The Building Systems Engineering Handbook is a comprehensive professional reference for engineers, architects, inspectors, contractors, and facility professionals involved in the design, coordination, and management of modern building systems. Covering Electrical, Mechanical (HVAC), Plumbing, Fire Protection, and Low-Voltage (ELV) systems, this handbook integrates all MEP disciplines into one cohesive resource with practical examples, coordinated diagrams, code references, and field inspection checklists. Organized across seven parts and six appendices, the handbook covers: power distribution and emergency systems, lighting design and controls, fire alarm and suppression systems, plumbing supply and drainage, HVAC load calculations and energy efficiency, CCTV, access control, intrusion detection, structured cabling, and Building Management Systems (BMS/BAS). The integrated sample project — the Riverside Business Center — demonstrates full MEP + ELV system coordination with detailed equipment schedules, riser diagrams, and commissioning procedures. Designed for real-world application, each chapter follows a consistent structure: concept overview, components and architecture, design principles, testing and commissioning, and integration notes. Professional Insight callouts throughout highlight code-critical nuances, field-tested techniques, and common pitfalls that experienced engineers encounter on live projects.