It is true that most of the world's urban areas are becoming larger, with megacities like Delhi, Jakarta, Shanghai, Beijing and Manila adding more than five million people in the last decade and most other urban areas are growing, but not as fast.
1 With professional installation, a central vacuum system can cost $800-$4,000, but averages about $1,200-$2,000 for new home construction (or as part of a remodeling project where the walls are already torn open) and $1,500-$2,500 for retrofitting an existing house.
Inside the vacuum is an electrical motor, which converts electrical energy into mechanical energy. While the generator and the vacuum (or any other device powered by a motor) may serve different functions, they are actually two sides of the same coin.