Commerce conservation drive
The Dubai Chamber headquarters is a prime example of how massive energy and water savings can be achieved in an existing facility. MEP Middle East reports.
Anyone who believes that it's impossible to make significant water and power savings on an existing building without a large financial investment should speak to Jagath Gunawardena. As chief engineer at the Dubai Chamber (DC) head office he has instigated and overseen changes over the past ten years that have resulted in a 60% reduction in water use in the facility and a power consumption rate that is far below the national average. And yet more changes are planned.
In a move instigated by the DC director general Hamad Mubarak Buamim, Dubai-based consultancy Global Tech has recently completed an environmental audit of the building to determine the achievements so far and offer suggestions for future adaptations. The results are even more impressive given the age and operation of the building. "This is the first time that an independent audit has been carried out on a working building in Dubai. It's a positive example of someone taking the initiative for ten years [to reduce their water and power use] and they actually have the records to prove that the water and energy consumption has gone down," stressed Global Tech director Joshua Ady.
The DC building is located on the Deira side of Dubai Creek and comprises two main structures: an 18-storey building with offices, conference rooms and supporting facilities; and a three-floor building that includes a 700-seat state-of-the art auditorium. Unlike a conventional office building, it is classed as an institutional facility and serves a number of different purposes including hosting conferences. "This is not a straightforward office, we have 11 venues for conferences, including a 700-seat auditorium and 200-seat conference room, and we host around 500-600 events per year," stresses Gunawardena. The mixed-use nature of the facility has added to the challenges involved in maximising efficiency of the MEP services.
The improvements to energy and water use have not simply been possible because the building and its services were poorly designed initially. Indeed the audit has shown that structural elements such as the glass curtain walling and roof insulation meet ASHRAE standards set in 2004. "A high-calibre UK-based consultant designed the MEP system and 60% of it is well designed," states Gunawardena. "The design did have some regional flaws and the main air conditioning system was not exactly well designed in terms of energy efficiency, so the whole system has been modified to compensate for this," he adds.
ÃƒÂ¢Ã¢â€šÂ¬Ã‚Â¢ The installation of air-cooled chillers, which has totally eliminated the use of water for cooling purposes. This enables the DCCI to conserve around 50m3/day of water and has also avoided the generation of large quantities of wastewater.
ÃƒÂ¢Ã¢â€šÂ¬Ã‚Â¢ The collection of condensate water from the air handling units for use in the building's fountain; around 0.85 million litres are recovered annually.
ÃƒÂ¢Ã¢â€šÂ¬Ã‚Â¢ The installation of a plc-based control system to prevent urinal flushing when they are not in use. The system is linked to the bathroom lights and the flushing system is automatically deactivated when lights are off; this has enabling savings of around 30,000 litres/day to be made.
ÃƒÂ¢Ã¢â€šÂ¬Ã‚Â¢ All urinals have been fitted with infrared detectors that activate flushing only when they are in use. As the occupancy rate in some areas of the building are small this has reduced flushing rates from ten to almost three time per hour, saving 30 litres/day per urinal, a total of about 12,000 litres/day.
ÃƒÂ¢Ã¢â€šÂ¬Ã‚Â¢ Automatic faucets have been installed in all washrooms. These have an infrared sensor to detect users, allowing water to run only when required. An estimated 1,000 litres/day of water is saved by using these products.
With air conditioning being the major user of energy as is the norm in Middle East buildings, the initial focus for Gunawardena and the DC engineering team when aiming to reduce power use was to increase the operational efficiency of this system. Gunawardena began work at the DC during the final stages of the MEP installation, however contractual reasons meant that no changes could be made to any systems for the first three years of the building's occupation. This period of operation enabled the DC engineering team to carry out an internal audit and identify the areas that were using the largest amounts of energy.
"In 1998 we made some major alterations [to the MEP system and its operation] and immediately saw the results," stresses Gunawardena. One of the major changes in the operation of the air conditioning system was the reduction in use of chillers - since 1998 no more than four of the eight chillers installed have been run simultaneously to meet the cooling load needs. "To date we are using 50% of the design capacity of the air conditioning system, even in peak summer," Gunawardena confirms.
Each 500kW chiller is served by two reciprocating compressors. By adopting an air cooling system to reject heat from the condensers the need for evaporative cooling towers was eliminated and around 20,000 litres/day of water saved. Savings in power have also been achieved by operating the chilled water system on the principles of constant water flow, with only one of the four installed circulating pumps required to meet constant cooling loads. The estimated specific energy consumption in the building is around 6.5 kWh/m2/year, which is significantly lower than the 150 kWh/m2/year reported for hot climate zones in the USA and 250 kWh/m2/year average in the UAE.
The air conditioning is linked into a central building management system (bms) and is programmed to cool areas only during the hours of occupation. The bms is similarly used to monitor and optimise energy consumption throughout the building as well as cater for safety and security within the facility.
While reducing power consumption has been a major focus for the DC engineering team, they have proved equally successful at lowering the water use in the facility. A series of measures taken over the past ten years has seen water consumption fall from around 20 million litres per year to 7 million litres per year despite a rise in building use (see box: ÃƒÂ¢Ã¢â€šÂ¬Ã‹Å“Water saving measures'). The audit confirmed that the per capita consumption in the building is around 170 litres/day, significantly lower than the 250 litres/person/day UAE average.
