"We are still some way from going into production but the early results speak for themselves," says Patrick Jochum from the Technical University of Berlin's building technology and design department.
This new kind of greenhouse works almost like a perpetual motion machine. Water evaporated by the plants rises in the warm air up to the curved walls and is regained through condensation in a water-cooled shaft. A prototype greenhouse is full of green okra sprouts flourishing at 41 degrees Celsius
"In this way the amount of water needed by the water-saving greenhouse is reduced by another two-thirds," explains Jochum, who is working on the project with landscape architect Martin Buchholz and architect Michael Kraus.
"And coincidentally we produce organic vegetables almost by accident," says Jochum, since insecticides are unnecessary in the closed system. "The plants are extremely healthy."
The fertilizer with carbon dioxide is also reused with little loss.
The building is completely sealed off making it totally self-sufficient in water. Heat from the strong day sun is stored in water tanks meaning that the temperature can be maintained at the same level even during the cooler nighttime hours.
"We only need a small 300 watt pump to keep the circulation of the cool water going," Jochum says.
Further water saving measures are planned. Instead of using drinking water, the so-called 'grey water' from showers or washing machines can be used.
"The evaporation and the condensation work like a purification system," explains Jochum. Another level inserted above the plants means the evaporation element in the roof could even desalinate seawater.
The dream is almost within reach - a generation of greenhouses that create food and usable water in dry areas
"And in contrast to the desalination plants planned for the Almeria region, this technology works almost without using fossil fuels," say the scientists behind the project.
In a modified form this process could also be used in north or central Europe. In these circumstances the system would work on a seasonal cycle rather than a day-night rhythm.
Despite the greenhouse's resource saving features, the Berlin researchers have encountered economic problems in Spain.
"The price of water there is still unbeatably cheap - even when it trickles out of rotten pipes straight into the ground," Jochum argues.
But perhaps after the extreme drought this summer, the Spanish authorities will take a different view in future.