Principal Mechanical Engineer - HVAC & Building Physics (Remote) Fully Remote £60/hr Inside IR35 12-Month Minimum Contract We're seeking an experienced Principal Mechanical Engineer to support a major defence infrastructure programme delivering critical M&E systems across Building C and Southern Services within the 10 Dock development. This is a fully remote, long-term contract opportunity focused on HVAC design, substantiation, and multidisciplinary coordination within a highly regulated environment. The Role You'll lead mechanical design activities across concept, scheme, and detailed design stages, with particular responsibility for HVAC systems supporting substation infrastructure and occupied operational spaces. Key responsibilities include: Delivery of RIBA Stage 3 and Stage 4 mechanical design HVAC and controls design for critical environments Design and substantiation of central and local ventilation systems Chilled water system design supporting electrical plant areas Coordination of thermal modelling activities and building physics assessments Supporting FMECA, HAZID/HAZOP, and nuclear safety case activities Mechanical coordination across multidisciplinary teams Input into Basis of Design documentation and designer risk assessments Supporting client liaison, design management, interface coordination, and ECI activities Additional systems include: Void ventilation Gas detection Heating systems ...