3D printed “Cool Brick” is an air conditioner that only needs water to work
The technique known as 'evaporative cooling' has been used as far back as 2500 BC to cool homes in hot, dry climates with simple materials. When you add water vapor to air, it cools down; and a company called Emerging Objects has integrated that concept into a 3D printable, porous ceramic bricks held together by mortar. The latticed structure allows air to pass through, freely, and the water that is held inside the micro-pores evaporates, cooling the vicinity.
It's a commen technique in the cooling industry, with many companies employing the idea in technologies that range from simple to complex, but the ability to 3D print your own cooling system is remarkable.
The Cool Brick will be on display in San Francisco from January 17 to April 19, 2015. This particular iteration can be printed and pieced together, like LEGOs.
Another valuable effect from this type of cooling is that it is a natural humidifier.
Here's a brief example of how evaporative cooling occurs and how drastically it can effect the temperature if used properly
http://inhabitat.com/3d-printed-cool-brick-cools-a-room-using-only-water/