Nairobi House is a design for UN-Habitat that addresses the
unique concerns of crisis housing in a hot-humid climate. Notably, 60% of residents in Nairobi lack access to reliable sources of potable water. The 200-square-foot mircounit for four addresses this issue with a passive, water-harvesting “attic”. The attic is a simple device that utilises salt and solar energy to capture water from humid air, and can theoretically generate up to 8L of potable water per day.
Nairobi is an equatorial city, which means that solar and climate conditions are relatively consistent year-round. During the day, temperature is high and humidity is low. At night, temperate is low and humidity is near 100%. Nairobi house uses this diurnal swing (the climatic variation between day and night) as its primary design consideration.
Above is the prototype of a simple water device from a research paper titled: “Harvesting Water from Air: Using Anhydrous Salt with Sunlight”. This illustration shows how water can be captured by exposing moisture-saturated salt to solar irradiation. Nairobi house takes the concept of this device, and scales it up to 200sqft of salt beds.
At night, the attic space is left open so salt beds can be
saturated with moisture from the humid air. The attic is closed during the day,
creating a greenhouse effect that increases the temperature of the salt beds to
At this temperature, moisture evaporates and is collected for drinking. The
roof of the microunit can also collect rainwater.
The living space can be radically reconfigured between night and day through a pair of doors at each end. At night, when temperatures are low, the doors close to create a warm and secure space. During the day, when temperatures are high, the doors can swing open and facilitate comfort ventilation through the Bernoulli effect. This configuration can also benefit entrepreneurial microbusinesses.
Lastly, the house is built from modular bamboo composite
products that can be easily assembled or disassembled. The modernization of
bamboo, a native material in Kenya, not only provides a strong and eco-friendly
material for the house, but can also sustain local micro-industries.