INTRODUCTION An air handling unit (AHU) connects primary heating and cooling plants with building zones@ controls building ventilation intake@ and greatly affects the energy consumed for heating@ cooling@ and ventilating@ as well as supply air temperature and humidity levels. An AHU's operation significantly impacts building energy use@ health@ and comfort aspects. Nevertheless@ only limited experimental studies under restrictive scopes were available to evaluate AHU automated fault detection and diagnosis methods (Norford et al. 2000@ Carling 2002@ Castro et al. 2003). A dynamic AHU simulation model that is capable of producing fault free and faulty operation data for commonly used AHU configurations@ and control and operation strategies is thus needed. Moreover@ developed dynamic AHU simulation models need to be properly validated systematically with experimental data for both fault free and faulty operation before any credibility can be placed on the prediction accuracy and usefulness. Therefore@ developing and validating a dynamic AHU simulation model that is capable of producing fault free and faulty operation data are objectives for an ASHRAE research project (RP-1312). In this twopaper series@ the fault free model development and validation processes are summarized. Fault model development and validation process will be reported in the future. The objectives of this study are to: (1) identify the proper simulation program and develop a full scale dynamic AHU and building zone system model that has the capability to produce fault free operational data; (2) identify a proper test facility and gather experimental and/or field data to validate the developed system model; and (3) develop a validation strategy and validate the developed AHU model (reported in Li et al. 2009).