Efficient energy operation of microgrids that include a localized group of controllable loads with distributed energy resources (DERs) requires the development of energy management systems (EMSs) with the ability of controlling the loads so that the aggregate performance of the microgrid can be optimized. This paper proposes a bi-directional EMS framework used for an office building including photovoltaic panels (PV), an energy storage system (ESS) and a combined heat and power (CHP) microturbine. A simplified building thermal model is developed for predicting and characterizing the thermal demand. The developed mixed integer linear programming (MILP) model utilizes two-way energy exchange using net metering technology and incorporates an optimizer which decides the power flow among the DERs components of the microgrid so as to minimize electricity cost and in the same time ensure the thermal comfort of the occupants. Simulation results demonstrated the individual energy contribution of each DER in the system and confirmed the effectiveness of the proposed approach.