The Burj Khalifa (previously known as Burj Dubai prior to inauguration) is a megatall skyscraper in Dubai, United Arab Emirates. Designed by Skidmore, Owings & Merrill, it is the world's tallest structure, with a total height of 829.8 m (2,722 ft, or just over half a mile) and a roof height (excluding the antenna, but including a 242.6 m spire) of 828 m (2,717 ft). It has also been the tallest building in the world since its topping out in 2009, surpassing Taipei 101, which had held the record since 2004.
Construction of the Burj Khalifa began in 2004; the exterior was completed five years later. The primary structure is reinforced concrete. Some of the structural steel for the building was salvaged from the demolished Palace of the Republic in East Berlin. The building was opened in 2010 as part of a new development called Downtown Dubai. It was designed to be the centrepiece of large-scale, mixed-use development.
The building is named after the former president of the United Arab Emirates (UAE), Sheikh Khalifa bin Zayed Al Nahyan. The United Arab Emirates government provided Dubai with financial support as the developer, Emaar Properties, experienced financial problems during the Great Recession. Then-president of the United Arab Emirates, Khalifa bin Zayed, organised federal financial support. For his support, Mohammad bin Rashid, Ruler of Dubai, changed the name from "Burj Dubai" to "Burj Khalifa" during inauguration.
The design is derived from the Islamic architecture of the region, such as in the Great Mosque of Samarra. The Y-shaped tripartite floor geometry is designed to optimise residential and hotel space. A buttressed central core and wings are used to support the height of the building. The Burj Khalifa's central core houses all vertical transportation except egress stairs within each of the wings. The structure also features a cladding system which is designed to withstand Dubai's hot summer temperatures. It contains a total of 57 elevators and 8 escalators.
Development
Construction began on 12 January 2004, with the exterior of the structure completed on 1 October 2009. The building officially opened on 4 January 2010 and is part of the 2 km2 (490 acres) Downtown Dubai development at the 'First Interchange' along Sheikh Zayed Road, near Dubai's main business district.
The tower's architecture and engineering were performed by Skidmore, Owings & Merrill of Chicago, with Adrian Smith as chief architect, and Bill Baker as a chief structural engineer. The firm had designed the Sears Tower in Chicago, a previous record holder for the world's tallest building.
Hyder Consulting was supervising engineer and NORR Group Consultants supervised the architecture. The primary contractor was Samsung C&T of South Korea, together with the Belgian group BESIX and the local company Arabtec.
Numerous complaints concerned migrant workers from South Asia, the primary building labour force, who were paid low wages and sometimes had their passports confiscated.
Conception
Burj Khalifa was designed to be the centrepiece of a large-scale, mixed-use development to include 30,000 homes, nine hotels (including The Address Downtown Dubai), 3 hectares (7.4 acres) of parkland, at least 19 residential skyscrapers, the Dubai Mall, and the 12-hectare (30-acre) artificial Burj Khalifa Lake. The decision to build Burj Khalifa was reportedly based on the government's decision to diversify from an oil-based economy to one that is service and tourism based. According to officials, projects like Burj Khalifa needed to be built to garner more international recognition and hence investment. "He (Sheikh Mohammed bin Rashid Al Maktoum) wanted to put Dubai on the map with something really sensational," said Jacqui Josephson, a tourism and VIP delegations executive at Nakheel Properties.
The tower was known as Burj Dubai ("Dubai Tower") until its official opening in January 2010. It was renamed in honour of the ruler of Abu Dhabi, Khalifa bin Zayed Al Nahyan; Abu Dhabi and the federal government of UAE lent Dubai tens of billions of US dollars so that Dubai could pay its debts – Dubai borrowed at least $80 billion for construction projects. In the 2000s, Dubai started diversifying its economy but it suffered from the 2008 financial crisis and the Great Recession, leaving large-scale projects already in construction abandoned.
Records
The Burj Khalifa set several world records, including:
Tallest existing structure: 829.8 m (2,722 ft) (previously KVLY-TV mast – 628.8 m or 2,063 ft)
Tallest structure ever built: 829.8 m (2,722 ft) (previously Warsaw radio mast – 646.38 m or 2,121 ft)
Tallest freestanding structure: 829.8 m (2,722 ft) (previously CN Tower – 553.3 m or 1,815 ft)
Tallest skyscraper (to top of spire): 828 m (2,717 ft) (previously Taipei 101 – 509.2 m or 1,671 ft)
Tallest skyscraper to top of antenna: 829.8 m (2,722 ft) (previously the Willis (formerly Sears) Tower – 527 m or 1,729 ft)
Building with most floors: 163 (previously World Trade Center – 110)
World's highest elevator installation (situated inside a rod at the very top of the building)
World's longest travel distance elevators: 504 m (1,654 ft)
Highest vertical concrete pumping (for a building): 606 m (1,988 ft)
World's tallest structure that includes residential space
World's highest installation of an aluminium and glass façade: 512 m (1,680 ft)
World's highest restaurant (At.mosphere): 122nd floor at 442 m (1,450 ft) (previously 360, at a height of 350 m (1,148 ft) in CN Tower)
World's highest New Year display of fireworks.
