The Eco Cooler is reportedly the world’s first-ever ‘zero electricity’ air conditioner, and its inventor wanted to get the concept out there to help as many people as possible. The Grey Group stepped in to help, using its position as a multinational advertising firm to put the plans online, at no cost, so that anyone can build their own Eco Cooler system. Volunteers from Grameen Intel Social Business helped build and install the units, as well as teach locals how to make them, so the wisdom can be passed on.

The Eco Cooler method is fairly simple, from a construction standpoint. A board is cut to fit the desired window, and bottleneck-sized holes are cut out in a grid pattern. The bottoms of empty plastic bottles are cut off and discarded, leaving funnel-shaped bottlenecks that are placed on the grid. That’s all there is to the Eco Cooler, except for the task of installing it in place of the regular window. When mounted, the wider part of the bottles faces outward and catches the passing wind, literally funneling cool air into the building’s interior.

 The efficacy of the Eco Cooler varies widely based on conditions, but Grey Group reports it has the ability to reduce indoor temperatures as much as 5 degrees Celsius, which is on par with what an electric centrally installed air conditioning system can do.