text: However, Vauban is not the only commmunity that has used a movement called "smart planning", which is the separation of suburban life from auto use. The trend is growing in Europe, in the United States, as well as other places. Experts say that the method is an effort to greatly reduce greenhouse gas emissions from tailpipes. In places like Europe, passengar cars are responsible for 12 percent of greenhouse gas emissions. While places in the United States that has a high car usuage number is responsible for 50 percent of greenhouse gas emissions.