Tall-Building Experts: No Easy Path to Truly Sustainable Supertowers
A book is expected in about six months. "It will take 250 pages to explain the findings," said Smith, who was the design architect for the world's tallest building, the 828-meter Burj Khalifa in Dubai, when he was at Skidmore, Owings & Merrill.
Smith currently is designing the planned one-kilometer-plus Kingdom Tower in Jeddah. "If we are going to continue to do supertall buildings, we need to produce power to be sustainable, not just reduce energy usage," he said.
One area that shows promise for improved sustainability is vertical transportation. Braking energy can be regenerated into electricity, standby energy can be minimized, and cars can be made lighter.
Four years ago, one elevator maker introduced a more sustainable system that is designed to speed construction. Called the KONE JumpLift, the self-climbing hoist uses a tower's permanent hoistway and a temporary machine room that "jumps" with the hoist.
For a 70-story building, JumpLift can shorten the construction period by 300,000 to 400,000 hours, said Johannes de Jong, chief technology officer for KONE Industrial Ltd., Hyvinkaa, Finland. The system costs more than a conventional construction hoist, but 80% of the elevator material can be permanent.
The hoist, usable when the building is 20 m up, allows the lower floors to be enclosed and finished sooner, said de Jong. Hoisting takes place inside the building, a safer practice that results in fewer work days lost to high winds and other bad weather. Also, cabs move more quickly, reducing worker waiting and travel time.
To best reap its advantages, JumpLift planning should be done during the design phase. "I would like developers to put this into the contractor's specs," said de Jong. "If not, the contractors will use it as risk mitigation and the developer won't see the financial advantages," he added.
Incorporating JumpLift into a job requires careful planning and coordination with the building team. "If the decks aren't lifted, we are stuck," said de Jong.
The system has been used in Asia and Europe. Last year, it was approved for use in North America.
