Kingdom Tower - Design

Design

The triangular footprint and sloped exterior of Kingdom Tower is designed to reduce wind loads; its high surface area also makes it ideal for residential units. The overall design of the tower, which will be located near both the Red Sea and the mouth of the Obhur Creek (Sharm Ob'hur) where it widens as it meets the Red Sea, as well as having frontage on a man-made waterway and harbor that will be built around it, is intended to look like a desert plant shooting upwards as a symbol of Saudi Arabia's growth and future, as well as to add prominence to Jeddah's status as the gateway into the holy city of Mecca. The designer's vision was “one that represents the new spirit in Saudi Arabia" (Smith). The 23 hectare (57 acre) area around Kingdom Tower will contain public space and a shopping mall, as well as other residential and commercial developments, and be known as the Kingdom Tower Water Front District, of which, the tower's site alone will take up 500,000 m2 (5,381,955 sq ft). As with many other very tall skyscrapers, including the Kingdom Centre in Riyadh, which is generally considered to have sparked the recent significant commercial developments around it in the district of Olaya, much of the intention of Kingdom Tower is to be symbolic as well as to raise the surrounding land value rather than its own profitability. To that effect, the tower's architect, Adrian Smith, said that the tower "evokes a bundle of leaves shooting up from the ground–a burst of new life that heralds more growth all around it". Smith states that the tower will create a landmark in which it and the surrounding Kingdom City are interdependent. Talal Al Maiman, a board member of Jeddah Economic Company, said, “Kingdom Tower will be a landmark structure that will greatly increase the value of the hundreds of other properties around it in Kingdom City and indeed throughout North Jeddah.” The concept of profitability derived from building high density developments and malls around such a landmark was taken from the Burj Khalifa, where it has proven successful, as its surrounding malls, hotels and condominiums in the area known as Downtown Dubai have generated the most considerable revenue out of that project as a whole, while the Burj Khalifa itself made little or no profit.

The building will have a total of 59 elevators, five of which will be double-deck elevators, as well as 12 escalators. It will also have the highest observation deck in the world, to which high speed elevators will travel at up to 10 meters (33 feet) per second (slightly over 35 km/h (22 mph)) in both directions. The elevators cannot go faster because the rapid change in air pressure over that much distance would be nauseating; at 914 m (3,000 ft), the air pressure is over 10 kPa (1.5 psi) lower than at ground level (about 10% less air pressure). They must also be efficient so the cables are not unbearably heavy. Even as such, the elevator distance limit is about 570 metres (1,870 ft) before the cables become inevitably too heavy and the motor size impractical; Kingdom Tower will have three sky lobbies where elevator transfers can be made, no elevator will go from the bottom to the highest occupied floor. No official floor count has been given, however Smith stated in a television interview that it will be about 50 floors over the Burj Khalifa, which has 163 occupied floors, leading to the inference that Kingdom Tower will have well over 200 floors. The tower will also feature a large, roughly 30 m (98 ft) diameter outdoor balcony, known as the sky terrace, on one side of the building for private use by the penthouse floor at level 157; it is not the observation deck. It was originally intended to be a helipad, but it was revealed to be an unsuitable landing environment by helicopter pilots. The building's large notches will also serve as shaded terraces for other areas of the tower and the exterior of the building will use low-conductivity glass to save on cooling costs by reducing thermal loads. In addition, the lower air density, exacerbated by the thin desert atmosphere, will cause the outdoor air temperature towards the top of the tower to be lower than the ground level air, which will provide natural cooling. There is also significantly more air flow (wind) at heights, which is very strong at one kilometer and had a large impact on the structural design of the tower. The Burj Khalifa actually takes in the cooler, cleaner air from the top floors and uses it to air condition the building. Kingdom Tower will be oriented such that no façade directly faces the sun; it will also use the condensate water from the air conditioning system for irrigation and other purposes throughout the building.

Chicago based Environmental Systems Design, Inc. will provide mechanical, plumbing, electrical and fire protection engineering, as well as teledata, audio/visual, security systems and acoustics. Langan International, together with structural engineer Thornton Tomasetti, will be responsible for geotechnical engineering as well as some ground level site work such as transportation engineering and parking, including the design of the proposed 3,000–4,700 car underground parking garage that will be located near, but not under the tower for terrorism reasons. Langan also designed the tower's foundation, which has to be able to support the tower despite the less than optimal subsurface conditions, such as soft rock and permeable coral, which could cause the piles to settle. Thornton Tomasetti has provided the structural engineering for two of the previous world's tallest building title holders, the Petronas Towers in Kuala Lumpur, and the Taipei 101 in Taiwan, as well as the under construction Pingan International Finance Center in Shenzhen, which will be the tallest building in China after completion. Saudi Binladin Group is the largest construction firm in the Middle East, with over 35,000 workers and hundreds of projects. They recently constructed the topped-out 601 m (1,972 ft) Abraj Al-Bait Clock Tower in Mecca, which is the tallest building in Saudi Arabia and second tallest in the world, as well as the largest skyscraper in the world by floor area and volume. Aside from buildings, the firm has also constructed many major infrastructure projects, such as the King Abdulaziz (Jeddah) International Airport expansion and the 775 km (775,000 m) six lane Al Qassim Expressway through Saudi Arabia. Saudi Binladin Group is owned by the family of the late al-Qaeda leader Osama bin Ladin, whom the family disavowed long before his death. Nonetheless, it has sparked some minor media buzz. When asked his thoughts about this in an interview, Adrian Smith simply stated that they are the largest construction firm in the Middle East, most significant work in Saudi Arabia was done by them, and that it is a very large family that shouldn't be stereotyped by one of its members. Furthermore, in January 2012, New York City judge George B. Daniels ruled that no charges could be filed against SBG to repay the victims of 9/11 as there is no evidence of the construction firm financially supporting bin Laden after he was removed as a shareholder following the 1993 World Trade Center bombing.

