Building performance assessment is a process of using a numerical model “simulation tool” of both the building and system metrics to predict performance. The decision to choose a suitable simulation tool is a continuous challenge. Issues such as model data availability, integrity, and applicability add additional constraints to the modeling process. This paper will discuss the process of using different building simulation tools to identify a credible building energy performance indicator. A typical building is modeled using different tools utilizing similar input data and weather conditions. The output results are compared against actual utility metered data. A series of building performance experiments are conducted and the resulting trends are compared to real-time metered data. The paper presents a pilot project to create an energy benchmarking tool for facility managers and the challenges facing the development team. Finally, the paper proposes a framework to integrate the building performance indicators with urban level indicators to produce an aggregated urban energy performance index.