Intelligent designing

With sustainable design now a hot topic in the Middle East, Dubai already houses one of the most environmentally friendly building's in the world. Alison Luke reports from the region's first LEED Platinum-rated building.

ANALYSIS, MEP

South-West of Dubai, long past the more recognised of the Emirate's new projects stands one building that could help form the long-term future of the Middle East construction trends. While the construction industry is beginning to recognise that there is a need to consider energy use and sustainability of buildings, Pacific Controls has taken the bold move of constructing its own Middle East headquarters to as high a level of sustainable design as possible.

Energy efficiency is a common theme throughout the MEP systems and the firm has embraced the use of alternative energies and new technologies such as solar power and absorption chillers, proving their usefulness in the region. The building is the first in the Middle East to achieve the Platinum rating under the USA Green Building Council's Leadership in Energy and Environmental Design (LEED) awards. Even more impressive is the fact that it is only the 16th building worldwide to achieve this accolade.

The global automation solutions firm appointed the Confederation of Indian Industry's (CII) Green Building Business Centre as consultant to ensure that it could achieve the maximum LEED rating for its new Dubai base. Construction work on the five-storey building began in November 2005.

Achieving the Platinum LEED rating has involved every aspect of the building's design. All materials have been sourced within a 200km diameter of the building and many materials used are from recycled sources.

"We have used a lot of recycled products here including furniture from the previous office; some of this has been used directly, other pieces have been cut down and the wood reused as kitchen cupboards for example," explains Samod Kanjoor, Pacific Controls' project engineer. The materials chosen for construction also play their part in the energy efficiency of the MEP services.

The distinctive curved facade of the crescent-shaped building is formed with low-emissivity glass, enabling maximum light to enter while minimising the solar heat gains, hence reducing the electrical lighting and cooling loads.

As well as office space, the building includes a warehouse and workshop for the production and supply of automation products; plus four command control centres for monitoring of building services and mobile assets of the firm's government and private sector clients in the region using Pacific Control Privet cellular network. It is also a showcase of Pacific Controls' specialist building management and control products, the use of which here will add to the efficient use of energy.

All building systems such as hvac, access controls, cctv, fire alarms, audio/visual, chillers, lighting and power are connected to the IP backbone. These are fully integrated using open protocols such as BACnet, LON, Modbus and web services such as XML/SOAP/HTTP. All energy consumption is monitored and tracked in real-time to ensure that the consumption is optimised and targetted costs are achieved.

One of the systems controlled in this way is the lighting. Lighting throughout the office areas is primarily supplied by 14W tungsten fluorescent lamps reports Kanjoor. These are timer-controlled to operate only during office hours and there is not a conventional light switch to be found in the building, instead occupants will have an icon on their pc to switch off the lights in their area as they turn off their computers to leave. "All lights are controlled by our intelligent IP lighting control system," explains Kanjoor, "Each circuit will have a digital output and that will be controlled by the IP lighting control system."

Controls form only part of the lighting design's contribution to the LEED status; power for the system is provided primarily by rooftop photovoltaics (see box, 'Maximising solar power for lighting').

Solar energy is also used for the air conditioning system in the building. This is served by a combination of solar thermal panels and a co-generation vapour absorption chiller to ensure maximum effiency of operation (see box, 'Heating up for cool air conditioning'). As the largest user of energy within a Middle East building, the air conditioning system was carefully designed to reduce the use of energy wherever possible.

Two rooftop fresh air handling units feed fresh air into 14 air handling units throughout the building. Each of the main units serves half of the building and each includes two heat recovery wheels which use the exhaust air to precool incoming fresh air. The amount of supply air is again closely controlled via the IP hvac control system. In accordance with LEED requirements, CO2 sensors are positioned throughout the building above false ceilings, it is readings from these feeding back into the IP hvac control system that determine the operation of the supply and return air fans.

"We have two fans - one for supply and one for return - and both are controlled with variable frequency drives," explains Sanjoor. "And we have carbon dioxide monitors all over the building ...that take the exact reading of CO2 inside the building. When a preset limit is reached the speed of the supply fan will increase automatically and it will push more fresh air into the building until the CO2 sensors give a reading less than this level, then the speed will decrease again," he adds.