World's largest light and sound show staged on a single building.
Architecture and design
The tower was designed by Skidmore, Owings, and Merrill (SOM), which also designed the Willis Tower (formerly the Sears Tower) in Chicago and the One World Trade Center in New York City. Burj Khalifa uses the bundled tube design of the Willis Tower, invented by Fazlur Rahman Khan. Due to its tubular system, proportionally only half the amount of steel was used in the construction, compared to the Empire State Building. Khan's contributions to the design of tall buildings have had a profound impact on architecture and engineering. It would be difficult to find any worldwide practices in the design of tall buildings that have not been directly or indirectly influenced by his work. The design is reminiscent of Frank Lloyd Wright's vision for The Illinois, a mile-high skyscraper designed for Chicago, as well as Chicago's Lake Point Tower. When Adrian Smith was conceiving the project at SOM, he looked out his office window toward Lake Point Tower's curved three-wing layout and thought, "There's the prototype". According to Strabala, Burj Khalifa was designed based on the 73 floor Tower Palace Three, an all-residential building in Seoul. In its early planning, Burj Khalifa was intended to be entirely residential.
After the original design by Skidmore, Owings, and Merrill, Emaar Properties chose Hyder Consulting to be the supervising engineer and NORR Group Consultants International Ltd to supervise the architecture of the project. Hyder was selected for their expertise in structural and MEP (mechanical, electrical and plumbing) engineering. Hyder Consulting's role was to supervise construction, certify the architect's design, and be the engineer and architect of record to the UAE authorities. NORR's role was the supervision of all architectural components including on-site supervision during the construction and design of a 6-storey addition to the office annex building for architectural documentation. NORR was also responsible for the architectural integration drawings for the Armani Hotel included in the Tower. Emaar Properties also engaged GHD, an international multidisciplinary consulting firm, to act as an independent verification and testing authority for concrete and steelwork.
The design is derived from Islamic architecture. As the tower rises from the flat desert base, there are 27 setbacks in a spiral pattern, decreasing the cross-section of the tower as it rises and creating convenient outdoor terraces. These setbacks are arranged and aligned in a way that minimises vibration wind loading from eddy currents and vortices. At the top, the central core emerges and is sculpted to form a finishing spire. At its tallest point, the tower sways a total of 1.5 m (4.9 ft).
The spire of Burj Khalifa is composed of more than 4,000 tonnes (4,400 short tons; 3,900 long tons) of structural steel. The central pinnacle pipe weighs 350 tonnes (390 short tons; 340 long tons) and has a height of 200 m (660 ft). The spire also houses communications equipment. This 244-metre (801 ft) spire is widely considered vanity height, since very little of its space is usable. Without the spire, Burj Khalifa would be 585 metres (1,919 ft) tall. This was reported in a Council on Tall Buildings and Urban Habitat study, which notes that the empty spire "could be a skyscraper on its own". Such a skyscraper, if located in Europe, would be the 11th tallest building on that continent.
In 2009 architects announced that more than 1,000 pieces of art would adorn the interiors of Burj Khalifa, while the residential lobby of Burj Khalifa would display the work of Jaume Plensa.
The cladding system consists of 142,000 m2 (1,528,000 sq ft) of more than 26,000 reflective glass panels and aluminium and textured stainless steel spandrel panels with vertical tubular fins. The architectural glass provides solar and thermal performance as well as an anti-glare shield for the intense desert sun, extreme desert temperatures and strong winds. The glass covers more than 174,000 m2 (1,870,000 sq ft) in area. The Burj's typical curtain wall panels measure 4 ft 6 in (1.4 m) wide by 10 ft 8 in (3.3 m) high and weigh about 800 pounds (360 kg) each, with wider panels near the building's edges and taller ones near the top.
The exterior temperature at the top of the building is thought to be 6 °C (11 °F) cooler than at its base.
A 304-room Armani Hotel, the first of 4 by Armani, occupies 15 of the lower 39 floors. The hotel was supposed to open on 18 March 2010, but after several delays, it finally opened to the public on 27 April 2010. The corporate suites and offices were also supposed to open from March onwards, yet the hotel and observation deck remained the only parts of the building which were open in April 2010.
