Broad Sustainable Building (BSB) is an innovative Chinese architectural firm whose mission is to erect "medium-cost, super-saving utility buildings and to promote a futuristic urban lifestyle." They are planning to build the world's tallest building, the Sky City Tower in Changsha, Hunan, whose 220 storeys will be erected in 90 days. The timelapse video above shows another BSB project, a 30-storey hotel that went up in 15 days. The company claims its designs are extremely seismically robust and environmentally efficient. From CNNGo:

Its 220 stories will provide a total of 1 million square meters of usable space, linked by 104 elevators.

Zhang said Sky City is expected to consume a fifth of the energy required by a conventional building due to BSB's unique construction methods, such as quadruple glazing and 15-centimeter-thick exterior walls for thermal insulation.

The company's construction methods also seem to save money.

According to Chinese newspaper 21 Century Business Herald, the total investment in Sky City is RMB 4 billion (US$628 million), compared with US$1.5 billion on Burj Khalifa and US$2.2 billion on Shanghai Tower.