Performance based design is an approach to complying with the code or developing alternative compliance using engineering principles. Most commonly, performance-based design is used to evaluate the smoke control system within an atrium, determine the egress time of a building or assist in the sizing of stairwell and elevator pressurization systems. Typically, mechanical engineering firms will utilize hand calculations in order to estimate the total exhaust rate for a smoke control system. Using this one-size-fits-all approach, there are multiple inefficiencies that can be caused on the project.