When considering the virtues of today's tall buildings, is height all that remains?
This thought-provoking question was posed by Ole Scheeren, partner with Office for Metropolitan Architecture, Rotterdam, The Netherlands, to more than 400 A/E/C professionals attending Council on Tall Buildings and Urban Habitat's 7th World Congress in New York last month.
Scheeren said so many tall buildings are one-dimensional and empty of quality content, and end up isolating instead of engaging the public.
Scheeren presented several alternative models to the traditional skyscraper that maximize "social potential" by employing inventive configurations. The massive headquarters for China Central Television currently under construction in Beijing, for instance, features a parallelogram-like form that provides multiple social "touch points" with the public, as well as an innovative circulation pattern for occupants, visitors, and tourists that is essentially an "endless loop," said Scheeren.
Building Teams for several of the world's tallest buildings outlined their design strategies for fire/life safety and emergency response.
Mega-towers like CCTV and the Burj Dubai in Dubai will have decentralized building cores to provide multiple safe evacuation routes. Burj Dubai will have three separate stairwells (one in each wing), as well as four strategically placed refuge areas that will be accessible by the stairwells.
CCTV follows the model employed at Petronas Towers in Kuala Lumpur, Malaysia, with twin, freestanding towers connected near the top. This permits occupants to flee the affected tower by traversing to the second tower and then move safely downward to street level.
At the 49-story Seven World Trade Center tower in New York, due to open in March 2006, architect Skidmore, Owings and Merrill, has designed a "hardened" central core that will ensure a clear vertical path to safety. Encased by reinforced cast-in-place concrete shear walls, the core includes two extra-wide stairwells (72 inches), an expansive fire- and smoke-resistant refuge area on each floor, two-hour fire-rated doors, pressurized stair shafts, bonus space (approximately 30×48 inches) at each stair landing for rescue assistance, lighting systems with three power sources (normal use, emergency mode, and battery backup), and phosphorescent paint strips throughout the core to improve visibility. In addition, the stairwell doors have been situated so that they open to the descending side of the stairwell to facilitate traffic flow, and proximity egress signs and marking systems near the stairwell doors have been placed less than two feet above the floor to maximize visibility.
Freedom Tower will have even more bells and whistles, according to Carl Galioto, FAIA, partner with SOM. Novel features include a dedicated stairwell for firefighters and a robust emergency response elevator, designed with a hardened dedicated enclosure, pressurized hoistway, direct access to the emergency responders' stairwell via a pressurized vestibule, emergency backup power, and water-resistant equipment.
Galioto said the standard passenger elevators will also have emergency backup power and water-resistant equipment, which will allow first responders to use the elevators to assist with evacuation efforts.
"The intention is that the first responders will be able to use the elevators to supplement the stairs, not in lieu of the stairs," said Galioto.
Prohibited by most national and local building codes, the concept of using elevators to evacuate building occupants, especially handicapped and elderly people, is currently being evaluated and developed by group of industry organizations led by the National Institute of Standards and Technology and the American Society of Mechanical Engineers (BD&C May 2004, p. 5).
Robust, hardened cores aren't cheap, said Galioto. The wider stairwells alone decreased the amount of leasable floor area by 1–2% at Seven World Trade Center.
"Hardened cores are not appropriate for every building," said Galioto. "Teams need to assess the safety risk factors, such as location, building function, and height, and then apply these strategies with discretion."
Galioto said one way jurisdictions can encourage developers to include hardened cores and safety areas is to deduct these spaces from the zoning areas so they can build more leasable area.
Other interesting notes from the event:
CTBUH is teaming with the National Fire Protection Association to develop a rating system for building fire and life safety. CTBUH chairman Ron Klemencic said the system will be based on a scorecard approach, much like USGBC's LEED rating system, that will allow Building Teams to score their buildings based on a set of criteria.
While Building Teams are much more intune with security design these days, Eve Hinman, PE, president and founder of Hinman Consulting Engineers, San Francisco, said there's room for improvement. Placement of bollards is a common miscue, according to Hinman.
"Bollards need to be placed at the curb line, but I often see bollards set back off the street or sidewalk," said Hinman. Other mistakes include breaks in the bollard configuration and the use of certain planters that may look daunting, but "can be moved easily."
Valentine A. Lehr, PE, partner with Lehr Consultants International, New York, is experimenting with an "integrated" domestic water supply/fire sprinkler system in high-rise projects in New York and Dubai, whereby the fire sprinklers will tie into the domestic water piping throughout the buildings.
Common in Australia, this approach not only reduces upfront plumbing infrastructure costs by 30–35%, it also results in a more reliable sprinkler systems, according to Lehr.
"There's no stagnation with this method," said Lehr. "Every time someone flushes a toilet or takes a drink of water, the sprinkler system is tested."
In comparison, typical sprinkler systems have dedicated water supply lines that can go untested for years. "With the same water sitting in there so long, who really knows if the system will work," said Lehr.
Lehr also talked about next-generation fire/life-safety strategies that, through the use of technology, will drastically reduce long delays between the four critical milestones of fire/life safety: the event, detection, suppression, and evacuation. Lehr said by integrating a building's fire detection/alarm, communications, data, mechanical, and security systems, buildings can detect and even predict precursers to disasters.
The latest security cameras, for instance, can detect smoke, gauge temperature, and even count the number of people within sight. By integrating the cameras with the other critical building systems, the cameras essentially become another fire detection device that can automatically sound the fire alarms.