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By 2025, the world will likely see 35 more megacities with over 10 million people, many of them living in high-rise buildings ranging from 12 to over 100 stories. When the daily routines of up to 1,000 residents coincide, many litres of water can be discharged simultaneously into the drainage system creating pressure spikes. The network of pipes with its hundreds of traps has to cope without any risk of bad odours or bacterial contamination, which calls for the innovative systems developed by Aliaxis High-Rise Building Solutions.

The impact of a skyscraper’s great height on its water supply and drainage systems is often overlooked. Residential buildings have more sanitary facilities than office buildings: bathrooms, toilets and kitchens. At peak hours, all of the fixtures in the building can be used at the same time, causing a substantial increase in negative and positive pressures in the often complex layout of pipes. Rainwater drainage is a further challenge: during heavy rainfall, a huge volume of water collects on balconies as well as the roof and it all needs to be drained off without the residents noticing.

Rising to the challenge

Property developers look for drainage systems that are sufficiently innovative and reliable to rise to these demands. They also have to be efficient to install and take up as little space as possible so as to maximise usable residential space and make the apartments more attractive to the buyer.

The Aliaxis High-rise team is well-placed to meet all these modern requirements for feasibility, comfort, safety and affordability. Drawing on the range of products available from Aliaxis businesses worldwide enables them to provide a complete package for water supply and drainage in high-rise buildings as well as to find solutions for rainwater drainage.

At peak hours, all of the fixtures in a high-rise building can be used at the same time, causing a substantial increase in negative and positive pressures in the often complex layout of pipes.

Invisible and indispensable

People are used to taking this invisible yet indispensable part of their lives for granted. But meeting the drainage challenges of high-rise apartment buildings means taking into account a great many more laws of physics. The water supply and drainage system are made up of an entire network of smaller branch pipes per flat, and they are all connected to large vertical stacks, of which there can be several in a large building. Connected to the branch pipes are the drainage pipes from toilets, dishwashers, baths and showers, often being used at the same time during peak hours. As wastewater from a flush is falling vertically it drags along air and when this airflow is interrupted by another flush a pressure differential occurs. The long pressure relief time in a high-rise building will cause the traps in an apartment to be sucked dry or blown out.

This not only causes bad odour problems, but can also be a health hazard, because it provides an entry point into the home for bacteria and viruses from the main drainpipes.

Innovative systems

Traditionally, pressures are regulated via a secondary ‘dry’ pipe with its air ventilation conveyed upwards through the roof. However, the higher the building, the wider the ventilation ducts have to be, not only taking up too much space, but also making their pressure differences extremely difficult to regulate, including the water level in all the different traps.

Aliaxis offers two innovative solutions for high-rise building drainage: the single stack system with stack-aerators and the active drainage ventilation system with P.A.P.A.s (Positive Air Pressure Attenuator) and AAVs (Air Admittance Valves). The first system works with a special fitting, a stack-aerator, to connect the horizontal and vertical pipes as an alternative to a T-branch fitting. The stack-aerator allows the air pressure in the drainpipe to remain stable and eliminates the extra ventilation pipe. This solution not only outperforms the conventional system in terms of flow capacity, but also saves space and therefore costs.

The Aliaxis High-rise team is well-placed to meet all the modern requirements for feasibility, comfort, safety and affordability for high-rise living.

The Active Drainage Ventilation works in a different way: The P.A.P.A. acts as a kind of overpressure vessel that attenuate positive pressure spikes whilst the AAVs attenuate the negative pressures. The P.A.P.A.s and AAVs can be placed at the exact point of need, the spot where a problem with pressures could potentially occur. The advantage of this product is that it can be deployed in new buildings as well as resolve specific problems in existing buildings.

Outdated standards

The relevant international standards have not kept pace with reality: techniques are still being used that comply with standards up to 50 years old and generally designed for use in buildings of 10 to 25 stories at most. Today’s engineers and architects have little choice but to overdesign their drainage systems, providing for excess capacity just to comply with safety norms.

However, Aliaxis systems are not only innovative, but our high-rise team offers the expertise of many years’ research to contribute to the process of designing a tall building so our technical solutions can be deployed to function at optimal capacity.

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