With services risers running the full 600m+ height of the building, designing MEP systems to serve the Burj Dubai has taken great care. How will the tower be serviced?
Billed as the tallest building in the world, the task of providing MEP services to the Burj Dubai was always going to be a challenge.
The world records made by the Emaar Properties' project stretch to the services themselves, with the longest lift shaft in the world and mechanical operating pressures that would send some MEP consultants into a cold sweat.
Despite this, the mission of providing reliable and efficient MEP services for the tower has involved the use of proven technologies and off-the-shelf products - albeit under a very close and detailed design and installation process and a major logistics programme.
The original design of the MEP services systems was carried out by the Chicago office of international consultant Skidmore, Owings and Merrill (SOM). "They were the original architect, structural engineer and MEP engineer," explains Hyder Consulting Middle East senior mechanical engineer Alastair Mitchell.
As supervision consultant for the project Hyder Consulting is jointly responsible for ensuring the correct installation of the MEP services to this design. "As part of or contract with Emaar we have adopted [SOM's] design - this makes us jointly responsible for the design with SOM," adds Mitchell.
With all eyes of the world on the project, ensuring a 100% reliable system in all circumstances is of primary importance. With this in mind, one of the major decisions that was taken at the design stage was to use tried-and-tested products and systems wherever possible.
Rather than opt for radical, new technologies a base of solid electrical and mechanical design has been used for the systems, with input from the process and oil and gas industry standards and best practice referred to when the pressures and system sizes grew beyond those of a standard building services project.
"[The MEP system] is quite standard in it's design in that they haven't done anything radically different," confirms Mitchell.
The hydraulics of this building are where we differ [from a smaller building] because of the extreme height of the building; what SOM has rightly done is taken established practices but extended them a bit - we've had to push the boundaries.
They've taken established principals and refined them for the ultra high-rise sector," he adds.
This has resulted in the use of higher specification materials and products such as pumps than may normally be used in a commercial high-rise structure.
It has also meant the need for detailed stress analysis at the pipework expansion and contraction points because of the extreme nature and size of the MEP services being installed.
We're operating at higher pressures than you would normally see in the construction industry generally," explains Mitchell.
It's quite easy to specify - you specify by the design pressure - but when it comes to actually selecting the equipment there's a lot of responsibility involved in making sure that we get the right products for the application," he stresses.
All equipment used in the MEP systems has also passed anti-seismic and anti-vibration specifications that take into account the natural movement and deflection of the building.
The building is split into five zones, with the main mechanical and electrical plantrooms located at approximately 30-floor intervals. These typically feed the 15 floors above and 15 floors below.
The primary distribution route for services is through main risers within the central core of the structure, which remains the same size to level 150 despite the overall building shape tapering with height.
The smaller floor footprints at the higher levels mean that lower capacities of plant such as pumps, air handling units and heat exchangers are needed.
A central building management system (bms) will oversee the MEP system operations throughout the tower.
Local control panels will be mounted in each plantroom and the podium, these outstations will communicate with each other and the central bms control rooms over a main fibre optic backbone cabling system.
All MEP systems will be connected to the bms, which is used to control and monitor all the services distributed around the building.
The bms will interface with other systems such as fire alarms, security and the hotel management system to provide a fully integrated control and monitoring system for the entire project.
Installation of services
With the tower central to a very tight site within an inner-city location, a major logistics plan was needed to ensure build schedules could be maintained and materials and labour delivered to the correct place when needed.
Most deliveries have been made during the night and storage space has been made available to the MEP contractors within the podium and basement areas of the tower so bulk supplies of materials could be ordered.
"Great thought was given regarding the material and labour movement inside the building," assures Greg Sang, director - projects, Emaar. "For example, all materials are shifted to the job place during the night time and each contractor is given specific timings for shifting materials and labour," he adds.
Delivery of the plant to the upper levels of the building has been carried out by a mix of craning for the larger items, plus the use of temporary hoists and final lifts for smaller materials.
To enable the speed of construction to continue unhindered, the MEP contractor has opted to crane in large-scale pipes from the top of the building directly into the central core.
The structure and layout of the building have meant that the use of prefabrication was limited. "Ideally in a project of this scale you'd want to prefabricate as many services as possible and install it in big sections, but it wasn't really possible," states Mitchell.
The complex geometry of the building and compact nature of many plantrooms has meant that a lot of materials are taken to site and assembled in situ," adds Sang.
Where possible, pipework assemblies for chilled water, plumbing and drainage systems have been assembled in a specially created off-site workshop by the MEP contractor, but most is fabricated on site. All ductwork sections are being prefabricated off-site.
The fact that the structural works have always been well in advance of MEP in the tower also makes it difficult to crane large prefabricated assemblies into place," explains Sang.
Several areas of the building are being worked on simultaneously by the MEP contractor. "The risers are independently supported from the horizontal distribution," explains Mitchell.
"[The contractor] is working in many different zones at the same time in the plantrooms, distribution and the risers have gone up with the structure," he adds.
The removal of the plant at the end of its lifespan has also been considered. Plantrooms are located adjacent to the service lifts, with the elevators sized to cater for the largest section of plant that must be removed - the transformers.
The plantroom layouts have also been designed so the routing to the elevator is free of any equipment so there is no need to stop any operations while replacing equipment.
Although the building has not been assigned a sustainable building rating to date, a future assessment is planned with a view to establishing a rating based on the building design, materials and construction, reports Sang.
Several energy saving technologies have been implemented throughout the MEP services design, including the collection of air handling unit condensate water for use in the pre-cooling of Dubai Electricity and Water Authority (DEWA) mains water plus irrigation.
In addition, there is an extensive use of variable speed drives wherever possible throughout the tower, in particular on the main chilled water pumps, plumbing pumps, plus supply and exhaust fans.
Thermal wheels have been added to the air handling units in order to reclaim as much heat energy as possible and a sophisticated two-port valve control system has been added to the chilled water, air handling units and fan coil units; this includes pressure independent control valves.
The building management system will be set up to optimise energy savings between the variable speed drives and the two-port valve control system," explains Sang.
Further measures include the introduction of a system to measure supply and exhaust air rates and pressures to ensure that they are balanced throughout the various building zones and air leakage out of or into the building is minimised.
The high-specification facade system specified for the project will reduce solar heat gains, hence cooling loads thanks to a low-e coating, low U-value and low glazing shading co-efficients.
Within the electrical systems, a lighting control system has been used throughout and energy efficient T5 lamps are being installed for areas such as the car park, plantrooms and back of house areas. Electronic control gear will be used to provide lighting control.
An extensive power monitoring and metering system is being installed, plus a power correction factor of 0.95 has been applied to electrical equipment in lieu of the required 0.90, again reducing the energy usage. High efficiency, low loss resin block power transformers have been installed as standard.
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