integrating air-handling unit (IAHU) control theory has been proposed to improve the energy efficiency in office buildings by utilizing the regional and operation differences among multiple AHUs. Unlike the conventional AHU operation, where the units are controlled as independent systems without interaction, IAHU coordinates the AHUs based on the dynamic outside air conditions and system operation modes to achieve synergized energy performance and maintain the indoor air quality. The synergization strategy allows the outside air intake and the airflows to be orderly re-allocated among the AHUs when conditions are appropriate. This paper presents the implementation methodology and performance evaluation of IAHU in an open-plan office building with multiple AHUs. The allocation of airflows among the AHUs is described first to illustrate how IAHU deals with multiple AHUs in a building. The supervisory level control algorithm is then detailed and easy-to-follow flowcharts are provided based on the decision-making schema. A two-step hourly evaluation method and the energy simulation model are introduced. An office building with multiple AHUs is selected to assess the performance of IAHU. The study concludes that the innovative IAHU with the easy-to-implement strategy can be readily implemented to achieve high energy efficiency in open space office buildings. (C) 2012 Elsevier B.V. All rights reserved.