Architectural Innovations for Desert Living
Rainwater Harvesting Concave Roofs For Arid Area Buildings
Iran is located in one of the most arid regions in the world, with approximately 84% of its land classified as arid or semi arid. Iran has an annual average precipitation of 252 millimeters, one third of the global average. Streams are seasonal, making fresh water almost unavailable around the year. However, what makes the problem of water shortage excruciating is the fact that almost 70% of the precipitation is lost to evaporation.
In a bid to find architectural design based solutions for this exacerbating problem, Tehran-based BMDesign Studios developed a Concave Roof System when planning a primary school in Iran's Kerman province. Taking into consideration the arid climate of its site in the city of Jiroft, the architects set about devising this unique roof system to offset the building's water consumption. The studio estimates its Concave Roof system could help the school collect up to 28 cubic meters of rainwater, which would contribute to its running.
The team believes this technique could be applied to other areas with similarly parched climates as a means to combating global warming through sustainable water sourcing. The water can in turn be filtered for drinking or integrated into interior gray-water systems. These systems also help reduce reliance on artificial air conditioning significantly. They could ultimately help keep people in their home regions who might otherwise have to move due to climactic changes.
The design addresses the problem of rapid evaporation with its peculiar bowl shape. The design is also capable of channeling even the smallest amounts of accumulated rain, coalescing them into drops big enough to harvest before they evaporate. These inverted shells also provide shade while allowing air to pass between upper and lower roofs, acting as a cooling system in the process. The inner shell itself is slightly domed such that only a section of the roof receives solar radiation directly at any time.
Reservoirs tied into the system are situated between building walls to take advantage of the thermal capacity of the water to regular interior temperatures.
The courtyard and circulation spaces are also sunken to further cool the complex. Temperatures are higher and precipitation in parts of Iran is as much as 2/3 lower compared to global averages, so every drop counts.