URBAN CASCADE - COOL ABU DHABI CHALLENGE
introduction Cascade
kas-ˈkÄ d
noun
1- A small waterfall, typically one of several that fall in stages down 2- A mass of something that falls or hangs in copious quantities. 3- A large number or amount of something occurring at the same time. 4- A succession of devices or stages in a process, each of which triggers or initiates the next.
CONCEPT
URBAN CASCADE - COOL ABU DHABI CHALLENGE
MAIN GUIDELINES It is of utmost importance for our current days and our future, to maximize our usage of available resources. To make structures and spaces that are at minimum self-sufficient in terms of energy, and at best, active producers of energy, instead of passive consumers. This is paramount when we have the possibility to rethink and design public space, twhich not only would be welcoming and pleasant to the public, but environmentally and economically responsible. The available resources in any public-space in Abu-Dhabi are Sunlight and high temperature-humid Air. Today, they raise Universal Thermal Climate Index of Abu-Dhabi’s public spaces to unlivable heat-stress levels, and thus, the key is to use these resources through scientific and creative strategies that are appropriate to Abu-Dhabi’s weather to transform any public space into an active zone. Effective cooling of public spaces can be achieved via a combination of strategies that work in a complimentary way providing opportunities that are approporiate for its local climate.
= T.E.G. Thermoelectric Generator
+6.15
=
Air temperature drop Up to -10 °C
o
-10
+ 2
-18
=
-18° H.A.C.
Hybrid Air Conditioning Technology
Dehumidified Air produced up to -18 °C less than environment + Potable water
T OWE R
Network
o
HOT HUMID AIR
Ca
-10° MISTING
High Pressure
Electricity generation to run water pumps and misting machines
WAT E R
CHILLED WATER
+
HEAT
POSITIVE ENERGY
CO O L I N G
+
AVAILABLE ENERGY
+0.00
Gr
SITE ANALYSIS
URBAN CASCADE - COOL ABU DHABI CHALLENGE
PATTERN DATUM Urban Heat Island mitigation meth-
SEATING / AIR CONDITIONING ELEMENTS
ods can be categorized into three major approaches : Cool Materials, Increased Greenery and Energy efficiency.
STRUCTURAL COLUMNS
Green vegetation forms the first natural barrier in the definition of a cooled urban space against the hot dry surroundings. The maintenance of a cool protected en-
CENTRAL COOLING FOUNTAIN
vironment requires water as the core and central urban element in space.
The site is developed with a simple hexagon grid as its primary space datum. This hexagon is the basic cell from which the repeating pattern is then developed. Arabic patterns were an inspiration for a complex tissue formed from a simple repeating element. Below, the repeated pattern can be seen, that generated for the ensemble of the project’s floor, canopy, and columns their aesthetic, structure, and general form.
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CONCEPT
URBAN CASCADE - COOL ABU DHABI CHALLENGE
EXPLODED DIAGRAM THERMOELECTRIC GENERATORS Using temperature difference between the surrounding air and the chilled water to generate electricity
SEMI TRANSPARENT ACRYLIC SHEETS Defuse light into the common space, allowing shadows’ variations
MAIN CANOPY STRUCTURE
Pattern shaped canopy of modular elements containing the running water for the misting system
TREE SHAPED SUPPORTING COLUMNS Growing out from the site’s grid and merging back with the canopy’s grid
SEATING ELEMENTS Air conditioning and public seating are combined to attract the public near fresh air
Tiled modular Public space The modular tiling gives flexibility in design between Concrete/Green/Water tiles.
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TEMPORARY SHADES CAN PREVENT UP TO 98% OF SOLAR RADIATION DIRECTING ONTO PEOPLE AND URBAN SURFACES FORT
AND
THROUGH
ENHANCE
OUTFOOR
DECREASED
THERMAL
RADIANT
COM-
TEMPERATURE
MATERIAL AND MODULAR DESIGN
URBAN CASCADE - COOL ABU DHABI CHALLENGE
ASSEMBLING PARTS The usage of light reflective materials as a passive factor in fighting UHI, the usage of High Albedo Concrete to create prefabricated modular elements is appropriate. Portlan cement mixed with water and light aggregate can increase solar reflectance to 40-70% and lower surface temperature day and night.
The CANOPY as well has one main 50cm beam module to form the whole pattern grid. This grid takes two types of joints whether linking between two beams or four.
0 0.5 0 0.5
m
m
0.50 m 0.50 m
Each element can be broken down to modular parts that can be easily fabricated and attached by joints to assemble the what seems to be complicated interlocking shapes.
The tree shaped COLUMN can be assembled from the roots growing out of the ground’s pattern, up to its main trunk that branches up to form the twigs that holds the canopy. This gives a total of 16 main pieces that form the main module that repeats in different rotations.
The GROUND’s tiling modules are composed of 4 possible shapes for each of the 3 functions: concrete tiles, vegetation tiles and water tiles. as shown in the soil details the finishing layers change to adapt with the needs of each site.
The FOUNTAIN SEATING element has 8 main pieces to form the growing roots that holds up the seating bench and then in the center rises the fountain surrounded with fresh air distributors.
