As the importance of energy efficiency improvement andmanagement of existing buildings increases, theimportance of energy simulation and energy useevaluation of existing buildings is also increasing.However, unlike new building, the level of availableinformation that can be entered into the simulation variesfrom building to building. Therefore, in variouscountries were developing and providing a referencemodel of the existing buildings for evaluating energyperformance by using the available information or thestandards according to completion year of the building.However, information that can not be gathered is usuallyinput assumed value by the case study or previousstudies. The ultimate goal of this study is to replace theassumed values of variables with more accurate andreliable information by calibrating the model output withmeasurement data. And, it is to provide which not asingle reference building but a reference building pakagethat can be evaluated to reflect various buildingcharacteristics across the country. This study is a basicstudy for this purpose, to develop a reference buildingpakage for the national-wide offices according to theexisting reference building development method and topresent the calibration direction by comparing it with theavailable information of the existing building.