Principal Mechanical Design Engineer

Principal Mechanical Engineer – Building Services

Location: South Croydon or London Bridge

Working Pattern: Hybrid (3 days in office, 2 from home)

Are you a hands-on Principal Mechanical Engineer ready to lead complex, high-value building services projects while mentoring a talented team? This opportunity sits within a long-established building services consultancy with more than 30 years’ experience delivering MEP projects across the UK.

About the Organisation

This respected engineering practice specialises in healthcare, commercial, leisure, high-end residential, industrial, defence and education sectors.

What sets them apart:

• A deep engineering heritage, successfully delivering building services engineering projects for over 25 years.


• A strong sustainability ethos with expertise in low-carbon design, renewable technologies, and modern environmental engineering.


• A stable team with decades of combined experience, working with well-known national and international clients.


• Operating primarily across London and the South, backed by strong client relationships and repeat business.

With a strong delivery-focused culture, this is the ideal setting for a senior mechanical engineer who wants influence, responsibility, and meaningful impact.

The Role

As a Principal Mechanical Engineer, you will take full technical and leadership ownership of multiple building services projects across varied sectors. Responsibilities include:

• Leading mechanical engineering design across healthcare, commercial, leisure, industrial and high-end residential projects.


• Developing detailed mechanical design concepts, remaining hands-on throughout all project stages.


• Managing and mentoring a small team of mechanical engineers, ensuring technical quality and delivery excellence.


• Working closely with multidisciplinary colleagues to craft integrated, sustainable building solutions.


• Representing the practice in client and design team meetings, articulating strategy and technical direction.


• Contributing to feasibility studies, condition surveys, and wider MEP coordination where needed.

What Makes This Opportunity Attractive

• Hybrid working – choose between South Croydon or London Bridge offices, with flexibility to work from home two days a week.


• Join a consultancy that is ISO 9001 accredited and Constructionline registered, recognised for its consistent quality and assurance standards.


• Exposure to a wide range of services including MEP design, feasibility studies, low-carbon solutions, renewable technologies, EPC/DEC assessments, and contract administration.


• A leading practice in low-carbon design and sustainable engineering, integrating renewable and energy-efficient solutions across projects.


• An experienced leadership team with a collaborative, hands-on approach that supports professional growth and autonomy.

Who We’re Looking For

• An experienced mechanical engineer with substantial building services consultancy experience.


• Someone who thrives in a hands-on technical role, leading design while managing projects effectively.


• A confident leader who can guide a small engineering team and elevate technical standards.


• Experience in healthcare, commercial, residential care, leisure, or industrial sectors is advantageous.