From the Architects:
Despite construction problems, the abrupt replacement of the engineer, months long construction delays, and the necessary addition of a PVC membrane over the paper membrane for fire safety issues, the Pavilions has been a great leap forward in the field of paper architecture. The main theme of the Hanover Expo was the environment and the basic concept behind the Japan Pavilion was to create a structure that would produce as little industrial waste as possible when it was dismantled. The goal was either to recycle or reuse almost all of the materials that went into the building. The first structural idea was for a tunnel arch of paper tubes, similar to the Paper Dome. However, the Paper Dome was limited by the high cost of wooden joints. I proposed a grid shell using lengthy paper tubing and without joints to my collaborator, Frei Otto. The tunnel arch would be about 73.8m long, 25m wide, and 15.9m high. The most critical factor was lateral strain along the long side, so instead of a simple arch I chose a grid shell of three-dimensional curved lines with indentations in the height and width directions, which are stronger when it comes to lateral strain.
For more information about Shigeru Ban's 2014 Pritzker Prize, please read http://www.architectmagazine.com/architecture/shigeru-ban-architects-wins-the-2014-pritzker-prize_o.aspx