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|25 Feb 2012|
Behind the scenes at Masdar City.
Billed as one of the most sustainable cities in the world, construction of the 6km2 Masdar City began in 2008. One of the five integrated units under the Masdar umbrella, backed by Mubadala, Masdar City is an emerging global clean-technology cluster where current and future renewable energy and clean technologies are showcased, marketed, researched and developed. With the potential to house up to 40,000 residents and 50,000 commuters when fully built in 2025, Masdar City will also be home to the International Renewable Energy Agency (IRENA) and the Masdar Institute of Science & Technology (MIST). The anticipated cost of the entire development is $18bn to $19bn.
Every aspect of the city’s urban planning and architecture has been approached with sustainability in mind, with a substantial focus on natural cooling in the way the city has been engineered. Streets are built to be optimally oriented on a southeast-northwest axis, thereby providing some shading at street level throughout the day. “We have done extensive wind engineering into thermal comfort,” explains Gaurish Wagle, urban planning professional.
Unlike normal city parks which are built as recreational areas only, Masdar City’s linear parks are scientifically placed so as to channel prevailing winds into the city, 38░ counterclockwise of the north axis. Located throughout the city, they are intended to provide convenient, shaded oases for residents, workers and visitors, incorporating walking, jogging and bicycle trails, benches and other recreational facilities. “It is the principle of wind movement from a wider space to a narrower space. It gets flushed, making it cooler and healthier. There is a constant flushing of fresh air,” says Wagle.
The materials used for the building fašades are designed for cooling purposes. Laboratory buildings are shielded with ETFE (ethylene tetrafluoroethylene) cushions that ensure almost no solar gain on the structures, as well as limiting the heat radiated on to the street. Windows not already shaded by adjacent buildings have louvres set to prevent direct sunlight from entering the building.
“Transportation is one factor and building efficiency another that is being constantly improved by providing adequate materials that minimise solar gain,” says Wagle. “GRC (glass reinforced concrete) panels form a cushion and reduce heat gain within the building envelope. It is a screen which shades the glass and acts as a buffer that reduces the heat gain on the wall so the building inside remains cool.”
Excluding the windows, the rest of the fašade is wrapped in 90% recycled aluminium sheeting which has 6.7kg of embedded carbon per square metre of 2mm-thick sheeting, compared to conventional aluminium sheeting, which has 56kg of embedded carbon per square metre. A wind tower which rises 45m above the podium is a landmark of the MIST neighbourhood. Its height allows the capture of upper-level winds, which can then be directed to the square at its base. In addition, the square acts as a recreational space, housing cafes and restaurants which spill out on to it.
“When the temperature hits a certain level, the wind louvres open, suck in the air, and direct it down the tower. The temperature in the courtyard gets a bit cooler and more comfortable,” explains Wagle. While cooling is a significant focal point of Masdar City, the sun has played a huge role in its development. Masdar’s 10MW solar-power plant is the largest grid-connected plant of its kind in the Middle East. Constructed in 2009 at a cost of $50m, the 22ha plant comprises 87,777 polycrystalline and thin-film modules which work to provide clean energy to the MIST campus within the city, as well as Masdar’s temporary on-site offices, as well as some of the ongoing Masdar City construction activities.
“Overall the plant is energy-positive. Over a certain period, we are producing more here than Masdar City consumes. It is not always the case – at night, there is no power production, but ordinarily there is more production than the site consumes,” says Dr. Afshin Afshari, professor of practice and programme lead engineering systems and management. Excess is then transferred to the grid, but the plant is yet to provide a visible return.
“When we built this plant, the idea was that Abu Dhabi would introduce a feed-in tariff and, like many countries in Europe, we would get paid at a price higher than the going rate for electricity. This has not yet been introduced, so the power we are feeding into the grid is not being rewarded at even the retail price of electricity. We are hoping that, in the near future, there will be a feed-in tariff and then we can calculate the payback time,” says Afshari.
In addition to the 10MW solar-power plant, there is a 1MW rooftop installation at MIST and a smaller installation near the site offices. Outside of Masdar City is the Shams 1 plant, which is almost 80% complete and due to go into operation later this year. A concentrated PV test field is also currently under construction.
And while the cost of silicon crystalline for PV continues to decrease, future solar farms are expected to be constructed at a lower cost, particularly Noor 1, the 100MW PV power plant that is currently in its tender stages.
Cleaning of the panels represents a significant cost, and Masdar is looking into testing various cleaning options that minimise water use. At present, the panels are cleaned manually using dry brushes.
Another technology employed, though this is still in research and development, is the beam down or concentrated solar plant, which has the potential to convert sunlight into electricity in a more efficient and cost-effective way than the other technologies. Initial results suggest that the 100kW tower could generate 75MWh to 85MWh of clean electricity a year, enough to power ten to 15 homes.
At Masdar City, sunlight is also used for the primary purpose of illumination. A Solatube passive daylighting system is employed, which can transfer sunlight for up to 15m while blocking UV rays. Daylight capturing dome lenses and in-dome reflectors redirect low-angle sunlight and reject strong midday sunlight to provide consistent lighting through the day. By measuring light intensity in the room, the system can also detect whether it needs to use the integrated electric light kit to provide additional illumination in low daylight and night conditions.
Waste is taken equally seriously at Masdar City, which has strived to minimise waste during the construction process. The city has achieved this by seeking to reuse and recycle all waste steel, concrete and timber generated during building. “Up to 96% of construction waste is being diverted from landfill and recycled in the building of the city,” says Wagle. “All the construction waste is stocked on-site and recycled, as is the sweet sand, which is then re-used.”
Almost all Masdar City’s construction waste is brought to the 12ha on-site Material Recycling Centre (MRC) for separation and processing. Wood is segregated and stockpiled for reuse in building the city, or for processing in a wood chipper. Concrete waste is ground down using a crusher for reuse in construction and particularly for infill. Steel and other metals and plastics are collected and sent off-site for recycling. Other materials such as gypsum board and damaged glass-reinforced concrete panels are all being tested for recyclability. Waste that cannot be recycled may be used as fuel in a future waste-to-energy plant.
Some waste wood has been turned into mulch wood for use in landscaping around the Masdar offices and in other developments in the UAE. The landscaping also targets a 60% reduction in water usage per square metre through a number of strategies including micro-irrigation, landscaping design that minimises plant evapo-transpiration, as well as low-water-use and the planting of indigenous plants and trees. For irrigation purposes, 100% treated wastewater is used, while water features are shaded to reduce evaporation.
“Masdar contributes to the Abu Dhabi Economic Vision 2030 sustainable urban planning goal through its development of projects adopting sustainable design and criteria,” says Alan Frost, director, Masdar City. “Masdar has developed sustainable guidelines for facility management (FM) and maintenance operations, which enforce sustainability KPIs among FM service providers to ensure sustainability throughout Masdar City.”
High-profile science experiments mean the facility has to be maintained at the optimum standard. Upon entering certain areas, including the electron microscopy room, a sticky pad on the floor ensures dust is picked up from the bottom of entrants’ shoes. The flux of air into the nanofabrication clean room is limited through a thick vinyl sheeting. Dr. Marcus Dahlem, assistant professor: microsystems engineering, says: “The number of particles of specific sizes is very limited, so it is [necessary to provide] a clean environment.
“When fabricating these small structures, most of them are much smaller than your average dust particle, so if you get a big dust particle on top of your structure, it could destroy the whole thing,” says Dr. Dahlem.
Source: Arabian Business.com