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Bank of America Towers Over Manhattan

Credits: ©2007 Wikipedia

The design of the Bank of America Tower in New York City is an environmentally friendly skyscraper, using green architecture technologies such as floor-to-ceiling insulating glass to contain heat and maximize natural light, and an automatic daylight dimming system. The tower features a graywater system, which captures rainwater and reuses it. The green building is made largely of recycled and recyclable materials such as steel and drywall, and low-VOC products. Air entering the building will be filtered, as is common, but the exhausted air will be cleaned as well. The building includes a five-megawatt cogeneration plant, ice storage plant, , green roof areas and waterless urinals.

 

Bank of America Tower Night Colors

At 42nd Street and Sixth Avenue, opposite Bryant Park, near Times Square in Manhattan, the bank of America Tower comprises the largest development site (two acres) in Midtown Manhattan. ©2009 dBox for Cook+Fox Architects

The Bank of America tower is constructed using a concrete manufactured with slag, a byproduct of blast furnaces. The mixture used in the tower concrete is 55% cement and 45% slag. The use of slag cement reduces damage to the environment by decreasing the amount of cement needed for the building, which in turn lowers the amount of carbon dioxide greenhouse gas produced through normal cement manufacturing. (One ton of cement produced emits about one ton of carbon dioxide into the atmosphere.)

Control of the temperature of Bank of America's tower, and the production of some of its energy, will be done in an environmentally-friendly manner. Insulating glass will reduce thermal loss somewhat, which will lower energy consumption and increase transparency. Carbon dioxide sensors will signal increased fresh air ventilation, when elevated levels of carbon dioxide are detected in the building.

Conditioned air for the occupants is provided by multiple air column units located in the tenant space that deliver 62 degree air into a raised access floor plenum. This underfloor air system provides users with the ability to control their own space temperature as well as improving the ventilation effectiveness. When building churn occurs, workstation moves can be performed easier with lower cost and less product waste.

The cooling system will produce and store ice during off-peak hours, and then use ice phase transition to help cool the building during peak load, similar to the ice batteries in the 1995 Hotel New Otani in Tokyo, Japan. Ice batteries have been used since absorption chillers first made ice commercially 150 years ago, before the electric light bulb was invented.

Water conservation features in the tower include waterless urinals, which are estimated to save 8 million gallons of water per year and reduce CO2 emissions by 144,000 pounds per year (as calculated with the Pacific Institute water-to-air model).

The tower has a 4.6-megawatt cogeneration plant, which will provide part of the base-load energy requirements. Onsite power generation reduces the significant electrical transmission losses that are typical of central power production plants.

The tower's architectural spire is 255.5 ft (77.9 m) tall. The building is 58 stories high and has 2,100,000 square feet (195,096 m2) of office space. Its final height was reached upon the placement of its spire in December 2007. The building has three escalators and a total of 53 elevators – 52 to serve the offices and one leading to the transit mezzanine below ground.

The Cogeneration Plant
Joann Gonchar, AIA
Though already common in industrial applications, combined heat and power [CHP] technology is rarely used in buildings in the U.S., even though it can provide a more efficient and lower greenhouse-gas-emitting alternative to traditional grid-supplied power. But one project that is a CHP pioneer is under construction in Midtown Manhattan and is headed for completion later this year.

Designed by Cook+Fox Architects, and jointly owned by the its primary tenant, the Bank of America, and the developer, the Durst Organization, the 55-story Bank of America Tower (formerly known as One Bryant Park ) will have a 4.6-megawatt CHP system. The designers and owners say that the building will be the first high-rise commercial office tower in the country to use this technology at such a scale. The CHP plant will satisfy about one third of Bank of America’s peak power demands and will provide for almost 70 percent of its energy needs on an annual basis.

Also known as cogeneration, CHP involves simultaneous production of electricity and useful thermal energy (typically steam) from a single fuel source (often natural gas). At Bank of America, the heat produced by its natural-gas-fired turbines will be used to make steam, which in turn will be used to heat the building and the domestic water supply, and to operate an absorption chiller for cooling.

Relying on CHP for much of its energy needs should significantly reduce the carbon emissions of the tower compared to a conventional office building dependent solely on the grid. Part of these savings are due to its distributed energy strategy. The term “distributed energy” refers to a generation source that is an alternative or enhancement of traditional grid-supplied power, located in close proximity to the building it supplies. Such systems can be more efficient than centralized generation since electricity carried over the grid loses 7 to 8 percent of its power in transmission, according to some estimates. However, retaining this electricity is a relatively minor contributor to the efficiency of CHP, since a much larger portion (about two thirds) of the energy generated at traditional power plants escapes through smokestacks. “By preventing transmission loss, CHP does save something on an overall Btu basis,” says Don Winston, Durst director of technical services. “But it is the heat recovery that really makes the system work,” he says.

About 86 gigawatts of CHP capacity are currently operating in the U.S.; however, the vast majority of these facilities are located at industrial sites rather than in individual buildings, according to Richard Sweetser, president of Exergy Partners, a consulting firm based in Herndon, Virginia. Sources say a number of factors make cogeneration a good choice for industrial applications, including a relatively flat demand for energy over the course of the day and through the various seasons. But in buildings, this demand is generally more variable, creating challenges for making the most of a cogeneration system’s thermal output. “If you are sending steam to the roof, CHP doesn’t make [economic] sense,” says Vinnie Galatro, director of technical services for the Fulcrum Group, commissioning agent for the Bank of America Tower project.

