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
• Cold water services

Project Scope
Building C forms part of the wider 10 Dock facility and includes critical substation infrastructure supporting operational dock systems.
Southern Services provides the M&E connections between Devonport infrastructure and 10 Dock, including:

• HV cable routing infrastructure
• Mechanical piped service trenches
• Incoming and outgoing service interfaces

What We''re Looking For

• Principal or highly experienced Mechanical Engineer
• Strong HVAC and controls background
• Experience delivering RIBA 3 and RIBA 4 designs
• Good appreciation of building physics and thermal modelling
• Ability to coordinate substantiation activities and support safety case requirements
• Experience within complex infrastructure, defence, nuclear, or mission-critical projects advantageous

This is a fantastic opportunity to support a high-profile programme with long-term stability, technically challenging work, and fully remote delivery.