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“Luanda is by far the largest city in the world in which fog farming is practicable. Though Luanda experiences something of a rainy season between March and April, for most of the year precipitation is nearly absent — averaging 0 millimeters/month from June to August — as the Benguela and Angola currents of the Atlantic Ocean combine to prevent the humid air from condensing into rain. This combination of humidity, aridity, and explosive population growth creates a situation uniquely suited to an experiment in urban fog farming”
www.betamammoth.wordpress.com
Based on the experiences of betamammoth, we aim to integrate this quite amazing technique of water harvesting from air into our urban approach. Relying on these numbers, we see the potential of replacing all water truck driving to the musseques with water harvested on site.
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INTERVENTION
Average Temp ( C)Average Sunlight Hours/DayAverage Wind Speed (Beaufort)
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/Win
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Relative Humidity (%)Rainfall (cm)
Relative H
umidity
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Luanda, Angola Climate Graph (Altitude: 74m)
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DecNovOctSepAugJulJunMayAprMarFebJan
Luanda, Angola Climate Graph (Altitude: 74m)
Fog collection works not by condensation, which is what happens when water vapor hits a cold surface and transforms into a liquid. In fact, the water in fog is already in liquid form—it’s just in very, very small drops. As wind blows the humid air through the harvesting net, tiny droplets stick to the coarse woven mesh, made of a kind of plastic netting that is designed to shade young fruit trees. As more and more tiny droplets stick to the net, they clump together and form drops, and eventually gravity pulls the drops down into a gutter. From there, the water flows through tubes towards where the water is captured.
Luanda
Cabinda
Malanje
HuamboBenguela
ANGOLA CURRENT
ANGOLA DOME
BENGUELA COASTAL CURRENT
ANGOLA BENGUELA FRONT
SOUTH EQUATORIAL COUNTER CURRENT
SOUTH EQUATORIAL CURRENT
EQUATORIAL UNDERCURRENT
Lubango
HARVESTING WATER FROM THE HUMID AIR
The humid air from the Atlantic Ocean pulls into Angola’s shoreline as an almost constant drift from the south-east. As the humid air do not turn into rainfall in the dry season, the relative humidity in the air is especially high. In the dry season, the relative humidity is about 80%.
Humidity harvesting nets is a well known technique, used in small-scale at several different places on earth. In the Sahara desert, people have been using simple textiles to harvest water from the air, while woven plastic nets has been used in several projects lately.
This water harvesting seems to work extremely efficiently in small-scale projects -why not extend it to an urban scale?
13 liters/ m2/ day1m2 =
Two workers in Bellavista, Peru, perched 18 feet (5.5 meters) high to sew nets onto a fog-collecting apparatus in October 2007. Conservationists Kai Tiedemann and Anne Lummerich designed this fog catcher--nicknamed “Eiffel” for its metal frame--to collect up to
660 gallons (2,500 liters) of water a day in the foggy winter months from June to November.
When the fog-water starts flowing, “it’s amazing,” Lummerich said.
“It’s like opening a tap.”Bringing the Natural Water Cycle Back
Suitable plastic mesh could be produced locally on rolls
HOW TO DENSIFY THE INFORMAL AREAS WITHOUT OVERRIDING THE INFORMALITY?
“When you no longer improve your house, you are close to death”
ARAB PROVERB
VIANA IS FULL OF EMPTY OR HALF-BUILT STRUCTURES WAITING FOR THE POSSIBILITY TO GROW...
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IN H
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The moist catchers need to be elevated over the expected densification hight, in order to catch the air drifting from the Atlantlic sea
The nets will need a massive structure to handle the pressure from the wind.
Each m2 should take the pressure of 50 kg, meaning 5 tons on 100 m2.
1 2
What if the structure in itself could make a base for vertical densification of Viana? The structure would be an integrated part of the urban architecture, providing a grid of vertical plots for people to build in to.
The structure will allow for an informally built structure in a grid system providing vertical lots.
3 4
INTERVENTION
ABOUT BUILDING BY YOURSELF / step-by-step
THE WAY PEOPLE BUILD
Finding a free plot. Clearing it.Trees are highly respected, and usually kept, often as shadow space in the centre of the courtyard.
Build the main house, occupy by marking the edges with fences. Extending, fixing, repairing, improving...
“The principal error of the Government is to not recognize the fact that people can do! You see people are building everywhere, they are capable of building their houses.”
MAURICIO, Architect and Teacher in Architecture, Lusiada University in Luanda (ULA)
“Where dwellers are in control, their homes are better and cheaper than those built through government programs or large corporations”JOHN TURNER Brazillian Architect and Urban Planner
In Viana, most houses are built with a reinforced concrete frame, filled in by adobe bricks. Roofs are usually made with corrigated steel plates. Walking in Viana, empty frames and unfinished structures are as usual as finished ones. It is clear that the state of building is a continous one, where materials are bought when you have a small profit, and that adding on and repairing is a constant process of life.
It is obvious that the materials of the houses are chosen by what’s available and cheap. The heavy construction is good for thermal mass qualities, but the thin steel roofs heat up the small houses.
Fill-in concrete frames is the base of self-building in Viana
POSSIBLE DENSIFICATION IN STEPS PROVIDING PUBLIC SPACE
Existing structure Added structure Connecting to structure/house improvement
Possible densifying Existing structure First build, then move
SHADOW AS QUALITYTHE SOIL FLOORTHE CENTRAL TREEHOUSES FACING THE SHARED COURTYARD
DENSIFICATION GRIDS/ Courtyard Logic
The musseques are characterized by one-storey houses densly built in connection to a variation of courtyards. The creation of the court is decided by the original pattern of trees, on which the houses are built around. The courtyard is the semi-private zone between the houses and the street, often halfly opening towards it.
In our densification strategy we use the clear courtyards as base for vertical densification, letting the grid cores preferaby connect to these, instead of directly towards the street.
10 m
10 m
DENSIFICATION GRIDS
STREET
black water treatment
humidity harvesting
sanitation core
gray
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DENSIFICATION GRID10x10mWood (local module production, Viana)Light add-on structure
WATER COREConcrete/ bricks (built on site)Rough structure handelling the flow of people and the treatment of water
WATER CYCLE
MOVEMENT FLOW
FLOW CORE
Another add-on structure/ADDING IN HEIGHT
VERTICAL WATER CORE AS SOCIAL ARENA
1. 3.2. 4.
WAT
ER IN
HUMID
AIR
HUMIDITY
HARV
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GRA
Y WAT
ER C
APTURIN
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APTURIN
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TOILE
T FL
USH W
ATER
TOILE
T FL
USH W
ATER
WASH
ING H
ANDS
WASH
ING H
ANDS
MASS TA
NK
HUMIDITY
HARV
ESTIN
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BLACK W
ATER
Con
trol
pip
es
Vert
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was
te w
ater
gar
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Black water ventilation shaft
Hum
idity
har
vest
ing
faca
de
Sani
taty
sha
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BLACK WATER GRAY WATERcourtyard/ entrance zoneHUMIDITY
HARVESTING
BLACK W
ATER
FILT
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G CEL
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graywater runoff towards street
bigger stones etc in the first meter
black water filtering biotope(banana plant)5
m
a m
ore
publ
ic h
ight
allo
win
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ared
ac
tiviti
es, r
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ove
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istin
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3,2
m3,
2 m
take out fertilizer
CORE WATER FLOW
The core is a standard heavy concrete construction serving water and sanitation on site for the inhabitants of the grid. It’s concidered a rough zone where daily routines, water handelling, cooking, growing etc can happen within a frame of shared water resource. The core is also the flow area with vertical connection (stairs).
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