New York’s Freedom Tower
Raises Green Building
to New Heights

By Stephanie Aurora Lewis, LEED AP

Just as the emblematic torch of the new Freedom Tower will soar 1,776 feet in the air above New York City, the Freedom Tower’s “green” building features rise above present-day industry standards. Headquartered in an office in the area of 7 World Trade Center (WTC), a
committed and talented team works on innovative technologies,
materials and construction methods that characterize “green” inspiration at the Freedom Tower. Led by Larry Silverstein, President and CEO of Silverstein Properties, Inc., the other leading members of the team are the Architect David M. Childs, FAIA, Design Partner in Charge at Skidmore, Owings & Merrill, LLP, and the General Contractor
Tishman Construction Corp. An office building with an exceptionally high level of environmental sustainability, on such a large scale, reflects the remarkable commitment from Silverstein and from the many talented and experienced team members. Governor George Pataki congratulates the close-knit design crew for a tremendous building that raises industry standards for a “greener” New York City of the future.

In sum, Silverstein’s “green” efforts are measured by the United States Green Building Commission (USGBC) and directed through Leadership in Energy and Environmental Design (LEED). These organizations were established in response to the fact that buildings produce approximately thirty percent of this country’s greenhouse emissions that in turn contribute to detrimental climate change. In an attempt to quantify and reward environmentally friendly building practices, the LEED program developed standard definitions and checklists that certify levels of “green” design. The levels start at Certified, and go up to Silver, Gold and Platinum. Platinum is rarely achieved and is sometimes impossible to attain based on factors beyond the control of the builder. The WTC tower achieved Gold status in the LEED Core and Shell category. Among various and specific categories, Core and Shell relate to building elements such as the structure, envelope and building level systems.

Larry Silverstein, President and CEO, made his first deal in the early 1950’s when he leased a loft in Lower Manhattan for fifty cents per square foot. Now, the billionaire, who has developed, owns and manages more than twenty million square feet of office, residential and retail space, is leasing office space in the WTC site for approximately fifty to sixty dollars a square foot – forty percent higher than surrounding generic Lower Manhattan office buildings. The road to success, however, at the World Trade Center has been very challenging. When Silverstein completed the largest real estate transaction in New York City history by acquiring the ten million square feet at the WTC, he lost it in a terror attack only six weeks later. Taking a misfortune and turning it into a national strength is an incredible feat for which Silverstein believes will be part of his legacy.

The Freedom Tower follows in the “green” footsteps of the WTC tower. Since the structure won the Award from the Municipal Art Society for “exemplifying the highest standards of architectural design,” one can only imagine how spectacular the new Freedom Tower will be. David M. Childs, FAIA of SOM, LLP, designed both buildings to exhibit very high “green” standards. The Freedom Tower will use much of the same innovative materials and technologies, but will go a step beyond its predecessor. Not only will the building be an example of “green” architecture, it will also be beautiful. SOM has received 850 design awards, and is known for beautiful design. The base of the Freedom Tower is made from glass panels that emit prisms of colored light. These prisms dance light into the public square and seem to move along in space as one passes by in reflection.

With his gracious demeanor, at the LEED Gold certification award assembly for 7 WTC, Silverstein explained his commitment to the environment this way: “As part of our response to 9/11, we at Silverstein Properties pledged to conserve New York’s most precious resources, including water and energy. We pledged to create a healthy, enjoyable and productive environment for the people who work here. And we pledged to safeguard the health of the people who live, work, visit and go to school in Lower Manhattan… We have raised the bar for green construction in New York City.” Governor Pataki recognized the new WTC building designs and respective Sustainability Standards as a model of a business district that has high environmental standards. He pointed out that the success of 7 WTC proves economic development and environmental responsibility can work hand-in-hand. He went on to recognize that a twenty-first century business district requires environmental consciousness and commitment by both the private and public sectors.

A required commitment to build “green” typically costs more money once it surpasses the Certified level. Most often, however, added costs are reclaimed through energy savings. Yet, on some occasions, the “green” alternative may cost less. For example, Tishman Construction Corp., on excavating bedrock for the new foundation of the Freedom Tower, saved an enormous amount of time and fuel, noise and dust by blasting through some of the bedrock rather than removing it mechanically. Mel Ruffini, Senior Vice President at Tishman, said “It is not only a schedule savings, but a better environmental approach.” Tishman’s careful research regarding bedrock excavation enlightens
the fact that building “green” is a process, that begins at the design and construction phases and continues through to the day-to- day operations. Tishman Construction Corp., has been intimately involved with the “green” building movement in New York City since the eighties. They have constructed several “green” buildings and hold a legacy for their great contribution to the industry by way of sustainable design. Since 1959, Tishman has had a Research and Development department that works on such environmental issues and generates creative solutions.

