My group presentation a couple of weeks ago on the topic of commercial and residential buildings showed a video about a 30-story hotel built in 15 days in Changsha, China. This article from the LA Times further explains the project. Presently in the US we cannot construct a building so quickly because risk is a major concern to us. We require many more inspections and checks along the way. Also, we do not do construction at night because that can be risky as well. In China, there are fewer regulations allowing them to complete such large projects in a fraction of the normal time. This particular building has green systems in the design, including low flush toilets, efficient lighting systems, and less concrete in construction, which is a major contributor to greenhouse gas emissions due to the cement.