We are seeking an experienced Mechanical Commissioning Technical Team Leader to lead the commissioning delivery team of hyperscale and colocation AI data-centre projects. The role will provide technical leadership, people management and client-facing governance across the complete commissioning lifecycle from L0–L6, with a strong focus on L4 Functional Performance Testing (FPT) and L5 Integrated Systems Testing (IST). This position is site-centric and requires hands-on leadership through Integrated Systems Testing, including failure mode and fault tolerance validation, ensuring systems meet design intent, availability objectives and operational readiness requirements in line with Uptime Institute, IEC, IEEE, and NFPA standards. Key Responsibilities Lead and mentor a team of 15–20+ leads and commissioning engineers. Own mechanical commissioning strategy, planning, execution and technical governance. Lead L4/L5 commissioning, including FPT, IST, failure-mode and concurrent-maintainability testing. Provide technical oversight across HVAC, chilled-water systems, chillers, cooling towers, CRAH/CRAC, AHUs, DX/In-Row cooling, containment and high-density liquid/immersion cooling systems. Lead commissioning of HSD/fuel systems, including bulk/day tanks, transfer systems, filtration, leak detection and generator auto-fuelling interfaces. Oversee fire protection and life-safety systems, including fire pumps, wet/dry/pre-action systems, clean-agent systems, VESDA, dampers and smoke-control systems. Oversee plumbing and utility systems, including water storage, makeup water, drainage, sump systems, leak detection and associated utilities. Review P&IDs, equipment submittals, control sequences, Sequence of Operations (SOO), cause & effect and commissioning test scripts. Lead TAB/hydronic balancing, equipment performance testing, controls/BMS integration and functional testing. Validate mechanical integration with BMS, EPMS, electrical systems, fire/life-safety and data-center controls. Manage commissioning issues, RCA, risk registers, punch lists and technical close-out. Act as senior technical interface with hyperscale clients, CxA teams, MEP contractors, consultants and OEMs. Drive commissioning quality, safety and readiness for operational handover. Requirements 15+ years overall mechanical engineering, testing and commissioning experience. 8+ years data-center or mission-critical mechanical commissioning experience. Proven leadership of at least 2 complete L2 to L5 commissioning cycles. Proven experience of leading at least 2 ISTs of hyperscale datacenter projects. Experience managing 15–20+ Cx engineers. Strong hands-on knowledge of HVAC, chilled-water systems, cooling towers, CRAH/CRAC, BMS/controls, fuel systems, fire protection and utilities. Experience with high-density/liquid cooling is highly desirable. Strong understanding of Uptime Institute, ASHRAE, NFPA and applicable local codes/standards. Strong knowledge of Sequence of Operations, controls integration, TAB, hydronic balancing and failure-mode testing. Bachelor's degree in Mechanical Engineering or equivalent. Strong client-facing communication and technical leadership skills.