Fire protection concept included. Calculating variables is difficult because of their diversity
The Grosspeter tower in the center of Basel has everything to become a new landmark for the metropolis on the Rhine. The building, which is almost 80 m high, will be used for different purposes: 10,000 m2 will be used for offices and commercial buildings.There will be a hotel and an underground multi-storey car park. This necessarily requires particularly high standards for ventilation engineering, as well as for smoke and fire protection. An additional complication is that potential tenants for the office spaces must be offered flexible layouts and variable interiors. In particular, in case of fire, the smoke protection system must be designed in such a way that it functions reliably independently of the future internal layout, allowing a smoke-free escape route of the building.
"Intervention smoke extraction" for underground parking
The underground car park, which has a sprinkler system, is subdivided into four fire / smoke extraction sections with fire-resistant doors. The smoke is mechanically withdrawn from these sections via the roof with an eightfold air exchange using simultaneous natural airflow for the replacement of fresh air. The goal is "intervention smoke extraction". This allows immediate evacuation of users and rapid deployment of firefighters in the central parking lot.
The concept for the mechanical smoke and heat extraction installations includes the underground parking garage, the required fans, silencers and smoke exhaust valves (fresh air replacement and exhaust air), as well as the correct warning system including CO and NO2 sensors and transparent warning signs. The fans must be certified for 120 minutes at 400 ° C according to EN 12101-3.
Reliable calculation is difficult The core of the fire safety concept for the tower itself is a smoke protection system for the fire escape with associated lock zone. Both actively maintain an overpressure. An outflow, a fire brigade lift and replacement of fresh air via two passenger lifts complete the concept. Outflow is achieved with smoke discharge valves in the user area, supported by a fan on the roof. In addition, a pressure cascade prevents smoke from being built up again in the stairs. A particular challenge in the design of the smoke protection system for the Grosspeter tower was the varied number of variables that occur during a fire:
• cumulative air leaks from the external walls, leaks through the elevator doors • the doors on the ground floor that are fully opened in the event of a fire • the pressure ratio between the user areas and the fire escape.
Reiner Kelch, system and application manager for smoke protection systems at Systemair, says: "The many variables and their interactions make it almost impossible to calculate reliably, even with the help of integrals, instead of which, because of safety margins, ordinances are generally reached that are economic reasons can not be implemented, making the practical experience of a broadly oriented supplier all the more important.
A typical example is the installation of a special air curtain at the door between the closed zone and the basement. Thanks to a pressure difference of 10 Pa, this prevents the fire escape with smoke fumes - even if the main entrance is permanently open. This is considerably more cost-effective than installing the larger air supply fans that would otherwise be needed.
Project: Grosspeter Tower, Basel, Switzerland
Concept: Fire safety concept for high office buildings
Service: Mechanical smoke and heat extraction systems
Product: Type AXC 560 (F) and 1250 (F) fans, silencers, smoke exhaust valves
Planning: Gruner Gruneko AG , Basel, Switzerland
Implementation: Meier-Kopp AG, Reinach, Switzerland