Nexus BMS is an advanced building management system that transcends traditional solutions by integrating real-time monitoring, direct equipment control, and predictive AI diagnostics into a unified platform, capable of transforming building automation from reactive to proactive management. Unlike conventional systems that merely collect and display sensor data, Nexus actively controls building equipment using time series data to detect issues early and adjust operations automatically, enhancing reliability, efficiency, and safety in diverse environments such as clean rooms and healthcare facilities. This system utilizes InfluxDB for time series data management, NodeJS for backend programming, and Raspberry Pi controllers for executing control commands, supported by AI models trained with historical data to enable predictive maintenance. The use of open-source hardware and modern data infrastructure empowers Nexus to continuously process thousands of sensor readings and apply custom control logic, ensuring optimal performance and preemptive issue resolution, thereby providing a robust solution for facility managers dealing with challenges such as broken controllers and rising licensing fees.