Thirteen years ago today the twin towers were destroyed by terrorists, but from the ashes of that terrible day new green World Trade Center buildings have taken their place. Seven World Trade Center (7 WTC) was completed in 2006 and the much larger One World Trade Center (1 WTC) also known as “Freedom Tower” was completed in 2013. These building are models of sustainable design.
Seven World Trade Center
7 WTC is a pioneer in terms of environmental responsibility, energy efficiency, and quality of life. The building has earned the U.S. Green Building Council’s (USGBC) gold status under its Leadership in Energy and Environmental Design (LEED)-rating system. This is the first green commercial office building in New York City to have such certification. It is also part of part of the USGBC Pilot Program for Leadership in Energy and Environmental Design – Core and Shell Development (LEED-CS).
7 WTC green leadership has been recognized by the Environmental Protection Agency (EPA), the Municipal Arts Society of New York, and the American Institute of Architects New York Chapter.
Sustainability concerns were a part of the 7 WTC from its inception, this also included the construction process. With the aim of reducing smog, acid rain and water pollution construction incorporated the Diesel Emissions Reduction Project. This reduced emissions from heavy construction equipment by as much as 90 percent.
Green design features of 7 WTC:
7 WTC offers tenants the ability to provide direct daylight and outside views for more than 90 percent of their regularly occupied space.
Full-height low-iron glass allows tenants to reduce energy costs by installing daylight dimming controls.
One hundred percent of 7 WTC’s core-and-shell electricity needs comes from renewable energy.
In a typical business year, electricity costs at 7 WTC will be approximately 35 percent lower than in a generic Manhattan office building, due in part to a power purchase agreement with New York Power Authority.
7 WTC features environmental innovations that exceed those of traditional office buildings, such as:
- High-efficiency cooling/heating systems (beyond current code requirements), with high-efficiency filters in all A/C units to improve indoor air quality;
- Use of paints that are low in volatile organic compounds;
- High-efficiency plumbing systems that will reduce water consumption throughout the building by at least 30 percent;
- Collection of rainwater from the roof for irrigation of the nearby park and for the cooling tower;
- Carbon-dioxide sensors throughout the building;
- No use of ozone-depleting HCFC refrigerants;
- Building materials that will include post-consumer recycled content (at least 50 percent of the building’s wood is certified as sustainably harvested).
One World Trade Center
Seven World Trade Center is dwarfed by One World Trade Center which has also earned Gold status. In addition to a host of robust security measures, 1 WTC is the tallest building in the US and one of the tallest buildings in the world. It is precisely 1,776 feet high, in honor of the year of American independence.
The three billion dollar 1 WTC project is the most environmentally sustainable building of its size in the world. It incorporates new environmental standards and gets 70 percent of its power from green sources.
Green elements of the building and construction:
Fuel cells. 12 United Technologies Corporation (UTC) Power PureCell Model 400 fuel cell stacks have been installed in the building. These fuel cells will provide 4.8 million watts per hour of clean energy when operational, and the combined systems rank as one of the largest fuel cell installations in the world, according to UTC.
Waste steam recycling. Waste heat output from this fuel cell system is recycled and used for hot water and heating in the podium of the building’s structure and the entrances, amounting to 70,000 BTUs of high-grade heat and 500,000 BTUs of low-grade heat. Alternatively, with the addition of an absorption chiller, the system is capable of using the waste heat to produce about 50 tons of cooling for the building, eliminating some need to draw power off the grid for air conditioning.
World-class mass transit. Workers commuting to One World Trade Center have unprecedented access to mass transit service from the new complex. New climate-controlled corridors will connect the Freedom Tower to The World Trade Center Transportation Hub and the new PATH terminal, 11 NYC Transit subway lines and the new Fulton Street Transit Center, the World Financial Center and ferry terminal, underground parking and retail and dining facilities.
Exceeding code. Overall, the building’s energy performance exceeds code requirements by 20 percent.
Recycled rainwater. Rainwater is claimed and re-used for building cooling purposes as well as fire protection, supplemental cooling and irrigation for the complex’s extensive landscaping needs. The rain water – 60 inches annually in New York, making it one of the rainiest of American cities – is stored in new high-efficiency evaporative cooling towers located on-site.
