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Sun 2 Mar 2008 04:00 AM

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Tower task

Ongoing client changes have added to the challenge of installing MEP services on the JAL Twin Towers project in Dubai. Alison Luke finds out how MEP contractor Hastie International is meeting the demands of the project.

Ongoing client changes have added to the challenge of installing MEP services on the JAL Twin Towers project in Dubai. Alison Luke finds out how MEP contractor Hastie International is meeting the demands of the project.

As construction of the JAL Twin Towers project passes the halfway mark, ongoing client changes have made co-ordination and flexibility two key words for the MEP contractor Hastie International. Ensuring the project remains on programme while adapting the MEP services to suit the final building needs is creating specific challenges, with changes including the addition of nightclubs, restaurants and shops.

When there are civils delays in one tower we can shift labour to the other to carry on work.

Sited in a prime location on Sheikh Zayed Road, Dubai, the project comprises two multi-storey towers: a 51-storey hotel and 47-storey mixed-use building. On completion the hotel will be operated by Japan Airlines (JAL). Its mixed-use neighbour will comprise shops in the lower levels, topped by offices up to floor 26 and residential apartments on the upper storeys. At the rear of the site, two 13-storey car parks will serve the towers individually.

The first project that Australian contractor Hastie has undertaken in Dubai outwith a joint venture since it established in the Emirate in 2006, the firm won the contract by competitive tender. It's contract includes the installation and commissioning of temporary power, plus the full final MEP installation works including fire safety services, the building management system (bms) and emergency services, to a design by MEP consultant Dimensions Engineering Consultants (DEC).

Due to the amount of changes that have been made to the original design, Hastie has six draughtsmen permanently on site to check and amend the installation drawings as needed prior to approval from DEC.

In order to complete the project on schedule, Hastie has subcontracted Dubai-based MEP contractor Omega Engineering to carry out the plumbing and electrical installations. "[The work] was originally to be done inhouse, but it was Hastie's first project [in Dubai] and they were not ramped up enough yet to get [a sufficient] labourforce together.

To meet the schedule for the client we had to get a subcontractor," explains Hastie senior project manager Robert Studd. Honeywell is carrying out installation of the bms under a separate subcontract package to Hastie.

Servicing the towers

The two towers will operate independently once complete and the MEP services design reflects this, with two autonomous systems being installed for the individual towers.

Air conditioning is provided by district cooling, with the mixed-use tower having a 2,370kW demand and the hotel requiring 4,200kW of cooling. To meet these needs, the contractor has tapped into the main Tabreed district cooling supply that runs parallel to Sheikh Zayed Road. The chilled water from the district cooling system will be passed through primary heat exchangers in basement plantrooms in each of the car parks.

These in turn will serve secondary heat exchangers in each of the towers, which will supply cold water to a number of air handing units throughout the buildings to feed local fan coil units in the individual areas.

The temporary electricity supply is being provided by a dedicated transformer fed from the Dubai Electricity and Water Authority (DEWA) mains supply. DEWA carried out the high voltage installation of the system, with Hastie completing the low voltage works.
For the final installation, the mains supply will feed transformers in the basement of each car park that serve the main distribution boards. Power from here will be fed underground to switchrooms in the towers before being distributed in risers by busbar to each floor.

In the mixed-use tower, eight 1,600A busbars will carry power through the central risers to local distribution boards at each floor. From here the electricial supply will be distributed both underfloor and in false ceilings throughout the floors. Having a larger electrical load, the hotel power will initially be distributed by six 1,600A and two further 2,000A busbars before being distributed locally in the same way as the mixed-use tower.

Both buildings have standby generators to serve the emergency services. These have capacities of 720kW in the case of the mixed-use tower and 1,250kW for the hotel.

Service changes

The addition of facilities such as restaurants and nightclubs has meant significant design changes to the MEP services. The capacity in the mixed-use tower for example has risen from 7,430A to 12,800A; in the hotel a rise in capacity from 11,200A to 13,600A must be accounted for. The ductwork and exhaust fans have also needed alterations due to the increased airflow rates needed from such establishments explains Studd.

