The design and installation of an air conditioning system may be carried out properly, but if it is not adjusted and balanced to meet design conditions, it will not perform satisfactorily. The complexity of modern air conditioning systems may make the balancing process quite involved. Even some experienced personnel frequently are unaware of the difficulties and requirements of balancing. In the past it was often possible to get by with making a few adjustments and checking if people were comfortable. This is no longer satisfactory on large systems. Organized procedures are required to balance a system so that it will result in comfort in all seasons. Furthermore, the increased need for minimizing energy waste also requires correct balancing techniques. An improperly balanced system will almost certainly use excess energy. The testing and balancing process is often carried out by the contractor upon completion of the installation but for large systems a whole new profession has grown, with organizations and specialist who do only this work. This has happened not only because of the complexity of the task, but it also means an independent organization verifies that the system is operating correctly.