During the past decade, a number of studies have reported comparisons of building energy simulations to measured building performance. Over two dozen studies, comprising about 100 simulations of building energy use, have been compiled and categorized by quality of input and energy consumption data, type of study, model used, quality of input and consumption data, expertise of input preparer, and control and monitoring of occupancy. This paper summarizes results of studies of occupied buildings in which monitoring varied from very detailed to nonexistent, the comparison interval from hourly to yearly, and the number of buildings from one to 200-plus. These results are briefly compared to results from unoccupied buildings and preliminary conclusions are presented about the use of building energy models for different types of field applications. This is an ongoing compilation to which contributions both of data and methodological suggestions are invited.