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October 26, 2023


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Proven Smoke Protection for Stairwells – What More You Should Know About Pressurisation Systems?

New regulations in the UK have made second stairways mandatory in new high-rise buildings. But is this sufficient? Experts say that a single stairway can be safe with the proper measures. Discover what every fire engineer and HVAC designer should know about the research, design, and operation of pressure differential systems (PDS). This knowledge can be your competitive advantage.

Why Is It Worth Considering Pressure Differential Systems (PDS) in the UK?

Initially introducing new concepts such as pressure differential systems faces skepticism from designers, who wonder“Why should I be the first?” While it might be understandable if we talk about leaping from a high rock into the sea. It’s not if we think about the construction industry. Drawing inspiration from research and case studies beyond one’s borders is crucial. Different regulations, methods for achieving standards, and even prevailing weather conditions result in diverse experiences. It’s worth noting that by sharing experiences, we enhance fire safety.

Pressure differential systems have gained recognition and extensive use as a solution to safeguard stairwells in Europe’s tallest buildings. Research demonstrates that it is the most effective solution for smoke protection in stairwells. Nonetheless, some UK experts harbour doubts about the system’s effectiveness, making it a significant challenge for fire engineers and consultants who comprehend its value to convince the rest of the industry.

What Benefits Does PDS Offer as Stairwells Smoke Protection to Stakeholders?

Much depends on specific needs. The designer of HVAC installations or a fire safety expert will consider various aspects of the system’s operation, while investors or installers may focus on different elements. The system’s specificity, assembly, and operation all justify the implementation of PDS in a facility.

Design and Fire Engineers: Experts in fire protection system design, constantly seeking dynamic and innovative approaches aligned with evolving safety standards. Manufacturers of PDS typically provide additional knowledge sources, advanced technology training, and design support to create cutting-edge yet reliable system designs.

Installer and Plant Engineer: Responsible for commissioning and installation, they rely on PDS for trouble-free installation, comprehensive support, and faster deliveries from a single manufacturer offering a complete set of devices.

Building Owner: In charge of managing building safety mechanisms to maximise safety while minimising operating costs. PDS’s lower costs, high reliability, and state-of-the-art solutions benefit them.

Facility Manager and Maintenance Staff: Responsible for administering and operating building systems, focusing on safety and efficiency. PDS offers cost savings, easy-to-use control systems, and maximum safety with remote diagnostic capabilities.

Challenges for PDS (Based on Over 30 Years of Experience from the SMAY Ventilation System Team)

SMAY experts have completed hundreds of PDS projects including dozens in high-rise buildings, with the tallest building in the European Union, Varso Tower, among them. Their unique blend of expertise has led them to work in United Kingdom, continental Europe, Mediterranean Basin and Middle East, taking into account varying regulations, temperatures, and weather conditions at different locations. They share insights into the most frequently occurring challenges:

  1. Dynamic Wind Load Impact

Wind blowing towards the building affects the pressure inside. It is important that the PDS has the ability to react dynamically to dynamically changing conditions and continuously adapt to the current situation.

  1. Stack Effect

Differences in air density caused by temperature differences create air movement in large vertical spaces, causing uneven pressure distribution. This is one of the biggest challenges of pressurisation systems, as a system designed solely for isothermal conditions can result in insufficient overpressure and smoke suction at one end and too much overpressure and inability to open the door at the other. The solution may be a reversible flow system that adapts the direction of flow to temperature conditions and equalises the pressure over the entire height of the stairwells both in summer and winter, guaranteeing the best pressure distribution.

  1. Risk of failure

Reliability means failure-free operation and quick detection and diagnosis of potential errors. The system should be tested as a whole (all components) over as many operating cycles as possible. But system automation should also monitor all components and automatically test dampers and fans in pressurisation units every 24 hours.

  1. Changing Space Tightness

As a building’s airtightness degrades (aging of seals, new installation holes), manual recalibration of passive systems becomes necessary, creating maintenance challenges. So, again, it is better when the system has 24/7 control and automatically adapts to current conditions.

  1. Space Rearrangement Complexities

Flexibility in shaping the space is key to remaining competitive in the construction market. Rearrangement affects fire scenarios and the hydraulic properties of the building. The flexibility of PDS and its self-adaptability make it easier to make changes. Not all PDS on the market have that possibility.

  1. Design Complications

Factors such as air volume calculations, equipment placement, and other considerations can lead to design difficulties and safety concerns in pressurisation projects.

Why does PDS design need an individual approach for every building?

Proper planning requires accurate identification and analysis of the components that affect the pressure distribution within the protected areas and the flow of air mixed with smoke in the facility.

Several factors influence PDS design, including building height and architecture, fire strategy, planned fire protection solutions, standards, legislation, exposure to weather conditions such as wind and temperature, detailed design assumptions, cooperation with other systems, and budget considerations. Keeping these factors in mind, designers need to make the following choices:

  1. Defining protected spaces,
  2. Choice of system class,
  3. Determination of scenarios and number of open doors,
  4. Determining the method of air release path,
  5. Airflow calculations,
  6. Consideration of the stack effect,
  7. Selection of pressurisation units, including accessories,
  8. Location of equipment, supply and extract points, pressure sensors, sizing of sizers and damper,
  9. Selection of other system components, control systems, and system wiring guidelines.

It’s a lot to consider, but that’s not all. What else? Especially for tall buildings, mathematical analyses or CFD simulations should be carried out to assess whether the system operates effectively under all conditions (stack effect mitigation).

Stay Ahead of the Game!

To learn more and explore real case studies, dive into an example of the research findings and design of a 102-meter building at www.smay.eu/pds/. Use your knowledge of PDS as a competitive advantage for your team.

If you require design or technical training or support for fire ventilation projects, don’t hesitate to contact us at [email protected]. Gain insights from the SMAY team, with their extensive experience from hundreds of completed PDS projects.

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