(AKA 30 St. Mary Axe, London) 591 ft. tall 41 stories 6,561 sq. ft. Architect: Norman Foster Developer: Swiss Re Completed: 2004 Features: Natural daylight and ventilation. Testing innovative vegetated facade panel or "green wall" known as a "core hydraulic integrated arboury panel." Expected to use less than half the energy consumed by air-conditioned office towers.

597 ft. tall 46 stories 860,000 sq. ft. Architect: Norman Foster Developer: Hearst Corp. Features: Atrium is paved with heat conductive limestone over tubing with circulating water for cooling and heating. Rain collected on roof is stored in basement tank for cooling system. 85% of structural steel contains recycled material. New York City's first LEED-Gold skyscraper. Completed: first six stories in 1928; additional tower in 2006

672 ft. tall 62 stories 770,000 sq. ft. Completed 2007 Architect: Solomon Cordwell Buenz Developer: Magellan Development Features: Chicago's tallest all-residential tower. First Midwestern tower to achieve LEED Silver.

(AKA Salesforce Tower London) 755 ft. tall 46 stories 133,976 sq. ft. Architect: Kohn Pedersen Fox Developer: Heron International Completed 2011 Features: 18,492-gallon aquarium in atrium stocked with 1,200 tropical fish of 67 species. Triple-skin glazed facade with photovoltaic cells to generate electricity and act as solar shield, reducing heat absorption. Natural daylight.Internal air handling plant rooms for heat recovery and ice storage facility and adiabatic cooling to reduce energy consumption. BREEAM rating: Excellent.

975 ft. tall 92 stories 576 apartments 1.3 million sq. ft. Architect: Fender Katsalidis Architects Developer: Daniel Grollo/Grocon Construction, Tab Fried Completed 2006 Features: Eureka Skydeck 88 observation deck on 88th floor is highest public vantage point in a building in the Southern Hemisphere. "The Edge," a glass cube, moves out over the edge of the building. Top 10 floors have 24-carat gold plated glass windows. Low-emission, natural materials used throughout. Facade is made of minimum amounts of aluminum and glass thickness. Double-glazed windows reduces the need for heating and air-conditioning systems.

1,012 ft. tall 87 stories 589,602 sq. ft. Architect: Renzo Piano Developer: Sellar Property Group, Qatar Completed 2013 Features: Sophisticated glazing system reflects sunlight and sky so the building changes with the seasons and is energy efficient. Combined heat and power plant contained within, operating on natural gas from the British National Grid; fuel is efficiently converted to electricity and heat is recovered from the engine to provide hot water for the building.

(AKA Guangdong Tobacco Building) 1,016 ft. tall 71 stories 2.3 million sq. ft. Architect: Skidmore, Owings & Merrill with Adrian D. Smith and Gordon Gill Developer: China National Tobacco Corp. Completed: 2011 Features: Clean tech skyscraper. Most energy-efficient super-tall building in the world with largest radiant cooling system, wind turbines and solar collectors. Designed to minimise hard to the environment and to extract energy from natural and passive sources surrounding it.

China World Trade Center 3 Beijing, China 1,083 ft. tall 74 stories 280,000 sq. ft. Architect: Skidmore, Owings & Merrill Developer: China World Trade Center Completed: 2010 Features: LEED Gold Core & Shell certified. Energy efficient LED lighting on exterior and crystalline facade covered in fritted glass and metal fins that act as vertical sunshades, maximizing interior daylighting. Rooftop features pine garden; building also includes grand ballroom, retail podium and landscaped water garden. Billed as "the Place Where China Meets the World."

1,588 ft. tall 118 stories Architect: Kohn Pederson Fox Associates and Wong & Ouyang HK Ltd. Developer: Sun Hung Kai Properties Completed: 2010 Features: Certified Hong Kong Building Environmental Assessment Methods (HK BEAM) Platinum. LEED Gold certification. Includes sky100 Hong Kong Observation Deck and Ritz-Carlton Hotel as well as offices and retail. Hosts the largest light and sound show on a single building. Also features world's highest swimming pool.

1,614 ft. tall 101 floors sq. ft. Architect: Kohn Pedersen Fox Developer: Morgan Stanley, Chinese, Japanese and Hong Kong banks Completed: 2008 Features: LEED Gold pre-certified. Begun in 1997 before environmentalism became a building concern, yet its structural design reduces the amount of structural material and thus embodied energy in the design overall.

1,667 ft. tall 101 floors 2.08 sq. ft. Completed: 2004 Architect: C.Y. Lee & Partners Developer: TFCC Features: Taipei 101 was designed before the release of LEED and Taiwan’s own green building rating system (EEWH),but the project team later incorporated green features into the design. TFCC chose LEED for Existing Buildings: Operations & Maintenance certification. Taipei 101 is also in the top 30% of high-rise office buildings as benchmarked by the Energy Star database, reducing energy consumption by 33.41 million kWh per year and saving more than $2 million per year. Low-flow water fixtures and water management systems reduced water usage by at least 30% compared to average building consumption, saving about 28,000,000 liters of potable water annually.

1,776 ft. tall 104 stories 3 million sq. ft. Architect: Skidmore Owings & Merrill Developer: The Durst Organization, The Port Authority of New York and New Jersey Features: LEED Gold Core & Shell certified. State-of-the-art life-safety systems. PureCell phosphoric acid fuel cells generate 4.8 MW of power. Materials used are 80% recycled. Uses off-site wind and hydroelectric power. Windows designed to allow maximum daylight to pass through.