"We have proved that in an office building we can save 50% of water by using different methods," states Gunawardena. Initial steps involved ensuring a good maintenance programme was in place to prevent and repair any leaks, this was followed by the installation of water-saving technologies such as infrared detectors on the taps and urinals. The toilet flushing capacities have been reduced simply by placing filled litre bottles in the cisterns.
ÃƒÂ¢Ã¢â€šÂ¬Ã‚Â¢ In order to optimise the chiller operating loads a maximum of three out of the site's eight chillers are operated at any point to meet the building's required cooling loads.
ÃƒÂ¢Ã¢â€šÂ¬Ã‚Â¢ Preventative maintenance practices have been implemented to avoid breakdowns and improve the building's plant efficiency.
ÃƒÂ¢Ã¢â€šÂ¬Ã‚Â¢ The entire chilled water line has been insulated with glass wool material to ASHRAE 2004 standards.
ÃƒÂ¢Ã¢â€šÂ¬Ã‚Â¢ The cooling demands are being met by the operation of a single 22kW chilled water circulation pump. By bypassing the additional 22 and 30kW pumps installed at the construction phase, around 100,000kWh of energy are saved annually.
ÃƒÂ¢Ã¢â€šÂ¬Ã‚Â¢ Room and zone temperature control sensors have been installed in order to reduce cooling loads in off-peak hours; the main temperature is allowed to increase to 27Ãƒâ€šÃ‚Â°C in non-operational hours from 22Ãƒâ€šÃ‚Â°C during working hours.
ÃƒÂ¢Ã¢â€šÂ¬Ã‚Â¢ A chilled water chemical treatment programme has been adopted to minimise energy loss due to the formation of scale in the chilled water pipelines.
ÃƒÂ¢Ã¢â€šÂ¬Ã‚Â¢ The original building envelope and roof insulation conform to ASHRAE 2004 standards for thermal transmittance, solar heat reflectance and solar heat absorption properties.
ÃƒÂ¢Ã¢â€šÂ¬Ã‚Â¢ A variable air flow supply system has been installed to serve the building peripherals.
ÃƒÂ¢Ã¢â€šÂ¬Ã‚Â¢ Energy management code of practices have been implemented across the building, these include using alternative low energy lighting systems in the auditorium during maintenance and cleaning periods.
One of the more unusual approaches taken has been the collection of condensate water from the central air handling units to serve the outdoor fountain. Water is collected in two condensate collection tanks in the basement plantroom and supplied to the fountain as needed. The system was established in 1994 and now around 0.85 million litres of water are being collected annually for this purpose, reducing the amount of mains water needed, and this method is one which could be easily repeated in other buildings Gunawardena stresses. "This is from 11 hours [daily] operation of air conditioning in a 20,000m2 building - imagine if you collected the water from a large shopping mall where hot air and humidity are being carried in by the people, if that was used the advantages would be huge," he states.
In the building's gardens DC uses treated sewage effluent (TSE) supplied by the Dubai Water and Electricity Authority. However the use of dip and sprinkler irrigation methods for watering the plans and lawns are ensuring a water usage that is around 300% lower than UAE average values for these purposes.
Global Tech has now finalised its report for the building. Recommendations for future changes include the calibration of temperature and damper sensors on the chiller and air conditioning units; the use of outdoor air during winter months to help cool the building by the installation of a fresh air supply control system; the use of plc-based occupancy sensors to automatically control lighting use in some areas; and the installation of efficient reciprocating chillers at the end of the life of the existing plant.
But Gunawardena, one step ahead, already has change in mind. These include maximising the energy consumption of the building's lifts. "With lifts, the highest energy use is when they are going down empty, so we are looking at the number of people using lifts and attempting to rebalance the lifts' weight to saving energy."
A preliminary health, safety and environmental manual has been prepared and provided to senior staff and the DCCI is currently aiming for ISO 14,001 certification.
Project manager: KEO
Main contractor: Al Futaim Wimpy
Architect: Nikken Sekkei
M&E consulting engineer: Kennedy & Donkin
MEP contractor: Lunar Drake & Scull
Lighting designer: Lunar Drake & Scull (GE, Concord)
Tender date: October 1991
Construction start date: January 2002
Contract period: 24 Months
Completion date: December 1994
Boilers: IMI Rycroft
Cable management: AT & T
Control valves: Siemens
Electrical accessories: Dorman Smith
Electrical distribution: Dorman smith
Emergency luminaries: Thorn Electric
Extract fans: Nuaire
Fan coil units: Interklima
Fire alarm/detection: Gent UK
Floor boxes: Barton Engg
Floor grilles: Trox Technik
Heat exchangers: Kaori BPHE
Insulation: Arabian Insulation Manufacturing
Lighting controls: Siemens
Luminaires: GE, Concord
LV switchgear: Dorman Smith
Power busbar: Westinghouse
Pumps: SPP, Crane
Security equipment: Northen computers
Sound attenuation: Trox Technik
Standby generation: Caterpillar
UPS: Merlin Gerin
VAV boxes: Trox Technik
Water heaters: IMI Rycroft
MEP services: US $12.8 million (AED47 Million)