Via Gulliver, a Chinese company has built a 30-story hotel in Hunan Province from prefabricated, energy-efficient parts:
From Next Big Future:
The buildings are five times more energy efficient in operation and use about 6 times less cement.
They plan to build one hundred and fifty 30-story apartment building, hotel, office plans using the new system. They have started building a 1.33-million-square meter “NO.1 Sustainable Building Factory” and it will be able to produce 10 million square meters of mass produced skyscrapers each year. The 30 story building is 17,000 m² so the factory can produce about 500 of the 30 story building each year and many more factories will be built.
It did take a while to build the parts that they assembled at the building site, of course. But even then, the building cost 2/3 less than similar buildings to construct.