The new 7 WTC building will be New York's safest and "greenest" skyscraper

Tucked between the Woolworth Building and 3 World Financial Center is a short-lived sight: Two enormous cranes perched atop the new 7 World Trade Center, dipping and pivoting to pull the tower's steel skeleton skyward.

At 33 stories so far, the 7 WTC building is weekly changing Lower Manhattan's skyline with each floor added -- bringing it closer to its eventual rank (and temporary until the Freedom Tower is built) as Manhattan's fifth-tallest building south of the Empire State Building.

In fact, the tower-in-progress has several claims to fame just waiting to become official, such as being both the world's safest and "greenest" skyscraper. It also promises to capture a sense of openness and light for its tenants, all while the tones of its façade's glass skin transform with the weather and seasons.

Until Freedom Tower is completed, 7 WTC will be Manhattan's fifth-tallest building south of the Empire State Building

These innovations begin with WTC developer Larry Silverstein, whose lofty goal is to make the building a source of pride for New Yorkers. "He wanted to make sure what he did set standards in terms of environment and quality of work," says Silverstein Properties spokesperson Dara McQuillan.

To get there, Silverstein tapped renowned architect David Childs of Skidmore, Owings & Merrill to design 7 WTC, and skilled skyscraper contractor Tishman Construction to build it. And as testament to the team's efficient design and construction planning, which was not part of a public design competition like the main Trade Center site, work on the tower began in the summer of 2002.

The initial construction was complicated by having to restore the Con Edison electric substation that occupies its lower 10 floors. That substation was also a part of the original, 47-story 7 WTC, which opened in 1985 and collapsed at about 5 p.m. on September 11, 2001, from the fire caused by twin towers debris. However, with a battery of workers -- many of whom, remarkably, worked on the original building -- and their fast-track efforts, the substation was restored in May 2004 and is once again piping power to Battery Park City.

Now the focus is primarily on building 7 WTC's upper floors, which will reach an ultimate height of 750 feet, or 52 stories. The construction itself is part of the environmentally sound package that Silverstein has masterminded, highlighted by his use of ultra-low sulfur fuel in construction vehicles and other pollution-control measures that already have earned him a Quality Award from the Environmental Protection Agency.

It's fitting, then, that the building itself will raise the bar for "green" buildings, promising to earn Leadership in Energy and Environmental Design (or "LEED") certification. Its exterior walls will conserve energy, rainwater will help with cooling and irrigation, recycled-content building materials have already and will continue to reduce waste, and other conservation and air-quality measures will prove that high-rises actually can be responsible.

The office tower also will hold the title "safest office building in the country" according to McQuillan, who's quick to rattle off the long list of its "life-safety features," which far surpass current building codes. "Everything we've learned about safety we've applied to Seven World Trade," he says.

For example, elevators, utilities infrastructure, and exit stairs will be encased in the vertical core, made of two-foot-thick concrete walls that rise through the center of the building. It will have twice the required water-storage capacity for the sprinkler system, and pressurized ventilation to filter out air contaminants. On top of these enhancements, the tower is being built with redundancy in the steel frame, super fireproofing material, wider and better-lit stairs, more ground-level exits, emergency generators, and a redundant emergency command center.

In other words, Silverstein has created a building that will not be daunted by an emergency.

At a cost of $700 million to construct, 7 WTC will also make use of the latest in design and materials, starting with the iron-free, "ultra-clear" glass that is already showing up on parts of the tower's façade. From the street, the blueish tint will supposedly morph with the weather -- though it seems we won't be able to comprehend the extent of this detail until the façade is finished. From the inside, Childs designed lofty ceiling heights that are taller at the exterior wall than at the core, making the full-length windows feel bright and airy.

7 WTC will make use of the latest in design and materials like "ultra-clear" glass

With 1.7 million square feet to fill, Silverstein is already working on signing up tenants like law and accounting firms and investment companies. One tenant all ready to move in upon its late 2005 completion, however, will likely be its proudest: Silverstein Properties.