This paper introduces a Human And Building Interaction Toolkit (HABIT) for simulating the thermally adaptive behaviors of office building occupants alongside energy use and thermal comfort as part of whole building performance simulation (BPS). The toolkit co-simulates an agent-based model of occupant comfort and behavior in MATLAB with whole building energy simulation in EnergyPlus using the Building Controls Virtual Test Bed (BCVTB). A general overview of this exchange and its user setup is provided, followed by a description of the fieldvalidated occupant behavior algorithm that the exchange relies upon. The toolkit is then used to simulate the energy and comfort effects of occupant behavior in a medium-sized office building across each of the five U.S. Department of Energy climate regions. Results reveal that the inclusion of realistic behavior increases a building thermal zone's total expected energy use by up to 15% in the winter in cold climates; however, if building managers were to pair the provision of more efficient personal heating/cooling devices with increases in thermostat set point ranges, it is expected that total energy use would not increase significantly in perimeter zones in the winter and would significantly decrease in all zones the summer (up to 32%), while thermal discomfort would be significantly reduced in all zones in both seasons. These effects are generally consistent across the simulated climates.