Continuing our special focus on reducing utility use in existing buildings, MEP Middle East reports from the Grand Hyatt Dubai on its moves to a sustainable future.
Recent reports have criticised the Middle East's hotel industry for its high power and water consumption, however there are some that deserve praise for exactly the opposite. One such example is the Grand Hyatt Dubai, which has recently made moves towards more sustainable operation that should make the international as well as the local market sit up and take notice.
In a bid to increase the sustainability of the building and reduce the overall energy use and running costs, a thermal solar system has been installed to serve the building's hot water system. Further adaptations of the MEP system have resulted in a 3.636 million litre (800,000 gallon) weekly reduction of potable water consumption and more changes are planned to ensure the optimisation of both energy and water use at the site. But what has prompted these moves and how do you make a five-star hotel operate more sustainably without reducing the guests' experience?
The 674-room Grand Hyatt Dubai is located close to the city's creek and includes a state-of-the-art convention centre and a spa in addition to the hotel facilities plus 14 restaurants and bars. It is owned and operated by Hyatt International, which is currently undertaking a worldwide initiative to increase energy conservation in its properties. "Hyatt as a company is looking at a global initiative to reduce energy consumption, so [the individual hotels are] asked to look at all new technologies and different ways of doing the standard things," stresses Philip Barnett, Grand Hyatt Dubai property manager.
In response to this initiative, the latest system to be adapted by the Grand Hyatt Dubai is that of a thermal solar system. Fully operational since October, this is providing hot water for the hotel's guest rooms, dehumidification system, laundry, kitchens plus all of its spa and swimming pool facilities.
The system comprises an array of evacuated tube solar collectors that are filled with a liquid that boils at 130Ãƒâ€šÃ‚Â°C. The collectors installed have a total surface area of 1,800m2 and are sited on the roof of the adjacent Grand Cineplex cinema. This location was chosen for two main reasons: the hotel has a large amount of mechanical plant on its own roof, so space was more limited; plus, the area used is exposed to uninterrupted sunshine. The hotel's architecture provided certain restrictions in this aspect, as Barnett explains: "The high tower casts a shadow on the intermediate tower at certain times of the day, and even though this system generates heat in the shade it doesn't generate as much [as when in direct sunshine]."
As the cinema is part of the overall complex there were no contractual negotiations needed to use the space. Barnett stresses however that had the cinema roof not been available, the flexibility of the system chosen means that an alternative solution could have been found by making use of the hotel's various roof spaces. "The only thing about solar systems is you need the space to install them. This particular system could be broken up into modules and still work...I could have located some panels on different roofs, and as long as they could be connected together it would work," he assures. "The shape of the building doesn't restrict you from using a system like this, it just needs to be engineered a bit better."
The system is operated as a continuously flowing primary circuit. As the liquid is heated it is circulated to storage tanks before passing through a heat exchanger to indirectly heat the building's hot water supply. "The plant supplies the hotel's hot water requirements during the day, then there is also enough superheated liquid stored in the tanks for the needs at night, so it's cut down our boiler use tremendously," states Barnett. "We will be able to generate, depending on the time of year, 800-1,200kWh of energy [from the solar system], which is sufficient to heat the hot water that we require to run this building...even at this time of year we're satisfying 90% of our needs," he adds.
The reason for choosing a solution with a higher boiling temperature is due to the high temperature of water needed in the facility. "We run the building's hot water system at 80Ãƒâ€šÃ‚Â°C because we've got industrial laundries, it's not just tap water we're supplying," explains Barnett. The water is heated to above 100Ãƒâ€šÃ‚Â°C in the panels before being stored in the tanks.
The primary aim of the solar system was to reduce the use of the existing diesel-fired boiler system, cutting the hotel's fuel consumption and CO2 emissions. Three 1,200kW diesel-fired boilers were included in the original hot water system, with one in constant operation and the others coming on line as needed to meet demands. The design intent of the solar system was to replace one of the boilers, a result which is already close to being met, with further expansion of the system possible.
The panels have been interconnected with future maintenance procedures considered. The overall system includes variable frequency drive operated pumps, expansion vessels, special water treatment equipment, safety valves, plate heat exchangers, motorised valves, plus a 3km pipe network.
The panels are filled with a liquid that has a boiling point of 130Ãƒâ€šÃ‚Â°C enabling water temperatures of up to 100Ãƒâ€šÃ‚Â°C to be achieved; currently an average of 80Ãƒâ€šÃ‚Â°C is being produced on daily basis to generate energy equivalent to 800-1,200kWh.
