Principal Mechanical Design Engineer
Location: Hertford, Hertfordshire (office-based with hybrid after probation) Salary: upto 75,000 depending on experience Type: Permanent, full-time
The Opportunity
Our client is an established, multidisciplinary building services consultancy based in Hertfordshire. Founded over two decades ago, they have built a strong reputation as M&E Consulting Engineers and Low Carbon Consultants, delivering technically excellent design solutions for architects, contractors, and end clients across commercial offices, education, healthcare, data centres, and historic buildings.
This is a Principal-level appointment into a tight, growing team that values technical depth, collaborative problem-solving, and proper engineering discipline. They are looking for a mechanical engineer who is genuinely strong on full design, not just concept work, who knows their RIBA stages inside out, and who is ready to take technical leadership on projects and mentor the wider team.
Key Responsibilities
Take principal-level technical responsibility for mechanical design on live projects across RIBA Stages 1 to 4, from inception through to detail design
Own and deliver full mechanical design packages, including HVAC, public health, plantroom layouts, load calculations, specifications, and schedules
Develop low-carbon and energy-efficient mechanical strategies aligned with current Building Regulations, CIBSE guidance, and British Standards
Lead client engagement on assigned projects, presenting design rationale and managing expectations from concept through to delivery
Coordinate multidisciplinary inputs with architects, electrical engineers, structural engineers, and contractors
Provide technical leadership and mentoring to senior, intermediate, and junior mechanical engineers within the team
Review and sign off design output, ensuring technical accuracy, compliance, and consistency across the consultancy
Contribute to fee proposals, project programming, resource planning, and business development activity
Carry out site inspections, condition surveys, and commissioning support as required
Uphold and shape the consultancy's reputation for technical excellence and sustainability-led design
About You
Significant experience as a Mechanical Design Engineer within a UK building services consultancy environment, with a track record at Senior or Principal level
Strong, demonstrable understanding of RIBA Stages 1 to 4, with particular depth in detail design (Stage 4)
Confident producing fully coordinated mechanical designs across HVAC, public health, ventilation, heating, cooling, and plantroom systems
Working knowledge of energy modelling tools (IES VE or similar) and design software (AutoCAD, Revit MEP)
Proven ability to lead client relationships, present design solutions, and manage commercial expectations
Experience mentoring and technically supporting junior and intermediate engineers
Commercially aware, with an understanding of fee management, project programmes, and resource planning
Chartered or working towards chartership (CEng, MCIBSE) is desirable
UK right to work
Local to Hertfordshire or within a sensible commute
You will thrive in this role if you want technical leadership, ownership of your projects, visibility on your work, and the chance to shape the direction of a growing consultancy that genuinely cares about engineering quality and sustainability.
Package
£75,000 basic salary depending on experience
Hybrid working available after successful completion of probation
Pension and benefits package
Clear progression path within a growing consultancy
Active CPD culture and full support towards chartership
Mentoring and leadership development as part of the role
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