Maximum Efficiency

Battery Park City’s 50 West Looks to Keep Sustainability Simple

By Tom Nicholson

Excavation is under way at 50 West Street in Battery Park City in preparation for construction of a 65-floor residential tower that is on target for LEED gold certification when completed in 2011.

Designed by Helmut Jahn of Chicago- based Murphy Jahn Architects, the $600-million, 580-million-sq–ft, mixed-use tower’s 280 residential and 155 hotel units will be housed in an envelope of high-performance glass that maximizes use of natural light while filtering UV rays. The building is topped by a green roof.

The project team behind Battery Park City's 50 West is looking to achieve LEED Gold certification without using such "complex" sustainable technologies such as natural gas microturbines, water treatment facilities or rooftop solar voltaic panels.

Inside the slim, transparent tower, green features include high-performance appliances, HVAC and plumbing systems; automated blinds; and energy-control systems.
A rainwater catchment system on the roof and in the ground-level plaza will provide irrigation water for landscaping, says Dermot Johnson, director of project management for New York-based developer Time Equities Inc. “We made a conscious choice to go as green as possible,” Johnson adds.

Amid projects in Battery Park City that involve complex sustainability technology such as natural gas micro turbines, water treatment facilities and roof-top solar voltaic panels, the 50 West project is an example of how basic green features coupled with sustainable building practices can attain LEED gold certification, says Tom Chambers, principal architect at Murphy Jahn Architects.

Design “took a year of hard work,” says Johnson, who describes the project‘s design process as a collaborative process between architect, owner and the city. The site’s tight quarters and small footprint were key considerations throughout.

To address staging, “we’ve had to work closely with the city Department of Transportation to divert pedestrian traffic to use a full street lane,” Johnson says.

Battery Park City Authority assisted the team in meeting the design, materials, performance and building-practice requirements of its stringent environmental guidelines, Johnson adds.

“A lot of the green points on this project have to do with construction,” says Chambers, pointing to LEED points earned for documented reductions in construction waste and energy use and for recycling demolition waste. “It’s not as if this building has wind turbines or solar panels. It’s just designed to be efficient. You don’t need to go over the top to get LEED certification.”

LEED points were also garnered for use of interior finishes, caulks and paints that are free of health-threatening volatile organic compounds, Chambers adds.

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Demolition of three existing buildings is completed at the site, located between West and Washington streets at J.P. Ward Street just north of the Brooklyn-Battery Tunnel entrance, and caisson installation has begun.

“We’ve made the first 5-ft (excavation) cut and have started installation of the perimeter caissons,” says project manager Bill Grutta of New York-based HRH Construction LLC.

A soldier-piling and wood-lagging foundation system on the project allows installation of caissons without the need for initial deep excavation of the site. The lagging approach is speedier than the bathtub slurry wall foundations common in the 92-acre district where a high water table complicates foundation work, Grutta adds.

“When we get down to about 7 ft we’ll hit water and then we’ll pump around the clock for the next five or six months,” he says.

The 9,000-sq-ft floor plate of the building requires a single concrete pour, in contrast to buildings with larger floor plates where two pours per floor are typical, Grutta says. “We can’t break it down into two pours, which will mean long days when we start pouring concrete,” he says. More than 400 workers will be onsite during that time, he adds.

The project also includes construction of a pedestrian bridge to span West Street, linking the southern part of Battery Park City to Wall Street, Grutta says.

As a solution to the small footprint at the site, the cantilevered structure of the building provides wider upper floors and increases area space of the ground-level plaza. “A lot of the design considerations had to do with site utilization,” Chambers says.

Johnson says the cantilever design concept was chosen through a request-for-proposal competition and was a key factor in selection of HRH Construction.

“Having columns on an angle (to accommodate the cantilever curve) was a complex project and we needed a contractor who was qualified,” he says. “We also wanted a contractor with broad mechanical, electrical and plumbing experience since that is major part of building efficiency.”