Clever Concave Roof Design Harvests Rainwater in Hot Climates

We know that water is life, and the growing scarcity of water in many regions around the world is already affecting food security, and could very well prompt future climate migration and conflicts over water.

All these factors are compelling reasons to create self-sustaining buildings that are appropriately designed for their local climate and possibly even support local biodiversity. ArchDaily shows this interesting rainwater-collecting design from Iranian firm BMDesign Studios, which features a double-roof design with a bowl-shaped component that augments the amount of rainwater that can be collected in arid climates.

© BMDesign StudiosThe architects note that the design is adapted to the low levels of precipitation in this region, which is one-third of that of the world average; rain here evaporates at three times higher than the world average as well. Thus, the concave roof is made to "help [make] even the smallest quantities of rain [flow down] the roof and eventually coalesce into bigger drops, just right for harvesting before they evaporate”.

In addition, the other roof upon which the concave roof sits is slightly domed, so that during the bright daylight hours, only part of the roof is exposed to sun and airflow between the two roofs is increased, to keep the interior cooler. The bowled roof also provides extra shading.

© BMDesign Studios

© BMDesign Studios

© BMDesign Studios

For a prototype of a school building with 923 square metres (9,935 square feet) of concave roof, it is estimated that 28 cubic metres (7,396 gallons) of water would be collected -- the architects say that's about a 60 percent rate of efficiency and still, nothing to sneeze at.

© BMDesign Studios

Water will be stored in reservoirs that will be hidden between the walls of the buildings, and can help to passively cool the interiors, thus “[lowering] the overall carbon footprint of much-needed air conditioning in this harsh environment.” The overall site design also includes a series of "wind towers" that will funnel in fresh air into the buildings -- obviously inspired by traditional "windcatchers" found in Persian architecture.

© BMDesign Studios

© BMDesign Studios

The architects are now working to refine their design to increase the efficiency of water harvesting. Not much information on the materials that will be used, but solutions like these are yet another fitting example of adapting new aesthetics to traditional ideas of how to keep cool and conserve water, of forging an architecture that's appropriate for the local climates and perhaps also makes use of tradition building techniques. While it's nice to build shiny new things, often there's a lot of wisdom in traditions. More over at BMDesign Studios.