The standard for clean air through the exclusive use of environmental-saving construction vehicles earned Silverstein Properties, LLP, a 2004 EPA Environmental Quality Award. Clean air is better preserved due to ultra-low sulfur fuels that reduce emissions of nitrogen oxides and particulate matter from heavy-duty vehicles typically powered by diesel fuel. In conjunction with the alternative fuel, Tishman implemented particulate filters to clean emissions rather than to negatively exhaust them into the environment.

Some of the elements that define the LEED Gold Level at 7 WTC are as follows: more open space for the public, more natural light, glass that conserves energy by blocking heat and uninhibiting light, excellent indoor air quality through the use of a high-efficiency filtration system, steam to electricity turbine
generators, variable speed fans, harvesting rainwater for reuse in the cooling system and for irrigating the park, waste reduction through diversion of more than seventy-five percent of construction waste and use of recycled content materials.
Glass technologies are constantly evolving. In the past,
energy-saving glass meant that it was darkened. At 7 WTC,
the high-tech glass blocks ultraviolet rays that cause heat, while maintaining clear glass, that allows full sunlight to illuminate the interiors. A steam to electricity turbine conserves energy
by using steam that in turn generates an electric current.

The variable speed fan relates to the indoor/outdoor air ventilation fan that is operated depending on mechanical need rather than at a single constant speed. The fan can operate
at full speed or it can reduce down to a zero energy pull. Since not all water used in a building is potable, gray water can be harvested from rainfall and recycled through various point-of-use water supplies throughout the building. There are many different techniques used to do this from a simple pickle barrel in a home owner’s backyard to a multi-faceted system, such as that implemented at 7 WTC and the Freedom Tower, that balances the supply v. demand water source between rainfalls. In addition to conservation, and improving
employee health and work satisfaction, there are many tax breaks and refund benefits for utilizing these systems and solutions. Further, labor costs for recycling building materials may be reclaimed.
At the Freedom Tower, sustainability standards have improved
even more in comparison to the award winning WTC. Cogeneration and fuel cells, on-site and off-site renewable energy sources, such as wind energy, are special features in the Freedom Tower. Cogeneration is the result of a heat
engine or a power station that generates electricity and heat at the same time. This is the most efficient use of electricity
on an energy basis standard. Where heat energy is lost through electricity generation, the energy produced by heat is actually reclaimed through the HVAC system. Similar to a battery, a fuel cell makes electricity more efficiently and keeps the environment cleaner. Wind power can be purchased through credits then given to an electric power company in the grid on which the building is located. Even though renewable energy may not always be available on-site, this credit system allows a building owner to support and to demand that energy be purchased from renewable sources. Wind farms are located throughout the country.
In the Freedom Tower, electricity costs are expected to be thirty-five percent lower than surrounding generic Manhattan
office buildings. Fifty percent of the energy comes from renewable sources such as the wind farms mentioned earlier. Full height low-iron glass allows tenants to install daylight dimming controls. High efficiency cooling and heating systems surpass local energy codes with high efficiency filters to improve indoor air quality. Low-VOC paints are the standard throughout the building. VOC’s, or volatile organic compounds, are carcinogens and unhealthy. High efficiency plumbing systems save thirty percent of water consumption, such as low-flow toilets and devices to limit water use for hand washing. Rainwater collection systems supply water for the irrigation system as well as for the cooling tower. Carbon dioxide sensors are installed throughout the building. There was no use of ozone-depleting HCFC refrigerants in the mechanical systems. The maximum use of post-consumer recycled content was used for building materials. Fifty percent
of wood on the project comes from certified sustainable harvested forests. Under the US Forest Stewardship Council, sustainable forests provide new growth to replace trees removed
for construction or other purposes. Ninety percent of the interior workspaces have outdoor views throughout the building. Many research studies show that employees experience
better holistic health when they have exterior views and natural daylight in their workspaces.
Larry Silverstein stated that, “Given the speed at which new technologies are emerging and given the relationships we have built with pioneering organizations such as the National Resources Defense Council and Clean Air Communities,
we expect that we will continue to raise the bar from our environmental standpoint as we move forward.” Mickey
Kupperman, Senior Consultant at Silverstein Properties, states that there is a great spirit among the working members of the team to rebuild the World Trade Center and the Freedom Tower. He believes their stories will be retold to generations in the future about what it was like to put things back
together. The Freedom Tower is summed up so well by Childs as he states, “This is a city that believes in looking forward.”