In order to avoid wasting valuable thermal energy, Bank of America Tower includes a thermal storage system that will produce ice at night from excess steam. Then, during peak daytime hours, the ice will be used for cooling, resulting in “a nice and even load profile 24 hours a day,” says Galatro. Other challenges with which the Bank of America team had to contend included routing natural gas lines through a densely occupied structure, and the isolation of the CHP equipment for noise and vibration. There were also permitting and regulatory hurdles, though New York City officials are working to reduce such barriers to achieve a goal of 800 megawatts of installed clean distributed energy by 2030.

But impediments aside, CHP proponents say that the technology is an economically and environmentally viable alternative to the construction of additional conventional centralized generation capacity. According to Scott Frank, partner at Jaros Baum & Bolles, the project’s mechanical engineer, “generating electricity on-site and using the waste heat just makes sense.” Joann Gonchar, AIA

 

Interview with Lead Architect Serge Appel

by Jill Danyelle, 10/02/08, Inhabitat

I had the opportunity to talk to lead architect Serge Appel about the finer points the tower’s design and construction – read on for our exclusive interview >

One Bryant Park is the first LEED platinum “skyscraper”; what is your favorite LEED aspect of the project? Aside from LEED, what was the most interesting or exciting part of the project for you?
For me, the best part of this project isn’t a single element or technology but rather the chance to work with an incredible team of dedicated professionals all driven by the same goal. Having the backing of the Bank of America and the Durst Organization has made a tremendous difference in setting the bar high in terms of sustainable design. On top of that, each consultant on the team is top notch and fully engaged with the project.

What was your least favorite or the most difficult thing about the project?
Certainly the most difficult part of this project has been the intense and detailed coordination required for such a large and complex building. The vast majority of that has far less to do with the green elements than with the requirements of a major banking institution being built in the middle of midtown Manhattan post 9/11.

Architecture has delayed gratification in terms of realization when compared with other design fields. One Bryant Park has been under construction for four years now. To what extent are you involved in the process? What is it like to work on a project that takes six years from first sketch to completed structure?
I’m still involved daily in almost all aspects of the project, from the spire detailing to quality control on the installation of the curtain wall. Even after several years, there’s always something exciting and new right around the corner – not to mention that One Bryant Park is not your ordinary office building. Even still, staying personally motivated and keeping a team of people working over many years requires a strong sense of ownership and responsibility, as well as a fair amount of patience. Fortunately, projects this large are always broken down into smaller pieces, each with its own bit of gratification.

Can you explain how the big ice cubes in the basement will work?
They’re not exactly giant ice cubes, but the thermal storage system basically works like a “battery” for cooling. In the basement, there are 44 10-foot high, cylindrical tanks with water and a cooling coil inside. At night, when electrical production from the co-generation plant exceeds the building’s needs, we use that excess to run the chilling equipment to freeze the water in the tanks. During the day, the ice melts and provides cooling to the building. This shifts some of the electrical load from daytime to nighttime, which reduces the impact on an already stressed NYC electric grid.

How about those waterless urinals?
Waterless urinals are pretty straightforward; from the point of view of the user, there is no real difference. We have them in our own office, which we moved into last year and is also LEED Platinum – the first in New York. Instead of flushing, the urinals have a special drain fitted with a cartridge full of a liquid less dense than urine, which “floats” on top and seals out odors. Like all urinals, they have to be regularly maintained and cleaned and the cartridge has to be changed on occasion.

People are still wondering if “green” is just a trend. Where it often costs more to produce green products, in terms of buildings, the energy savings seem to actually make building green more cost-effective in the long run. Were there any environmental aspects of the design that needed to be compromised due to cost?
Building green is not a trend, at least not in our minds. The idea of building green really is about building smarter, higher performing buildings which are considerate of the people who live or work in them. Like any other aspect of the building, the benefits need to be weighed against the costs. There were several items which just couldn’t be justified today. When we started the project, we were sure that there would be building-integrated photovoltaics, but the more we looked at the amount of electricity generated, the less it made sense. We also looked seriously at including a wind turbine – in fact, the building originally had two spires, one architectural and one for the wind turbine. We even set up an anemometer on top of the adjacent 4 Times Square and took a full year of wind measurements. What we discovered is that while there is sufficient “quantity” of wind, it isn’t consistent enough to make the power generated worthwhile, at least not at the current state of the technology.

Maybe this is a question for Jordan Barowitz over at the Durst Organization, the developers of the project, but do you know to what extent being LEED platinum has been a selling point for the building, which I believe is almost completely leased?
The building is almost fully leased, and from what we have heard being green has made a significant difference. We are designing one of the tenant floors at the moment for fashion designer Elie Tahari LTD, and the green elements of this building were very important to them.


Resources

Cool Idea: Using Ice to Chill Buildings in NYC

Bank of America Tower Podcast