HEATING, VENTILATION & ENERGY EFFICIENCY


Balance – the key to eliminating odours in tall buildings


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Ventilation and pressure challenges make high-rise buildings particularly susceptible to odour complaints. Here Steve Bamforth, UK Strategic Project Director at Polypipe Building Services, explains the pressure points of ensuring high performance of safe, robust, and hygienic drainage systems


ur city skylines are reaching higher. Manchester is a prime example of a city aiming for the heights with plans to build the highest residential block in western


Europe. Meanwhile, in London, the annual Tall Buildings Survey revealed that plans for 583 buildings with over 20 storeys are currently in the pipeline. While tall buildings offer numerous benefits, particularly in terms of meeting housing demand, they’re also technically complex and highly regulated. Now formally classified as High-Risk Buildings (HRBs) under the Building Safety Act, their designs demand rigorous compliance to pass Gateway 2 and proceed to construction.


And the scrutiny doesn’t end there. Further legislation, such as Awaab’s Law, which primarily affects social housing, will soon require landlords to address health and safety issues, including drainage, within 14 days – or less if the problem poses a significant risk. This tightening regulatory environment leaves the industry with little room for manoeuvre. System design for tall buildings must not only perform; it must be proven, safe, and reliable.


Maintaining equilibrium


A frequently overlooked challenge in tall and multi-occupancy buildings is the hidden dynamics of managing air pressure within drainage systems. Poorly balanced air pressure can manifest itself in several ways including water pooling, cracks in walls and foundations, flooding and damp or musty odours. In particular, the drainage systems within tall buildings must be able to cope with frequent. high-volume discharges of wastewater


across multiple levels. This creates both positive and negative pressures within the system. If these forces are not carefully balanced, the results can include smells escaping through appliances, dry traps, and structural cracks as air is forced or drawn to places it shouldn’t go. Positive pressure builds when water changes


direction quickly, and if it is not managed correctly, the pressure can push air through traps and joints, releasing foul gases. Traditional solutions like secondary vent stacks can help to manage positive air pressure, but they need careful sizing and placement. Advanced solutions, such as the Terrain Positive Air Pressure Attenuator (P.A.P.A®), which is a large reactive bladder that is placed at specific points within the drainage pipework, counter this by absorbing positive pressure surges and releasing the air slowly and safely, thereby maintaining the system’s equilibrium. On the other hand, negative pressure must also be managed. Negative pressure can be caused by rapid wastewater movement (like multiple simultaneous toilet flushes) which creates a vacuum. This can pull water from traps, breaking the water seal.


In these situations, air needs to be released into the system without disturbing the pressure balance. To address this, Air Admittance Valves (AAVs) can be used in more sensitive or high-risk areas, such as at the end of a public toilet run, to allow air into the system while maintaining equilibrium. However, for complex buildings, air pressure can be better regulated by a Polypipe Terrain Pleura valve, which is a high-speed reactive AAV that is placed strategically between appliances to respond to transient air fluctuations and ensure immediate pressure equalisation. When it comes to drainage systems in tall buildings, maintaining the right air pressure balance is absolutely key to performance.


Competence is crucial


But air pressure isn’t the only potential cause of foul odours resulting from drainage problems. Often, issues can result from poor workmanship. For example, leaking joints are a common cause of odours. Every seal in a system is a potential leak point and, if the joint is installed incorrectly, thermal movement could lead to cracks, bursts, or odour release. To prevent this happening, expansion fittings need to be correctly installed to allow for thermal movement without compromising performance. And faulty joints aren’t the only culprits. A common problem when it comes to drainage is patchwork systems. In some instances, designers and installers will mismatch components that are different sizes or come from multiple manufacturers. For drainage systems in particular, properly matched components are crucial because not all parts are manufactured to the same standards and any mismatch can cause leaks, smells, noise and other health hazards. Having competent consultants, designers and installers working on drainage systems is critical. Because while bad odours are unpleasant in themselves, they can also pose risks to health and safety, particularly in buildings such as hospitals and care homes. This is because a dry trap can become a conduit for harmful


12 BUILDING SERVICES & ENVIRONMENTAL ENGINEER JULY 2025


pathogens that can circulate throughout a building and spread disease, particularly amongst the vulnerable. For this reason, maintaining a functional water seal is not just about creating a pleasant and comfortable environment, it’s critical for hygiene and safety. Innovations such as antimicrobial additives in trap materials can help to mitigate these risks, but they need to form part of an effective design and be installed correctly.


Collaboration counts


Manufacturers can play a key role in reducing these risks. At Polypipe Building Services, we support consultants and contractors by offering fully tested, prefabricated pipe sections and ready-made connectors, which help to streamline installation and improve consistency. These system elements are delivered to site fully fabricated and air-tested, significantly reducing the chances of component mismatch, faulty joints, or pressure issues. Training also plays a critical role. With


regulations evolving and a shortage of experienced installers, the sector must collaborate more openly, share knowledge, upskill teams, and develop good practices to prevent recurring problems.


For us, this means working closely with the


entire supply chain – from consultants and specifiers to contractors and installers – to ensure that drainage systems are not only technically compliant but practical and reliable in real-world conditions. Because more often than not, drainage failures are avoidable; and the right products, the right planning, and the right people make the difference. Ultimately, eliminating odours in tall buildings is about more than just smell. It’s about balancing airflow, managing pressure, and designing systems that are robust, resilient, hygienic, and safe. By focusing on smarter system design, utilising tested solutions, and adopting better site practices, the industry can ensure that today’s tall buildings are not only a visual spectacle, but they also make a good impression on another sense.


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