The company Roots Up has come up with an innovative greenhouse solution, which can be used in arid, desert areas where rainwater is scarce. This is made possible by the fact that the primary source of water for collection in these greenhouses is dew. Their greenhouse is projected to be used in Gondar, Ethiopia, in an effort to help local farmers grow crops using low-tech solutions. What’s more, the water collected in this way can also be used as drinking water.
The Roots Up greenhouse can be constructed out of very basic materials and is very easy to build. Basically, the greenhouse is set into a pit dug in the ground while the greenhouse built around it is made of locally-sourced bamboo, ropes, a polycarbonate sheet, a bioplastic sheet and a cistern for water collection. The entire greenhouse can be built by unskilled laborers using only basic tools in about five days.
The greenhouse has a pyramid shape, and its walls are made by the polycarbonate sheet so it looks much like a tent, which can be opened at the top. The bioplastic sheet is used to create a funnel in the center of the greenhouse and works by directing the collected water into the cistern. This water is then used to irrigate the plants.
This design allows for the trapping of hot and humid air inside the greenhouse during the day. This air then circulates around the greenhouse rather than escaping back out. In the evening, when the external temperature drops, the top part of the greenhouse is opened, which causes drops of dew to form on the bio plastic sheet and trickle down run into the cistern. Rainwater can also be collected in the same way.
The amount of water that can be collected in this way depends on the level of humidity in the atmosphere. In an area with about 50% humidity like Gondar, it is estimated that about 44 gal (200 l) of water can be harvested a day.
Roots Up is currently raising funds for this low-tech project on Indiegogo. They hope to raise enough funds to start building the first greenhouses in Gondar in June, with the aim of building 10 more greenhouses by November.