5. Petronas Towers (Kuala Lumpur)



The Petronas Twin Towers (also known as the Petronas Towers or just Twin Towers), in Kuala Lumpur, Malaysia are twin towers and were the world’s tallest buildings, before being surpassed by Taipei 101. However, the towers are still the tallest twin buildings in the world. They were the world’s tallest buildings from 1998 to 2004 if measured from the level of the main entrance to the structural top, the original height reference used by the US-based Council on Tall Buildings and Urban Habitat from 1969 (three additional height categories were introduced as the tower neared completion in 1996).

6. Nanjing Greenland Financial Center (Nanjing)



The Nanjing Greenland Financial Center is a 89-story, 450 meter (1500 foot) tall skyscraper being constructed in Nanjing, China. The tower is the fifth tallest building in the world and second tallest in china behind the Shanghai World Financial Center.The 72nd-story observation floor, at 287 meters (940 feet) off the ground, will offer a panoramic view of the city of Nanjing as well as the Yangtze River, the Ningzheng Ridge mountains and two nearby lakes.

7. Willis Tower (Chicago)



Willis Tower, formerly named Sears Tower, is a 108-story 1,451 feet (442 m) skyscraper in Chicago, Illinois. At the time of its completion in 1973, it was the tallest building in the world, surpassing the World Trade Center towers in New York. Currently, Willis Tower is the tallest building in the United States and the fifth-tallest freestanding structure in the world as well as the fifth tallest building in the world to the roof. Although Sears’ naming rights expired in 2003, the building continued to be called Sears Tower for several years. However, in March 2009 London-based insurance broker Willis Group Holdings, Ltd., agreed to lease a portion of the building and obtained the building’s naming rights as part of the agreement. On July 16, 2009, at 10:00 am Central Time, the building was officially renamed Willis Tower.

8. Guangzhou West Tower (Guangzhou)



Being 8th highest building Guangzhou West Tower is an extremely tall public building. The energy efficiency evaluation of its façade should be different than that of ordinary public buildings. Based on the national code GB50189-2005, “Design Standard for Energy efficiency of Public Buildings”, typical meteorological yearly data for Guangzhou were used and revised according to architectural character of Guangzhou West Tower. The energy efficiency design of a single skin facade and active airflow curtain wall was analyzed by a dynamic energy simulation tool and modified weather data. The payback period of initial investment in the facade system was evaluated based on simulation results. In addition, the results confirm the façade system scheme of Guangzhou West Tower.