At the preliminary planning stage, it is useful to have a rough idea of the number of elevators required for the building and the approximate floor space they will require. Selection of the capacity, speed, and number of elevators for a particular building type is dependent on many interrelated factors. Detailed calculations can become quite complex, as the final solution is a balance between level of service, floor space required, and cost. The following procedure simplifies making preliminary estimates, based on information that is usually known early in the schematic design process. It can be used for relatively simple building types such as low-rise office buildings, residential buildings, ...