Given their particularly complex design and construction, towers often involve numerous constraints requiring advanced expertise. Confirming its experience in this field, setec group won the Grand Prix National de l’Ingénierie (French national engineering award) in October for the Paris Law Courts, and will also help build the new Montparnasse Tower.
After the Paris Law Courts, setec is launching into another major project in the French capital: the metamorphosis of the Montparnasse Towers. Created in 1973 and often criticized by Parisians, this 210 m high building is now undergoing a metamorphosis thanks to the decision of its co-owners, convinced by the architectural project proposed by Nouvelle AOM. The tower will not be destroyed to make way for a new building. Instead, it will be transformed “from an opaque, singlefunction, asbestos-containing structure with high energy consumption, to a light, low-carbon, energy-efficient tower capable of offering new uses,” according to Mathurin Hardel, one of the agency’s five architects, in Le Moniteur.
And new uses mean new regulation, especially for fire prevention and safety. “Buildings are considered high-rise when they are over 28 m in general. With these buildings, the classic approach of fire fighters entering a building from the façade is not possible, ” explained Eric Mangini, fire prevention officer at setec bâtiment. “We need to change strategy and enable firefighters to work from inside the building.” This is especially important when the tower, which was once only offices, is preparing to house several high-occupation activities and will need to comply with new 2011 regulation. “The Montparnasse Tower is a real security challenge since the number of occupants will jump from 7,000 to 12,000 ” revealed Eric Mangini. In addition to offices, the building will house cafeterias on different floors, a hotel between the 42nd and 45th floors, a viewing point with a terrace and greenhouse, and above all, a fitness center, crèche, business center, events venue, and more.
In the design stage and throughout the rehabilitation project, setec bâtiment’s fire prevention and safety department will assist the engineering and construction team and coordinate security measures.
setec is also bringing its expertise to another major challenge: energy performance. “Digital modeling allows us to produce accurate dynamic thermal simulations which facilitate dialogue with the architects,” remarked Eric Blanc, technical director of the thermal engineering, energy and building physics (GTEP) department at setec bâtiment. The façade of the Montparnasse Tower was designed like a chessboard with wind sensors to optimize the natural ventilation and lower the building’s energy consumption. The expected performance gains include 70% energy savings in ventilation. Similarly, the choice of glass for the façade will be key to reducing the use of artificial light. But Eric Blanc is convinced that “in the future, we will need to change the form of the building for more efficient air collection, more natural light and more space allocated to social areas.” This is already the case with the Sisters Towers by Christian de Portzamparc, a setec project combining different spaces in the same complex.
Finally, one area where user distribution is critical is the elevators in high-rise buildings. Calculating traffic is particularly complex when a tower houses different activities. For Montparnasse Tower, we have made 400 simulations, each over a quarter of an hour, at different times of day and in rush hours,” explained Luc Moraillon, who is in charge of the electromechanical and electricity team at setec bâtiment. The tower’s 59 levels will be served by 27 elevators, offering office workers a wait time of under 30 seconds. The location and performance of the elevators can make a real impact on tower design and lead architects to modify their plans. The physical features of the building, fire prevention and elevator use are good examples of the fruitful collaboration between setec’s engineering expertise and the vision of architects on major-scale projects.