When asked to name the things that contribute most to global warming, the average person might mention gas-guzzling cars or perhaps factories that spew pollution into the air. But buildings, commercial and residential, account for 38 percent of carbon dioxide emissions in the United States. That’s more than any other sector of the economy, including transportation and industry.
Architects and engineers have developed ways to design buildings
that have a lower impact on the environment, and they’re now
setting their sights on bigger and bigger eco-friendly projects.
The U.S. Green Building
Council, a nonprofit consortium of industry groups, evaluates
buildings according to its Leadership
in Energy and Environmental Design (LEED)
rating system. Projects get scores in five areas: sustainable site
development, water savings, energy efficiency, materials selection
and indoor environmental quality. Once the points are tallied up,
buildings can win one of four awards: certified, silver, gold or
platinum, the highest rating. Many developers have made it a goal
to earn a LEED certification for their buildings. As concern over
global climate change increases, it’s clear that green buildings
will continue to sprout. —Corinna Wu
Bank of America Tower
- New York, N.Y.
- 2.1 million square feet
- 54 stories
- Completion expected in 2008
In New York City, skyscrapers are a dime a dozen. But the 945-foot-tall
Bank of America Tower, currently under construction in midtown Manhattan,
hopes to distinguish itself by being the first high-rise office
building to achieve a LEED platinum rating. When completed, the
sleek, crystalline tower will be the “world’s greenest
skyscraper,” according to The Durst Organization, which is
developing the high-rise with the bank.
is being constructed largely out of recycled or recyclable materials,
such as glass, steel and aluminum. Inside, several sophisticated
technologies will improve indoor air quality and save energy. The
building will have a displacement ventilation system that puts the
air conditioning vents on the floor instead of the ceiling. That
way, the air only has to be cooled to 65 degrees instead of 55 degrees
as in a conventional system. Rain and wastewater will be collected
and used for the cooling system and toilets, cutting the amount
of potable water consumed in half. A 5.1-megawatt cogeneration plant
on-site will generate electricity during the day and make ice at
night, as well as capture waste heat for warming the office space.
- Cambridge, Mass.
- 344,000 square feet
- 12 stories
- Completed November 2003
Cambridge, Mass., isn’t known for sunny skies, but a visitor to the Genzyme Center might be fooled. Located on the former site of a coal gasification plant near the MIT campus, the building serves as the biotechnology company’s corporate headquarters. No matter the time of day, sunlight pours in through the skylight atop the building’s central atrium thanks to large mirrors on the roof called heliostats. They follow the path of the sun and reflect it onto a set of fixed mirrors that are focused on the skylight. Transparent louvers made of prisms then automatically adjust to diffuse that sunlight into the atrium. Other features help distribute the light into the building’s interior, including a wall of polished aluminum panels, a reflecting pool and a chandelier made of 768 moving prism tiles. The company estimates that 75 percent of its employees can work using natural light alone.
A double façade of glass covers about one-third of the building’s exterior. The ventilated space between the two curtains of glass allows fresh air to flow throughout the building and insulates it during the cold winters. These systems—and many others—helped the Genzyme Center earn a LEED platinum rating.
California Academy of Sciences
- San Francisco, Calif.
- 370,000 square feet
- main museum exhibit halls, 1 planetarium dome,
1 rainforest dome, 1 aquarium
- Completion expected in 2008
With an aquarium, a planetarium and a natural history museum housed
in one building, the California Academy of Sciences has some unusual
energy needs. That makes it a challenge to meet the LEED requirements,
but nevertheless, the Academy is striving to make its new headquarters
the largest platinum-rated public building in the world. The undulating
roof, covered with native California plants, is designed to blend
the edifice into its surroundings in Golden Gate Park.
This “living roof” will help insulate the building,
reducing the need for air conditioning in the summer; cut storm
water runoff in half; and lower the urban heat-island effect. Environmental
engineers had to figure out how to maintain the structural integrity
of the soil bed over the sloping sides of the domes—not an
easy task given that the roof also has dozens of skylights. Letting
in the sun will help save electricity, and capturing its energy
with photovoltaic cells installed on the roof will save even more.
Solar energy should supply the building with 213,000 kilowatt-hours
of electricity per year, about 5 percent of its total energy needs.