Glass is an increasingly popular material in commercial building construction. It’s used on doors, windows, and in the case of high-rise buildings, on the entire exterior envelope in order to enhance the visual appeal and provide unobstructed views. This being the case, what kind of glass is used in high-rise buildings?
The type of glass used in high-rise buildings needs to be very resilient and fabricated in such a way that it doesn’t shatter in case it gets damaged. Additionally, it should be transparent, have high workability, visible transmittance, lower U-value, and be completely recyclable.
The rest of this article will focus on the factors that affect high-rise buildings and what to consider before installing the glass.
The Glass Used in High-Rise Buildings
High-rise glass is made up of two pieces, each 6mm (a quarter-inch thick), and is separated by a half-inch air space, creating a one-inch thick unit. The glass is factory-made with double seals that allow for desiccated air inside (dry air) to prevent fogging. Where the climates are very cold, the spaces are packed with argon.
High-rise building glass is heat strengthened instead of being tempered or laminated because tempering creates additional stress that compromises optical quality. Tempered glass is customarily marked with a dot on specific panels to enable firefighters to identify them in case they need to break-in.
Major Concerns of High-Rise Buildings When Installing Glass
High-rise buildings are more complex than low-rise commercial buildings and residential buildings. For this reason, contractors need to keep in mind various concerns and factors that could affect them and the kind of glass they install. Some of these major concerns of high-rise buildings include:
As a building reaches great heights the effects of wind become more significant. Buildings that are closer to the ground are not exposed to these wind conditions because the wind is disrupted by hills, other buildings, and trees. However, tall structures face the unobstructed, full force of the wind from all sides: front, back, and sideways.The wind that hits the glass head on pushes it inwards, while that which hits it from the sides creates a low pressure that could suck out the glass. These suction forces could be tougher than the head-on pressure. The suctions and pressures caused by the wind travel down the high-rise building at high speeds, creating high forces at multiple locations.
Heating, Ventilation and Air Conditioning (HVAC)
Heating, Ventilation, and Air Conditioning (HVAC) systems are responsible for the heating and cooling as well as the airflow and lighting of high-rise buildings. Tall buildings present a unique challenge for HVAC equipment due to extreme energy expenses. The interior heat mass is immense; therefore, air conditioning needs to remain constant even during winter. Besides the internal heat mass, a large proportion of high-rise buildings are usually exposed to the sun with nothing to block it during summer.
Here is a video about energy efficiency for high-rise buildings:https://www.youtube.com/watch?v=4W6fZiGT75Y
Safety During Operations
Another important thing to consider regarding glazed structures is how they will be maintained, re-glazed, and cleaned. The decision depends on the proposed glazing strategy, whether internal or external.
- External strategy: A special plant, for example, abseilers or other roof-top access machinery, will be required.
- Internal strategy: In this case, the choice and design of the window will be critical. There are numerous kinds of hinges that allow for cleaning and maintenance of the external glass pane from inside the room, hence providing safety. Some of these options include tilt and turn or side hung.
- Cleaning: Outward opening of glass windows creates an element of leaning out to carry out any operations. Hinge mechanisms can be difficult to operate when they become rusty or sticky due to a lack of regular maintenance. This may pose safety hazards with high-rise buildings, especially when windows are caught by a strong wind. The force could even rip the hinges off.
- Re-glazing: Re-glazing safely inside the room is only possible if the window can open into the room or it has internal beads. Beware of internal beads that require glass to be turned at an angle for them to move inwards or have to be moved outside.
- Balcony doors: Outward opening doors that lead to balconies on high-rise buildings still pose risks like the windows due to the wind. Since doors are heavy and big, the risk is even higher because the forces are more intense. Consider those that open inwards or the sliding doors to promote safety during operations.
Attributes to Consider When Specifying Glass for High-Rise Buildings
With the complexities faced by high-rise buildings, whether you’re planning on building or replacing the glass on windows and doors, there are key attributes that need to be considered. They are:
Thermal Performance and Lighting
High-rise buildings glass needs to be tinted or coated to reduce heat gain from solar while staying insulated to retain heat. Also, it needs to create a balance and control how much light flows in while protecting against UV rays and infrared energy. Double-glazed units are typically manufactured with an air space between the panes which can be filled with inert gases, hence enabling insulation.
Normally, glass panes have a natural greenish tint unless they are low-iron, a more clear glass with less tint. However, several coatings and tints can be added to the glass, from blue, bronzed tones, and smoky grey.When replacing the glass on windows in high-rise buildings, it is crucial to match the tint/color. Although some buildings allow for the glass to be mixed and matched with various shades, it is best to maintain the consistency of this detail.
Glass thickness impacts the strength and light transmittance of high-rise building glazing. Glass is heat-strengthened in a destructive, heat-soaking test. This test determines if there are any faults, such as any inclusions of nickel Sulphide in the glass that might cause it to shatter immediately when exposed to stress. If it survives the test, this means it is safe for use.
The outer panes of glazed units are laminated, creating a polymer interlayer between the two glass sheets. With this, the glass acquires extra strength, and in case of any physical failure, it can still be retained. Falling from over three stories is dangerous, but even if it becomes fractured into several cubes, they will still be stuck together.
Glass can be visually appealing, but security is also something that should be taken into account. Whether it’s a commercial or apartment high-rise building, privacy is essential. Glass can be fully or partially frosted to increase privacy. Frosted, tinted, or translucent outer glass can also be used to reduce distractions from the outside.
Regardless of budget, one thing that should never be compromised is the quality of the glass used and the installation. If not properly installed or low in quality, glass can lead to serious safety hazards due to accidents. Low-quality glass easily cracks and can shatter during installation. This will result in extra expenses due to replacement. It’s important to check the specifications when purchasing, even during future replacements.
Glass has been embraced by high-rise commercial builders. Not only does it create a visual appeal, but it’s also less costly and energy-efficient than other materials. High-rise buildings use heat-strengthened glass instead of tempered or laminated glass to help withstand pressure and suction forces from the strong winds. Also, it allows for the retention and insulation of heat.
Some of the major concerns when designing and building with glass include weather performance such as wind, HVAC, and safety during operations. Consider attributes like thermal performance, color, privacy, quality, lighting, and durability before construction.
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