17 mar 08 | Engineering News-Record
Building sector needs reeducation
By Nadine M. Post
Tall-building designers say their pursuit of sustainable high-rises is stymied by a dearth of performance metrics to validate their green-building system modeling. Skyscraper supporters the world over also are frustrated by the slow pace of production of sustainable buildings and retrofits, especially missed opportunities for sustainable urban planning in the hotbeds of urban development in the desert-dry, oil-rich Middle East. Others call for reeducating the entire buildings sector, globally, to enable green-building production.
These sentiments and others were voiced at the Eighth World Congress of the Council on Tall Buildings and Urban Habitat, held March 3-5 in Dubai. The conference, themed "Tall & Green: Typology for a Sustainable Urban Future," was attended by 965 building professionals from 42 countries, a record for a CTBUH conference.
Ignorance about what works is a barrier to production of high-performance buildings. "We are in a totally experimental stage," said architect Antony Wood, executive director of Chicago-based CTBUH and visiting associate professor at the Illinois Institute of Technology, where the council is located.
"The whole building industry needs to acknowledge it needs to reeducate itself."
To help fill the knowledge gap about green design, CTBUH is planning a tall-building sustainability guideline. The council also plans to mobilize architects, engineers, financial institutions and other groups, including perhaps the World Green Building Council, to push for lease requirements for energy audits.
"The only way we can get to sustainability is to get [post-occupancy] information on energy use to the design community," said structural engineer David Scott, CTBUH chairman and a principal of Arup New York, New York City. "The incentive for [developers to do this] must come from tenants."
A general barrier to sustainability is inertia, said Sadhu Johnston, chief environmental officer for Chicago, considered a model green city in the U.S. "People are slow to change," he said.
Peter Wynne Rees, London's city planning officer, said the main obstacle is the requirement for conservation. "Using less is not popular," he said.
Johnston thinks greening can be sold because it "makes sense economically and politically." Even green retrofits for buildings, which gobble about 40% of the world's energy use, make dollar sense.
"We will not achieve 25% reduction in carbon emissions by 2020 and 80% by 2050 without retrofits," said Johnston. Retrofits save Chicago's Merchandise Mart, the world's largest private building, 20% in annual energy costs and Chicago's Sears Tower $2.5 million, he said.
There is little disagreement among experts that tall urban buildings have the potential to be the most sustainable building type because of high occupancy densities relative to small footprints. But most development is selling excessive luxury, not conservation. This is especially true in super-heated markets in the United Arab Emirates (see p. 13-14). Anticipating oil reserves drying up, Dubai and Abu Dhabi are become resort meccas.
The irony of holding a conference on sustainability in unsustainable Dubai, where water is desalinated, road congestion and pollution is rampant and all buildings are super-cooled, was not lost on attendees. Many point to the tallest structure in the world, currently more than 600 meters, as an example of energy gluttony. The mostly residential Burj Dubai, likely to exceed 800 meters, does not even have a shaded curtain wall.
Wood says CTBUH selected Dubai not only because it is the "epicenter" of tall-building development but to "put a message out to the local populace" about sustainability. "Everyone laughed at His Excellency Sheikh Mohammed Bin Rashid Al Maktoum when he said he was going to build a city out of dust in 15 years," said Wood. "Now he says the city will be realigned along sustainable principles. Should everybody laugh again?"
Wood was referring to the sheikh's Oct. 24 resolution implementing green building standards. LEED Emirates, a modification of the U.S. Green Building Council's Leadership in Energy and Environmental Design rating system, is expected to be ratified by September.
In response to comments that green requirements are coming too late to Dubai, Hussain Nasser Lootah, acting director general of the municipality, said, "Dubai buildings will be converted to green buildings."
In another step toward sustainability in the U.A.E., the Masdar Initiative, developer of a planned $22-billion sustainable city in Abu Dhabi, announced the designer for its "positive-energy" headquarters. The concept by Adrian Smith + Gordon Gill Architecture, Chicago, includes wind turbines and solar collectors.
In the area of high-performance high-rises in seismic zones, CTBUH's seismic committee last week released a draft document for public comment on performance-based seismic design of tall buildings, available on http://www.ctbuh.org More .than 50 seismic engineers from around the globe came to a consensus that "existing seismic codes are being used inappropriately for tall buildings and should not be used," said Scott.
"This is not to say we have a major problem with all our tall buildings," he said. "But the assumption that if you follow the codes, the building will be fine, is false."
The seismic guideline is "definitely needed" to standardize best practices in seismic zones and start to unify building codes globally, said Rene Lagos, of the Santiago, Chile-based firm that bears his name. Lagos is structural engineer for the future tallest building in Latin America, the 300-meter Torre Costanera, in seismic Santiago. The tower, now at about the fifth floor, would take the record from Mexico City's 230-m Torre Mayor.
According to CTBUH, there are big changes coming in height rankings. In its projected view of 2020, the Burj Dubai would be ranked third, dwarfed by the proposed 1,050-m Al Burj in Dubai and the proposed 1,001-m Burj Mubarak al-Kabir in Subiya, Kuwait. The current tallest completed building, Taipei 101, would fall to 14th, and the second tallest, the 452-m twin Petronas Towers in Kuala Lumpur, Malaysia, would sink to 20th.
Among its many rankings, the council tracks tall buildings topped out but incomplete. The five tallest are the 492-m Shanghai World Financial Center, New York City's 366-m Bank of America Tower, Dubai's 360-m Almas Tower, Pyongyang, North Korea's 330-m Ryugyong Hotel and Beijing's 330-m China World Trade Center Tower III.
With hundreds of other tall buildings planned or under way, it was clear to conference attendees that the Sept. 11, 2001, destruction of the World Trade Center's 110-story twin towers did not put a damper on high-rise development. On the contrary, "over the last five years, there has been an unprecedented worldwide construction boom in tall buildings and urban development," said Scott.