Mechanical systems drawing is a type of technical drawing that shows information about heating, ventilating, air conditioning and transportation around the building (Elevators or Lifts and Escalator). It is a powerful tool that helps analyze complex systems. These drawings are often a set of detailed drawings used for construction projects; it is a requirement for all HVAC work. They are based on the floor and reflected ceiling plans of the architect. After the mechanical drawings are complete, they become part of the construction drawings, which is then used to apply for a building permit. They are also used to determine the price of the project.