An amazing example of cutting-edge green building technology is a recent addition to New York City’s famous skyline: The Bank of America Tower, near Times Square. Completed in 2009, it is New York’s second tallest skyscraper, shorter only than the well-known Empire State Building.
With this project, the development team sought to demonstrate that ecological principles and economic principles can be made compatible. Of possible green features that involved added cost, only those that would pay for themselves (in reduced operating costs) within five years were included. The result is an outstanding landmark based on sustainable principles.
The Bank of America Tower successfully exploits every aspect of green building, including:
- Site Selection
For a new building, the best choice for a site is in an existing city, near public transportation and amenities, on land that had been previously developed. The location near Times Square in New York City scores very high in this regard.
- Building Form
This tall and very visible building makes a good example of how a passive feature such as the form of a building can create a variety of benefits. The most striking feature of the building is the sloping exterior walls that chamfer the corners. This could be mistaken for a stylistic achievement, but the hidden story is more interesting and helpful. Facing the sky and sun, the sloped walls admit more sunlight into the interior spaces, and are also more effective in capturing rainwater for collection and use. Also, the sloping aspect of the building allows for more light and air in the neighborhood surrounding it.
The shape of the floor plan now allows diagonal views from the interior, benefiting the indoor environment by providing vistas that are unusual in a city of square buildings facing each other across narrow streets on square blocks. Floor-to-ceiling windows provide outdoor views for 90% of the workers inside, and daylight penetrates to the center of the floors.
- Energy Conservation
This building uses an onsite natural gas-fueled power plant to provide 70% of annual electrical power needs, and about 30% of peak demand (the highest electricity usage experienced at any one time). On-site power generation eliminates electrical transmission losses that are significant in the distribution grid which relies upon centralized generating plants. In a process called cogeneration, waste heat from the power plant is used to make steam which powers chilling machines to cool the building, as well as providing hot water for heating. The plant also produces all of the building’s hot water without outside energy.
- Peak Demand Shaving
At night, the on-site power plant provides the energy to make large amounts of ice, which is stored in tanks and used to help cool the building during the day. Therefore the power plant reduces the buildings peak (daytime) power demand on the utility grid in two ways.
- Water Conservation
The use of waterless urinals in this very large building saves 8 million gallons of water per year alone. Rainwater is collected on roofs and used for cooling purposes and for flushing toilets. Overall, about 100 million gallons of water per year are saved, and virtually no storm water is allowed to drain to the city’s sewer system.
- Materials and Resources
40% of the materials used in construction were regionally sourced (from within 500 miles of the project), reducing energy use for transportation, and supporting regional economies.
This building used fly-ash, a recycled material, to save 45% of the cement that would have been used in concrete; reducing waste and eliminating a significant amount of pollution that is caused by the manufacture of cement. Recycled steel and other materials were also used.
83% of construction waste was recycled, and diverted from landfills.
- Environmental Quality
All of the fresh air used in the building is collected at roof level and treated by highly efficient filters before being distributed to indoor spaces. Unlike other buildings, Bank of America Tower filters the air again before it is exhausted to the outside – the result is that the air leaving the building is cleaner than the air that was drawn in. This is a benefit to the environmental quality of the neighborhood and the city.
Indoor environments are improved by an innovative air distribution system, adequate fresh and clean air, and extensive use of natural daylight. Fresh air ventilation is controlled by sensors that measure the amount of carbon dioxide (“stale air”) in interior spaces. Improved controllability of the air-conditioning system gives more efficient and healthy heating and cooling.