The sky lobbies on the 43rd and 76th floors house swimming pools. Floors 20 through 108 have 900 private residential apartments (which, according to the developer, sold out within eight hours of being on the market). An outdoor zero-entry swimming pool is located on the 76th floor of the tower. Corporate offices and suites fill most of the remaining floors, except for the 122nd, 123rd, and 124th, where the At.mosphere restaurant, sky lobby, and an indoor and outdoor observation deck are located respectively. In January 2010, it was planned that Burj Khalifa would receive its first residents in February 2010.
The building has 57 elevators and 8 escalators. The elevators have a capacity of 12 to 14 people per cabin, and include the world's fastest double-deck elevators, rising and descending at up to 10 m/s (33 ft/s). Engineers initially considered installing the world's first triple-deck elevators. The double-deckers are equipped with LCD displays to amuse visitors during their travel to the observation deck. The building has 2,909 stairs from the ground floor to the 160th floor.
Plumbing systems
The Burj Khalifa's water system supplies an average of 946,000 L (250,000 U.S. gal) of water per day through 100 km (62 mi) of pipes. An additional 213 km (132 mi) of piping serves the fire emergency system, and 34 km (21 mi) supplies chilled water for the air conditioning system.
Air conditioning
The air conditioning system draws air from the upper floors where the air is cooler and cleaner than on the ground. At peak cooling times, the tower's cooling is 46 MW (62,000 hp), equivalent to that provided by 13,000 short tons (26,000,000 lb; 12,000,000 kg) of melting ice in one day. Water is collected via a condensate collection system and is used to irrigate the nearby park.
Window cleaning
To wash the 24,348 windows, totalling 120,000 m2 (1,290,000 ft2) of glass, the building has three horizontal tracks, each holding a 1,500 kg (3,300 lb) bucket machine. Above level 109, and up to tier 27, traditional cradles from davits are used. The top of the building is cleaned by a crew that uses ropes to descend from the top to gain access. Under normal conditions, when all building maintenance units are operational, it takes 36 workers three to four months to clean the entire exterior.
Unmanned machines clean the top 27 additional tiers and the glass spire. The cleaning system was developed in Melbourne, Australia, by CoxGomyl, a manufacturer of building maintenance units, at a cost of A$8 million.
Features
Fountain
Outside the Burj Khalifa, WET Enterprises designed a fountain system at a cost of Dh 800 million (US$217 million). Illuminated by 6,600 lights and 50 coloured projectors, it is 270 m (900 ft) long and shoots water 150 m (500 ft) into the air while accompanied by a range of classical to contemporary Arabic and other music. It is the world's largest choreographed fountain. On 26 October 2008, Emaar announced that based on results of a naming contest the fountain would be called the Dubai Fountain.
Observation deck
An outdoor observation deck, named At the Top, opened on 5 January 2010 on the 124th floor, at 452 m (1,483 ft). It opened the 148th floor SKY level at 555 m (1,821 ft), giving it the highest observation deck in the world on 15 October 2014. However, in June 2016 the Shanghai Tower opened with an observation deck at a height of 561 metres, thus taking the title of the world's highest observation deck. Subsequently, the Burj Khalifa reclaimed the record on February 18, 2019, when it opened The Lounge observatory at 585 m (1,919 ft), which is also the highest lounge in the world.
The Burj Khalifa's 124th floor observation deck also features a so-called electronic telescope, an augmented reality device developed by Gsmprjct° of Montréal, which allows visitors to view the surrounding landscape in real-time, and to view previously saved images such as those taken at different times of day or under different weather conditions. To reduce the daily rush of sightseers, management allows visitors to purchase tickets in advance for a specific date and time, at a 75% discount on tickets purchased on the spot.
On 8 February 2010, the observation deck was closed to the public for two months after power-supply problems caused an elevator to become stuck between floors, trapping a group of tourists for 45 minutes.
When the tide is low and visibility is high, people can see the shores of Iran (which is around 153 km or 95 mi away) from the top of the skyscraper.
Park
Burj Khalifa is surrounded by an eleven-hectare (27-acre) park designed by landscape architects SWA Group. Like the tower, the park's design was based on the flower of the Hymenocallis, a desert plant. At the centre of the park is the water room, which is a series of pools and water jet fountains. Benches and signs incorporate images of Burj Khalifa and the Hymenocallis flower.
The plants are watered by water collected from the building's cooling system. The system provides 68,000,000 L (18,000,000 US gal) annually. WET Enterprises, who also developed the Dubai Fountain, developed the park's six water features.
Floor plan
Ramadan observance
On the higher floors, the sun is seen for several minutes after it has set at ground level. Those living above the 80th floor wait two extra minutes to break their Ramadan fast, and those living above the 150th floor wait three minutes.