Recent progress in BIM to BEM for energy analysis has proven to be effective for early design analysis and parametric evaluations of design options. Several cloud-based simulation strategies have been developed for auto-tuning and model calibration using utility billing data. This presentation summarizes an approach integrating BIM to BIM and cloud-based parametric simulations for developing calibrated energy models from BIM using site specific weather data. It is possible to use the calibrated model in conjunction with parametric design analysis for evaluating retrofit opportunities. Examples are presented to dynamically evaluate retrofit options without performing additional simulations.