Tehran-based architecture studio unveil proposal for a roof system which harvests water

Bowl Shaped Roofs Collect Rainwater in Iran


Published in Climate Action & WDCD by

As the planet continues to warm, water scarcity threatens some 30 to 40% of the world’s population. To address their home country’s arid climate, Tehran-based BM Design Studios has unveiled the Concave Roof, a double-roof system which acts as both rainwater catchment and a natural cooling mechanism.

The idea was first proposed in the plans for a primary school in a specially hot and dry area of Iran. The intention was to offset the building’s water consumption by collecting and harvesting the little amount of rain that falls in the region.

“A concave roof like this will help make even the smallest quantities of rain flow off the roof and eventually coalesce into bigger drops just right for harvesting before they evaporate,” said the architects.

The domes also provide additional shading and allows air to move freely between them, cooling the entire building. At a school with 923 square meters of concave roof area, it is expected that 28 cubic meters of water could be collected, with an efficiency of about 60 percent.


Projects like these help us to imagine ways of combatting global warming through sustainable water sourcing. The team believes the technique could be applied to buildings in any similarly dry climate.

“Some 65 per cent of Iran has an arid or hyper arid climate,” they explained. “Unfortunately, every year, this zone expands. Big lakes like Lake Urmia have shrunk to a fraction of their size, gradually disappearing. The consequences include thousands of farmers losing their jobs and [pushing] the city itself to the brink of rationing drinking water. We may not be very far from witnessing a big displacement of people.”


Indeed, most of the consequences of climate change are related to water. Rising temperatures mean that many people are now threatened by too much water — rising seas, record-breaking rainfall, and flash floods — while others are threatened by too little, in the form of drought. By 2025, 1.8 billion people will experience absolute water scarcity, and two-thirds of the world will be living under water-stressed conditions. Accordingly, water is one of the 5 main topics set forth in the briefing of our newly-launched WDCD Climate Action Challenge. Concave Roof is a fine example of a project which takes on the challenge of water scarcity, considers its regional and local context, and does all in a low-tech but high-impact way.

Learn more about the topics, regions and design approaches related to the WDCD Climate Action Challenge by visiting our platform.

All images BMDesign Studios


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