As the revised designs have yet to be finalised, Hastie has had to remain flexible in its programming to ensure the overall project schedules can be maintained. To date the MEP services work has comprised mainly of the installation of ductwork and fan coil units, plus some work in the main risers. Installation of the plantrooms has yet to begin, however it is expected that this will become possible within the next few weeks.

Each tower has five plantrooms, one in each basement and the others distributed throughout the height of the building. Some external cladding has been left off to enable delivery of the plant once the final system designs are complete, with the civil contractor currently building landing platforms to enable this to be carried out. Goods lifts running through the plantrooms will enable the removal and replacement of equipment at the end of its service life.

In the lower floors of the towers plastering of walls has begun, the ceiling contractors will follow, which will then enable the second-fix MEP services to be completed.

The MEP contractor is working closely with the main contractor to ensure that the services design can be met and all penetrations, sleeves and conduits fitted where needed. "All of our conduits have to be cast into the floor slabs, so as [the main contractor is] steel fixing we are fixing the conduits in - that's fairly intricate," explains Studd.

There's a dedicated crew that works at that face level and those guys are permanently there," he adds. The use of the same staff for this task throughout the project and the repetitive nature of the work has enabled an increase in productivity as the buildings progress Studd reports.

The fact that the towers are being constructed almost simultaneously has helped Hastie maintain flexibility of programming on the project. Initially the firm divided the project work into two, with separate teams on each tower, but in order to deal with the changes it now has a combined project team, with managers and supervisors overseeing each individual area such as plumbing and electrical across the entire project.
This is enabling the contractor to redistribute staff around the site to work on areas as they become available.

"It's the way the project has progressed, we didn't find it beneficial [to have separate teams for the two buildings] because we're having so much stop-start due to the changes, while now often we're shifting our workers between the two towers," explains Studd. "We've got people working on the same level in both towers at the same time, but there could be delays in the civils work in one side so we can just shift them across to [the other tower] so they can continue work...it's a co-ordination issue."

Close liaison with the main contractor and ongoing programme co-ordination has been vital on the project and will continue in order to facilitiate the client needs stresses Studd. And with flexibility a key word within the team, the successful completion of the project is assured.

PROJECT: JAL Twin TowersClient:Ghassan Ahmad Saud Al Khalid
Project Manager/Management Contractor:Projacs
Main Contractor:ACICO International

Contracting

Architect:BRT Engineering
M&E Consulting Engineer:Dimensions

Engineering Consultants

MEP contractor:Hastie International
Lighting Designer:Dabbas

Contract details

Tender date:July 2006
Construction start date:October 2006
Contract period:24 months
Completion date:December 2008

Suppliers

AHUs:Trane
Air conditioning:Trane
BMS:Honeywell
Boilers:Viessmann Middle East
Cable:Ducab, Electra
Control valves:Honeywell
Controls:Honeywell
Drainage:Hepworth
Ductwork:KAD Air Conditioning
Electrical distribution:ABB
Emergency luminaries:Thomas Beto
Extract fans:Penn Barry USA, Penn Wolter Germany
Fan coil units:Trane
Fire alarm/detection:Honeywell
Floor grilles:Tecnalco
Heat exchangers:Sondex
HV switchgear:ABB
Insulation:Armaflex
Lighting controls:Delmatic
LV switchgear:ABB
Power busbar:Henikwon
Public address system:Honeywell (Urmet-Italy)
Pumps and pressurisation:ITT Bell & Gossett
Security equipment:Honeywell
Sprinklers:Reliable - USA
Standby generation:Cummins
UPS:
Emerson - Liebert
VAV boxes:Metalaire
Voice & data equipment:Brand-Rex
Water heaters:Sanifirst

Costs

Project cost:US $163 million (AED600 million)
MEP services cost:
US $37 million (AED135 million)

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