the interior temperatures to be cool.
The need for natural light in offices is very high. This saves on using electricity and improves on the internal ambiance. Glass facade walls enable maximum use of the side elevations to bring in the maximum possible sunlight during the day in the most efficient manner, keeping away elements of weather.
The glass is usually supported on aluminium framing.
Laminated glass is made of 2 sheets of glass with an argon sandwich infill .
These are made to order and fitted on site. Argon gas helps to cut off heat transfer from the sun into the building.
Some windows are triple glazed to increase heat insulation levels. Argon is a very stable gas, with more insulating capacity than air at 67% better performance.
Laminated glass is designed to last an average of 20 years in facades that do not face direct sunlight and 10 years in facades facing direct sunlight.
Over time, a usual defect is when moisture enters into the air space in between the glass panels. This stains the glass and enables argon to escape, hence the glass not performing its heat preventing duties as expected. The solution is to change the glass facade, which is costly. A few companies have come up to repair failed glass facades in Europe.
Differences in temperatures on the same glass surface can result in differential tension which ends up in cracks. This mostly occurs when one part of the glass is shaded while another is experiencing direct sunlight.
Architect Francis Gichuhi Kamau.