“An elegant, cost-efficient and highly constructible design.”

— Adrian Smith, architect of Kingdom Tower

In addition to its primary functions, the building is slated to include a significant amount of retail as well as a wide variety of other unique ammentities with the intention that it functions as a nearly self-sustaining entity, approaching the concept of a "vertical city". The building's design has been applauded as simplistic and buildable, yet bold, brilliantly sculpted, and high-tech, with AS + GG describing it as "an elegant, cost-efficient and highly constructible design." The estimated construction cost of US$1.23 billion, which is less than that of the Burj Khalifa (US$1.5 billion), can be attributed to cheap labor in the Middle East, particularly Saudi Arabia, and that three shifts will work around the clock to expedite the process. Construction costs have also declined since the global financial crisis.

“At extreme heights, the main challenges are along practical and architectural lines, not material or structural.”

— Bob Sinn, principal of Kingdom Tower engineering firm Thornton Tomasetti

In July 2011, a report by consultancy EC Harris found that Saudi Arabia is the cheapest country in the Middle East to build in, half as expensive as Bahrain, and 34% cheaper than the United Arab Emirates, where Burj Khalifa is located. The future towers' site is located in very close proximity to King Abdulaziz (Jeddah) International Airport, whose runways nearly align with the towers' site, which will have an effect on the airspace. While skyscraper experts have stated that towers well over one kilometer, even two kilometers (6,562 feet) high, are technically buildable, physical sustainability and practicality issues come into play in towers of this height. From a real estate perspective, it is considered virtually impossible to create enough demand to justify such a tower, but that at some point someone with a great excess of money will likely do it anyway. As for physical restraints, Bart Leclercq, head of structures for WSP Middle East recently said, “I truly believe that 1 mile—1.6 kilometres—is within range. Over that, it may be possible if there are improvements in concrete quality. But 2km is too big a figure –it’s just a step too far at the moment.”

“Kingdom Tower’s height is remarkable, obviously, but the building’s iconic status will not depend solely on that aspect. Its form is brilliantly sculpted, making it quite simply the most beautiful building in the world of any height.”

— Talal Al Maiman, board member of Jeddah Economic Company

Sustainability of such a tall building would include issues such as vertical transportation limitations, with elevators only being able to go so far, building sway, caused by wind, and supercolumn settling, which is where the steel columns settle more than the concrete core and cause the floors to be unlevel. Additionally, a very large core size is required in very tall buildings to support the structure as well as to house the large number of elevators needed. The core size consumes a significant amount of the space on the lower and middle floors. One of the ways Kingdom Tower attempts to overcome these issues is with its smooth, sloped-exterior design, which, although more expensive to build, offers superior aerodynamic performance over "stepped" designs such as the Burj Khalifa, allowing it to have a more conservative core overall. This was determined by wind tunnel tests performed at Burj Khalifa. Kingdom Tower will also utilize copious stiffening materials to prevent the excessive sway that would otherwise make the occupants of upper floors nauseous on windy days, including very high strength concrete that will be up to several feet thick in certain parts of the core. This, along with the highly integrated steel frame and shear walls, is also intended to prevent catastrophic failure of the structure in the event of a terrorist attack. Traditionally, these physical constraints, namely the space consumed by elevators, were considered to make a building become increasingly less profitable past 80 floors or so. More recently, it has been the advent of truly mixed-use design such as Shanghai Tower and Burj Khalifa, as well as improved building technology, that have outdated this rule of thumb, which generally applied to single use buildings.

“Is there such as thing as too high? I think mankind is always going to be challenged by finding the next frontier. I think there’s also a market -people will always want to be in the world’s tallest tower.”

— Bart Leclercq, head of structures for WSP Middle East

Both towers share a similar three-petal triangular footprint for stability and a tapering form, with sheer height and wind being the biggest structural design challenge. The smooth, sloped façade of Kingdom Tower particularly induces a beneficial phenomenon known as "wind vortex shedding," whereas normally when wind swirls around the leeward side of a building, rushing in from both sides to fill the low pressure zone, it would create tornado-like vortices, which would rock the building from side to side due to variations in pressure, direction, and velocity, the dynamic façade of Kingdom Tower creates an infinite timing differential (whereas Burj Khalifa is limited by the number of steps) in air pressure exertion in any one particular direction, thus creating a more stable structure, as there is no broad area of outstanding pressure or depression at any given time. Put simply, a smooth taper is more aerodynamic than an irregular or jagged taper, while both are advantageous over rectangular geometries. At Kingdom Tower's height, it is considered essentially unfeasible to use a traditional square design.

To overcome elevator issues, the tower will use its large number of efficient elevators as well as its three sky lobbies, which allows transfers to be made between elevators serving a specific area with no elevator being overburdened. Much was learned from Burj Khalifa that helped with the design of Kingdom Tower not only structurally, but in methods for designing practical mechanical, electrical, and plumbing (MEP) systems, as well as adhering to local regulations and international building codes. Despite all the physical challenges, Adrian Smith states that practicality is still the greater challenge over structural durability, even in such supertall designs, and that as with all buildings, Kingdom Tower's form and was primarily derived respective of what the building's uses would be, then in accordance with the structural factors that would have to be considered to deliver it.