The system can be remotely controlled by GSM Modem, which enables access to real-time data based on various sensors positioned throughout the network. Pump and motorised valve positions can be checked remotely as can the solar radiation levels. The installed system can be further expanded to accommodate future increased loads.
The water coming from the solar system is now the primary source of heating for the hotel's hot water supply. Barnett explains: "There is a [hot water supply] ring going into the main building and back to the boiler, what we did is put the solar system heat exchanger in front of the boilers so that's the first thing that heats the water. If the temperature is not high enough and the boiler is still required it will come on automatically."
The fuel savings have been immediate and impressive, with a 40,905 litre (9,000 gallon) reduction in diesel fuel consumption during October. The rising cost of diesel means that the financial benefits the solar system will bring the hotel are also increasing. It also contributed to a lower payback period for the system, enabling its actual installation.
Barnett explains: "About three years ago I got some initial quotations and at that time it looked like a future project that was expensive and would be difficult to get accepted [by the hotel management]. Then the fuel price doubled over the past two years and it keeps going up while the cost of the solar equipment is coming down, so those two factors together mean that payback is now around three to four years - initially it was double that," he stresses.
In addition to more efficiently heating its water supplies, methods have been implemented at the Grand Hyatt Dubai to significantly reduce the hotel's actual water consumption. One of the main factors here is the use of treated sewage effluent in the cooling towers.
Following negotiations with Dubai Municipality, the hotel is being supplied with treated sewage effluent directly from a ring main that supplies irrigation to the city's gardens. "[Dubai Municipality installed a metered line to the ring main] we then installed a treatment plant that takes this effluent water and purifies it to a satisfactory level that can be used in the cooling towers," explains Barnett.
Around 0.55 million litres/day (120,000 gallons/day) are passed through a series of filters, with a proportion then being treated in a reverse osmosis (RO) plant to produce pure water. This pure water is then blended with the filtered water to obtain the same TDS level as Dubai's potable water supplies prior to being used in the cooling towers.The system has reduced the potable water consumption at the hotel by around 3.636 million litres (800,000 gallons) per week.
In addition to reducing demands on potable water supplies, again financial benefits have been achieved by using this system. "It's not only environmental benefits [that can be achieved], you also get commercial benefits as a business. The sewage effluent is very high in phosphates and nitrates, but it's also a lot cheaper than [mains potable] water," stresses Barnett. "The DEWA rate for [potable] water is now 35 fils/gallon; taking into consideration the waste from the treatment plant, we're paying about 10 fils/gallon, so I'm getting a 25 fils/gallon saving and water is expected to go up in price," he adds. The water treatment plant will have a payback period of around one year based on current prices.
The hotel is now looking at other options to further reduce its water use, including capturing grey water - a process that will be simplified due to the inclusion of a two-pipe system during the construction phase. Options for using grey water include irrigation and make-up for the hotel's water features. A further process being considered is the recycling of laundry water where the water from the final rinse cycle is filtered and reused for the first wash.
"Our goal as a hotel is to reduce our utility consumption by 20% by 2008. That's very ambitious, but as a corporation Hyatt has set that as our target worldwide," stresses Barnett. To date 5% savings have been achieved and in October the hotel was accredited to ISO 14,001 certification. In addition to the more unusual methods used by the hotel, areas tackled include the fine-tuning of the building management system to optimise temperatures hence energy use, plus the use of water restrictors on the kitchen taps.
Clearly serious about their commitments to the local as well as global environment, Barnett is a founder of the Emirates Green Building Council and believes that those who own or manage existing building stock must now play their part in the region's sustainability drive. "Right now they are focusing on new buildings, but eventually they will focus on older ones as well. There is a LEED (Leadership in Energy and Environmental Design) list of things that you should have and we are trying to apply these to an old building as well. It's a bit more difficult in areas but we'll do our best," he stresses. Emirates Green Building Council chair Dr Sadek Owainati adds: "The achievements made at the Grand Hyatt Dubai have exemplified that opportunities exist to transform existing buildings to attain a better level of sustainability."
Main contractor: Cheqpoint Tech Trading LLC
M&E consulting engineer: Mr Suneil Deliwal of M/s. Cheqpoint Tech Trading LLC
Mechanical and plumbing contractor: Birmingham Metal Industries
Construction start date: 1 May 2007
Completion date: 15 September 2007
All plant supplied by Cheqpoint Tech Trading
Project: Approx US $0.95 million (AED3.5 million)