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Fri 1 Jun 2007 12:00 AM

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Measuring resources

District cooling is now well established in the Middle East, but ensuring the continuous efficiency of the technology means monitoring the usage. How is the metering market changing to meet these needs?

The application of district cooling systems in the Middle East has soared in the past decade. The utility is now being applied almost as standard on most new large-scale developments in the region and the signs are that it is here for the long-term.

Specified primarily for its efficiency of operation compared to the use of traditional individual chiller systems, measures are now being taken to raise its potential further by engaging the final user. One way that this is being tackled is by the application of submetering systems.

"The bigger focus on energy efficiency is what drove the requirement for district cooling because on a large scale you end up saving a lot of energy," states Ayman Rashad, managing partner of systems integrator Acsys Control Systems. "The increased demand for district cooling and increased activity in this region is what's created the demand for the [sub] metering systems."

Many of the initial district cooling applications rely on bulk metering to determine the usage of chilled water. With this system, a single meter is connected to a building's mains supply and the overall consumption of the building is measured. On a building with multiple tenents, the costs are generally divided on a fixed-rate basis according to the floor space leased rather than actual consumption. There is therefore no incentive for users to be judicious about their consumption.

"A fundamental principle should be that payments for the utilities be based on measured use so there is an incentive to conserve utility resources and a consequence for wasting them," stresses BS Prashanth, business development manager with Palm District Cooling (PDC).

"People are buying properties in their own names...and consumers want their own bills. If you have a submeter then you are very cautious about what you consume; if it's a common meter then no-one cares - this is the driving force for change," adds Prashanth.

With submetering, separate meters are installed in each individual property, accurately measuring and recording the actual consumption of each area of the building. This data can then be used to allocate energy costs equitably.

"When tenants are being billed for cooling monthly they will get an idea of how much [air conditioning use] is costing them. They will raise their [room temperature] setpoints and will not keep their air conditioning on all the time...when you have a metering system the tenants will look at that and take care not to keep the temperature below comfort level, because every degree lower than necessary causes a lot of energy consumption down the line," adds Rashad. "Your chillers and pumps work more to achieve those temperatures; roughly one degree [of temperature difference] can end up costing approximately 10% more energy use, so metering is a good way of achieving awareness among users."

Meters are available in several formats, with the main types in use being mechanical and ultrasonic versions. In general submetering is carried out using ultrasonic meters, while electromagnetic meters are used for bulk metering. Each meter comprises three components: a flow meter; temperature sensors in both the supply and return pipes; and an integrator or calculator that records the energy consumed.

"The ultrasonic principle is that there are no moving parts, which makes it very durable and very accurate. A further feature of Kamstrup ultrasonic meters is the ability to communicate in different media by the same meter. We can provide the same meter with an interchangeable communications card, so if you want to go with a cabled system you will use a certain card and in the future you want a wireless system you can simply change card rather than having to change the whole meter," explains Rashad.

One of the main advances in metering has been the automatic meter reading (AMR) systems. The consumption data is collected from each meter by a communications bus onto a computer, then transmitted to the central control room for recording and billing purposes. Previously the transmission of data has been via fibre optic cables, however wireless communication systems have now been developed.

In the future, magnetic meters are expected to gain in popularity. "These have been used for large meters and manufacturers like Kamstrup have been developing them for small submeters as well. This will be the next step in metering I believe," states Fouad Younan, general manager of district cooling firm Emicool. Benefits of magnetic meters include the lack of mechanical parts and an increased accuracy, there is also no pressure change across the meter. "For district cooling applications these are perfect," stated Fouad. "They are being used for bulk metering and these may be preferred to ultrasonic versions in the future. The technology exists, but not for sub-meters, manufacturers are currently developing these," he explains.


But it is not only the final users for whom meters serve an important purpose; these are vital to the operation of the utility firms also. "Metering has always been an important issue: depending on how accurate the meter is and the system used, the more money you will make," stresses Younan. "It's mainly [district cooling firms] that are driving the changes. The efficiency of the meters is crucial to our revenues and profits at the end of the day - we don't want to over or under invoice customers.

Plus, if the room temperature is low the meter needs to be very efficient, so if the user lowers their air conditioning the meter needs to work accurately," he adds.

Submetering is becoming more popular on the region's new build developments and being retrofitted in existing buildings in some cases. PDC submetering projects include the 736-villa Jumeirah Islands project, several buildings in the Jumeirah Lake Towers development and all 4000 properties in Nakheel's Palm Jumeirah Shoreline Apartments.

The next step towards increasing and maintaining efficiency must be the introduction of regulations Rashad believes. "I think that eventually there will have to be some more regulations in terms of norms to govern the calibration of the meters," he states.

In Europe a percentage of the meters on every installation must be checked for operational accuracy every few years, with further checks required depending on the results. "The district cooling companies are already talking about consumer protection regulations, so users will know when they pay their bill that the meter reading is correct," Rashad concludes.

Wireless solution in Dubai Investment Park

At Dubai Investment Park (DIP) the use of metering systems has advanced significantly, with the installation of the first wireless system in the region.

The development includes several large projects that are owned and being built by differing parties. Emicool is providing district cooling to the properties on a bulk or submetering basis according to the individual clients needs. Acsys Control Systems is acting as the systems integrator for meter manufacterer Kamstrup on the project, designing, engineering and commissioning the system.

"Basically the concept is the same in that on every leased area there is a meter. The main advantage of this is metering the chilled water use via a wireless network, so it's a total automatic meter reading system," stresses Rashad.

Typically the central pc will be located in the central plantroom and the energy meters in the tenanted areas. "All data transmission between them is by wireless technology; up to a certain point data is transferred to an RF router then all data is transferred by a wireless RF signal back to the central building where it's relayed to a GSM router or concentrator, then by a GSM connection the data is transferred for billing," explains Rashad. The process removes the need for manual reading of the meters and is one of the highest levels of automation available in metering systems.

The system will be installed in phases, with some already in place. "Another advantage of this system is you can install and commission it in phases; one meter at a time can be installed, commissioned and connected to the system," explains Rashad. "With a wired system it is more complicated in terms of the network design, because in terms of the cables when you have an existing building it would be difficult to install any new cabling."

With the wireless system, there is no restriction on the distances the system can cover as additional routers and communications equipment can be simply added to cover the area. Installation is also faster and simpler as no conduit must be installed nor cables pulled or routed through the building fabric, making it easier for future changes also. "The client choose the solution because it's a lot more practical as the system grows to be able to collect the information without interference," explains Rashad.

Deliveries for the first phase of the system installation began in November 2006, with commissioning being undertaken only two weeks later.

"We have a few buildings on which we have tried the system," explains Younan. "This is the first wireless communications system tried on district cooling in the UAE. It worked perfectly well on these first buildings so we're going to proceed with using it on Green Community West, which has 600 villas and apartments and if it's successful we will implement it for the rest of our projects," he states.

"With existing systems we have faced problems with other contractors digging and cutting the wires, so we said why not go for wireless and avoid future problems," explains Younan.

The first installation covered the 12,000TR capacity system for Green Community One. The final system is expected to comprise a total of 50,000 meters on completion of the DIP development.

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