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COOLING SYSTEMS
URBAN CASCADE - COOL ABU DHABI CHALLENGE
HYBRID AIR CONDITIONING SYSTEM A team of researchers from the National University of Singapore (NUS) has pioneered a new water-based air-conditioning system that cools air to as low as 18 degrees Celsius without the use of energy-intensive compressors and environmentally harmful chemical refrigerants. The system consumes about 40 per cent less electricity than current compressor-based air-conditioners used in homes and commercial buildings. This translates into more than 40 per cent reduction in carbon emissions. To add another feather to its eco-friendliness cap, the novel system generates potable drinking water while it cools ambient air. The novel air-conditioning system first uses an innovative membrane technology – a paper-like material – to remove moisture from humid outdoor air. The dehumidified air is then cooled via a dew-point cooling system that uses water as the cooling medium instead of harmful chemical refrigerants. Unlike vapor compression air-conditioners, the novel system does not release hot air to the environment. Instead, a cool air stream that is comparatively less humid than environmental humidity is discharged – negating the effect of microclimate. About 12 to 15 liters of potable drinking water can also be harvested after operating the air-conditioning system for a day.
Canopy Level
o
CO O L I N G
-18
WAT E R
T OWE R
+6.15
+0.00
Ground Level
Resources: A Hybrid Air Conditioning System Employing Membrane Dehumidification and Dew Point Cooling by the Department of Mechanical Engineering National University of Singapore
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COOLING SYSTEMS
URBAN CASCADE - COOL ABU DHABI CHALLENGE
MISTING and EVAPORATIVE COOLING Evaporative spray cooling systems provide thermal relief on hot days, even in a subtropical climate. Misting fans produce a cloud of very fine water droplets through forced mixing between the air stream and water. Within the canopy’s structure, chilled water runs inside the beams through pipes and then with the aide of high pressure nozzle, mist is released to freshen the shaded area. This process can be explained as when water molecules evaporate into the air, the water changes from a liquid to a gas state. A certain amount of energy or heat is needed to assist this process of changing water from a liquid to a gas, which is automatically drawn from the surrounding air – thus, evaporation lowering the ambient temperature around the misted area. While this process is most efficient in dry atmospheres, it works strongly with the previous strategy that dehumidifies and reduces the air’s temperature. Transforming the air under the canopy into a cool and fresh atmosphere. Depending on the weather conditions an air temperature reduction of 5-15o C may occur in the immediate area around the misting nozzzles
+6.15
Canopy Level
CO O L I N G
WAT E R
T OWE R
o
-10
Resources: GUIDE TO URBAN COOLING STRATEGIES - Paul Osmond and Ehsan Sharifi - July 2017
+0.00
Ground Level
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ENERGY PRODUCTION
URBAN CASCADE - COOL ABU DHABI CHALLENGE
THERMO-ELECTRIC GENERATORS A thermoelectric generator (TEG), also called a Seebeck generator, is a solid
able. Adding to that, experimental research
state device that converts heat flux (temperature differences) directly into
has shown that power generated from unit
electrical energy through a phenomenon called the Seebeck effect (a form
surface with thermoelectric panel is 30
of thermoelectric effect). A small (4cm x 4cm) TEG module for example uses
times greater than the power generated by
the temperature difference between its two sides to generate electricity.
photovoltaic panel.
This would allow us to use the heat that is present in the air in Abu-Dhabi’s
TE panels have no moving parts, their struc-
public space as a small source of energy and electricity.
ture is simple, they require no maintenance,
And considering that chilled water already runs through the canopy for the
they are long lasting, and they allow tem-
misting network, therefore the high temperature difference is achieved be-
perature control, directly convert the elec-
tween the heated air on the canopy external surface and the low tempera-
trical energy and work quietly.
ture of the water inside
0.15 m
Possible addition of Concentrating Optics
0.05 m
Glass vacum enclosure
the
while, Photovoltaic solar pales converts pho-
Water distribution pipe
tonic energy from sun to electricity and requires direct sunlight
High-Pressure Misting water nozzle
0.10 m
to achieve that and thus is not always availResources: THE THERMOELECTRIC SOLAR PANELS - R. AHISKA, L.I. NYKYRUY, G. OMER, G.D. MATEIK
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Canopy L
T OWE R
directly to electricity;
+6.15
COLD side
WAT E R
Cold water canal for module cooling
CO O L I N G
heat generated by sun
0.05 m
converts
0.10 m
panels
solar
0.30 m
Thermoelectric
Solar absorber (HOT side)
Thermo-Electric Generator module
+0.00
Ground L
URBAN CASCADE - COOL ABU DHABI CHALLENGE And while the efficiency of Thermoelectric generators increases with the increase of the temperature difference between the Hot and the Cold side, the delta in the case of the project is not at it’s highest, but it is enough however to create an electric current during the day to provide light, charge telephones and assist in pumping water through the structure
SEMI-TRANSPARENT ACRYLIC PANELS
PANEL-SUPPORT
THERMO-ELECTRIC GENERATORS
STRUCTURE BEAMS
MISTING NOZZELS
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POSSIBLE VARIATIONS ADAPTIVE MODULES The flexibility that modular design offers is that it can be easily applied across multiple scales with different variations regarding the attribution of public elements. The unifying grid makes all elements of the elements attachable and inter lockable in very different ways, and yet independent in and of themselves to fight urban heat islands The formula that generates this design is adaptive to all variables from site shape, need of vegetation, need of water elements, spread of misting nozzles and the spread of shading panels. The design can always be responsive to the needs of its context by the fact that it can be modified in place, in anytime by adding the needed elements, or replacing some of the existent modules.. The examples shown to the right vary in surface between 150 m2 / 400m2 / 1000m2. Below the generative script used to make adaptive variations to any proposed site.
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URBAN CASCADE - COOL ABU DHABI CHALLENGE