In hot, dry areas of the world, collecting enough rainwater to grow crops can be difficult. Another potential source of water for collection, however, can be dew. Roots Up has designed a greenhouse to collect dew in Gondar, Ethiopia, as part of a scheme to help local farmers with low-tech solutions.
The water collected is, of course, meant for watering the crops contained within the greenhouse. It can, however, be used as drinking water if needed. Like the Warka Water bamboo tower, the Roots Up greenhouse uses basic materials and simple to build.
The greenhouse is set into a pit dug into the ground and is built using locally-sourced bamboo, a polycarbonate sheet, a bioplastic sheet, ropes and a cistern water tank. It can be constructed by unskilled people with just basic tools and takes around five days to complete.
The polycarbonate sheet forms the pyramidal walls of the greenhouse, like a tent, and can be opened at the top. The bioplastic sheet is set up as a funnel in the center of the greenhouse and directs water into a tank. Water from the tank is then used to irrigate the crops.
The greenhouse works by trapping hot, humid air during the day and ensuring that it circulates rather than being lost. When the outside temperature drops in the evening, the top section of the greenhouse is opened, allowing dew to form on the the bioplastic sheet and run down into the water tank. This setup also allows for the collection of any rainwater.
According to Roots Up, the amount of water that can be collected varies depending on the level of humidity in the atmosphere. It says that in the high region of Gondar the humidity is around 50 percent in the dry season and estimates that up to 200 l (44 gal) of water a day can be harvested.
Roots Up is raising funds for its low-tech project with a flexible funding campaign on Indiegogo. The organization is aiming for the first prototype of the greenhouse to be built in June, after which it intends to roll-out its low-tech solutions in Gondar. Training will be delivered from September with an aim of 10 further greenhouses to be built by November.
The video below provides an explanation about how the greenhouse works.