The combination of proportional-integral-derivative (PID) coefficients for a set of equipment in a heating, ventilating, and air conditioning (HVAC) system has an impact on the overall system energy consumption as well as the ability for the system to maintain temperature setpoints. A simple calibration methodology is discussed where successive optimization on the set of proportional, integral, and derivative coefficients is performed to reduce the energy consumption of the system. The calibration methodology discussed here is applied to a two-zone building for a summer design day. The results show that calibration of proportional coefficients can reduce the system energy consumption by up to 29% and can improve meeting temperature setpoints by up to 45%. Successive calibration of integral coefficients can increase the energy savings up to 35% and can improve meeting temperature setpoints by up to 52%. The successive calibration of derivative coefficients has a negligible impact on the energy conservation and the ability to meet temperature setpoints. The re-calibration of proportional coefficients with the new values of integral and derivative coefficients yields an additional 2.3% increase in energy savings. (C) 2011 Elsevier B.V. All rights reserved.