Building simulation software alone can sometimes fall short of providing a reliable building model. The user can improve the fit by using empirical data to fine tune the simulation and properly reconcile the building's loads and it's systems' operations. The empirical data may take various forms but will generally include metered utility data and information from site visits and load monitoring. This entire process can be assisted using computerized techniques which in themselves model the building's energy balance. Together with the building simulation program this technique provides the user with a reliable base building model from which to model other building load and systems' scenarios. This paper will deal with the experiences of the author in using the building simulation program LOADSHAPER along with data gathering techniques and an in-house computer program TRACKER to properly reconcile building simulation models. These are described below. LOADSHAPER is a building simulation program marketed primarily to utilities in support of demand-side management and strategic conservation programs which support planning, marketing, load research and customer service areas at the utility. The program calculates space heating and cooling loads on an hourly basis, following the 1985 ASHRAE handbook. it calculates HVAC and plant performance using algorithms from the Lawrence Berkeley Laboratory DOE?2 Engineering Manual and the ASHRAE TC4.7 modified bin method, extended to use a four point interpolation of solar gains. The program provides for quick and intuitive choices of building parameters with systems' selection and design support. This particular building simulation program was chosen primarily for it's ease of use, flexibility, speed of execution and reference documentation. TRACKER is a spreadsheet model which requires the user to input metered utility data, local weather data and building end use loads and profiles. In return, the model provides tabular and graphical reports on building monthly end-use profiles and annual totals. TRACKER was developed to enable engineering staff to easily and quickly reconcile building loads and profiles from utility metered electrical and fuel data. Building load information for both LOADSHAPER and TRACKER is generally obtained through site visits, a review of mechanical and electrical drawings and interviews with building operating staff. Cyclic and intermittent loads may also be monitored using current recording equipment providing demand and energy use levels and schedules.