With the improvement of the thermal insulation performance of building envelop, the influence of internal factors represented by occupant behavior have become the most important uncertain factors that impact cooling loads and energy consumption. With field test, it was found that the practical occupancy rate in the office buildings was only 40%~60% of that the cooling design condition and the power intensity of office equipment was also lower than 20 W/m². Oversized chillers were also related with over-estimated occupancy rate and equipment power intensity. With reconsideration of these coefficients, the "representative cooling load" was proposed to replace the separated occupant and equipment cooling loads, and modified the cooling results of the case buildings. Comparing with the maximum measured cooling load during testing period, assurance rate of modified cooling load were more than 90%.