Functional memorial. The large, square reflecting pools which mark the “footprints” of the original World Trade Center twin towers feature 360-degree waterfalls and serve as rain collection systems themselves. The names of those who died on September 11 are inscribed on plaques around the “footprint” waterfalls. The names appear dark during the day and glow with internal light at night.
Central chiller. Air conditioning is supplied, in part, by a highly efficient 12,500-ton Central Chiller Plant (CCP) that uses water from the Hudson River to cool the WTC Transportation Hub, National September 11 Memorial and Museum, retail space and some non-commercial areas. The plant circulates 30,000 gallons of river water every minute.
Landscaping. The new main plaza of the World Trade Center complex features more than 400 trees, all of which were harvested within a 500-mile radius of the city to avoid excessive transportation and limit the amount of greenhouse gas emissions. The trees’ roots help keep temperatures regulated within the museum that lies below.
Waste material recycling. Construction at the building site has been recycled about 80 percent of waste materials generated at the site, exceeding its own target by about 20 percent.
Recycled building materials. Everything from the facility’s gypsum boards to ceiling tiles contains a minimum of 75 percent post-industrial recycled content. This reduces the environmental footprint, not only on-site, but reduces the stress on the natural resources and energy needed to produce them.
Taking a pass on cement. The construction of One World Trade Center used so-called “Green Concrete,” – what some believe to be more environmentally responsible than traditional cement – which will save about 12 million pounds of carbon dioxide emissions, 8 million kWh of energy and 30,000 gallons of fresh water. (It does, however, contain coal fly ash, which comes with some environmental challenges of its own.)
Clean diesel. During construction, contractors were required to use only ultra-low sulfur diesel fuels, or “clean diesel” to reduces nitrogen oxide and particulate emissions in and around the construction area. In addition, all construction vehicles are equipped with extra particulate filters to further reduce their environmental impact on air quality.
No VOCs. Any use of materials that contain VOCs – volatile organic compounds, or chemicals that leach from building materials in gaseous form and cause health problems – has been banned from the entire reconstructed World Trade Center complex.
Preventing a “sick” green building. Indoor air quality is continually monitored with a high-tech system. Carbon dioxide monitors control ventilation and make the building healthier and improve indoor air quality. If the monitors sense more carbon dioxide than is healthy, they send a signal to the air handler software, telling it more fresh air is needed in that space. The system then automatically increases the fresh air mix in the area. The buildings contain over 3,000 points of monitoring, according to Eduardo Del Valle, Director of Design Management at One World Trade Center.
Daylighting. The buildings uses a green feature called “daylighting,” which means that on bright, sunny days when a large amount of natural daylight is coming into the windows, dimmers automatically lower the interior lights to reduce energy consumption. Every space within 15 feet of the building’s facade is equipped with dimming devices. In addition, the buildings’ windows are constructed of ultra-clear glass, which will allow a maximum amount of light in while blocking excess heat from entering.
Green port-a-potties. During construction, workers used composting toilets in place of the familiar, chemical portable toilets. In composting toilets waste mixes with other decaying biological products and creates nutrient-rich soil. Human waste was fully processed, more than 90 percent of it is re-used, eliminating the need to constantly empty and re-plenish the water in traditional portable toilets.
Low-water bathrooms. The building includes high-efficiency plumbing systems designed to save thirty percent on water consumption over a typical building of its size. To achieve this, builders installed low-flow toilets and devices to limit water use for hand washing.
Save the ozone. Builders barred the use of ozone-depleting HCFC refrigerants in the building’s mechanical systems.
Sustainable wood. Fully fifty percent of wood used in the buildings of the new World Trade Center was sourced from Forest Stewardship Council-certified (FSC) sustainable harvested forests. FSC certification mandates that the wood used in a building project came from responsible sources and not from endangered trees or forests.
1 WTC and 7 WTC do more than conserve valuable resources. These buildings have set the bar for green design which other buildings are sure to follow.
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