This thesis project designs a unified simulation and analysis system for pedestrian occupancy density tracking to optimize the use of building space and energy usage that will meet the requirements of EU Directive 2023/1791. The system is made up of two cooperating components, one pedestrian simulation engine to predict real scenes for movement in different room configurations, and the other a matching algorithm to reconstruct whole trajectories for a pedestrian from observation data. Between them, these elements are valuable for developers, as they help building managers to study the occupancy behaviors, check for underused spaces and then to take data-based decisions for both reduction of footprint and improved energy efficiency.