Ensuring that water use is as efficient as the electrical and mechanical systems a sewage treatment plant has been included onsite. This processes all wastewater from the building for use in irrigation. "Not a single drop of water is wasted," assures Kanjoor.

Construction completed in November 2006 and the building is due to be officially inaugurated in Spring 2007. It is estimated that it will use 35% less energy and 40% less water than a conventional building.

Maximising solar power for lighting

The use of solar power to reduce the electrical load for lighting does not stop at maximising the use of daylight in the office. To reduce the demand on grid electricity, 50kW of electricity is being provided to the lighting system by a series of rooftop-mounted photovoltaic (pv) panels.

Covering the majority of the building's roof, the panels are grouped and connected to six intelligent inverters. "These check the [Dubai Electricity and Water Authority] DEWA power grade - what is the frequency, voltage and phase sequence - and it will generate the power [from the pv panels] in line with the DEWA power. That means you've got synchronisation," explains Kanjoor.

The system is connected in parallel to the DEWA electrical grid and operates purely in daylight hours, with grid power providing backup supply. The exact amount of power being provided and percentage of electrical power being supplied is still to be determined. Kanjoor explains: "That is still under testing, it is related to the intensity of the light and we have commissioned this in the peak winter. As per calculations we can reach up to 70% of lighting at peak load."

The amount of electrical power possible is purely limited by the roof space available for the panels. At night the full power for the lighting system is provided from the electrical grid.

Kanjoor explains: "We could store [electrical energy provided by the solar power for use at night] but that would need battery backup, which is bulky, costly and makes pollution. This is a green building, so we must limit pollution."

The fact that the building is primarily offices means there is little activity at night, with lighting required only in the 24/7 control rooms and corridors, so it is more cost-effective and energy efficient to use grid power during these hours.

The panels were installed by Dubai-based contractor Condor. Maintaining their efficiency requires a simple weekly wash, sandstorm dependent.

Heating up for cool air conditioning

At ground level, a second set of solar panels serves the air conditioning system for the building. Rather than electrical cells, these solar thermal panels comprise a series of copper tubes, through which water circulates. The system includes a total of 240 panels comprised of banks of five panels connected in series.

Around 300 gallons per minute of hot water is created in the system. It is pumped from here to an absorption chiller at the rear of the building. "This is the first time in the world that 90 Tonnes of air conditioning is being produduced using solar thermal energy," states Kanjoor. "We're using the hot water generated by the solar panels to serve the vapour absorption chiller. The water enters the chiller at 91°C and serves the building at 5.5°C."

There are four major parts to the chiller: the generator, condensor, evaporator and absorper. There is a vapour chamber with diluted solution of water and lithium bromide. When the hot water from the solar panels enters the chamber, the solution evaporates. The condensed water drops onto the heat transfer tubes of the evaporator, cooling the chilled water running through the tubes due to the effect of the latent heat of the vaporised refrigerant.

The solar panels have a capacity of 720kW thermal energy. A diesel-powered cogeneration plant provides the heating push-up when there is insufficient sunlight, however on the day of visit an outdoor temperature of 22°C was producing chiller inlet water at about 80°C.

 

Pacific Control Systems headquarters, Dubai

Client: Pacific Control Systems
Architect: Kersey Modi
MEP consultant: Orion Engineering Consultants
Main contractor: Condor Building Contracting
Lighting designer: Orion Engineering Consultants
MEP contractor: Condor Building Contracting

Suppliers

AHUs/fan coil units: MEKAR
BMS: Pacific Control Systems
Boilers: ECOFLAM/ MAIOR
Chillers: Carrier, LS Cables
Control valves: Honeywell
Cooling towers: DECSA
Fire alarm detection: Honeywell
Floor boxes: MK
IP backbone: Cisco Systems
LV switchgear: Siemens
Lighting control systems: Pacific Control Systems
Master system integrator: Pacific Control Systems
Photovoltaic system: Beck Energy
Security equipment: Honeywell
Standby generator: Perkins
Thermal solar panels: Enalter
UPS: APC
Voice & data equipment: Cisco Systems

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