The Windball is a conceptual air conditioner that chills a room using evaporated water. Windball is solar-powered and was designed by Jaesik Yun. To use the device, simply fill it with water and charge its solar battery. The water cools the air as it evaporates and the electric battery spins the Windball to propel the cool air around the room.
According to Yun, one Windball can lower the temperature of air by as much as 3 degrees Celsius. The idea behind the Windball is to use many at once so that you get the same cooling effect as an air conditioner without the enormous electricity use. In addition to not using nearly as much electricity as an air conditioner, the Windball also looks a lot nicer in a window than a bulky AC unit.