This residence hall in the Netherlands doesn’t boast many of the high-tech, eco-friendly systems that other dorms on this list do, but it’s environmentally conscious in its own way. The dorms are made of shipping containers, recycled when they were no longer needed for their original purpose. Keetwonen is the largest container city in the world, housing hundreds of students and is the second most popular dormitory in Amsterdam. The containers make surprisingly good housing, as they are private, well-insulated, and spacious. Even better, they make use of recycled materials and rely on natural light, monitored ventilation systems, and other features which can be a big boon for saving energy and materials.