Principal Mechanical Engineer (Data Centres and Mission Critical

We have an exciting opportunity for a Senior / Principal Mechanical Engineer to join our Data Centre & Mission Critical (MCDC) team at Hoare Lea. Data centres are central to the modern economy and the technology that powers them is evolving rapidly. Our Mission Critical team helps clients navigate these changing requirements. At Hoare Lea you'll gain a truly unique experience working across the full spectrum of the data centre sector - from early-stage site appraisal, master planning and feasibility studies through detailed plant and HVAC design, live plant upgrades, test-fits, commissioning and operational optimisation.

You'll work across close-control environments, data halls, live plant replacement and refurbishment, critical engineering and due-diligence reviews of existing facilities. Projects span mainly in UK, but also across Ireland and Europe. You will join a collaborative, knowledgeable and highly engaged team with a positive, supportive and flexible culture. Working alongside the Project Leader, you will engage directly with clients, develop designs and produce reports, specifications and guidance, and support testing and commissioning activities to deliver consistent, high-quality outcomes.

In this key and varied role you will:

• Lead day-to-day mechanical design delivery for data centre and mission-critical projects.
• Act as a client-facing engineer, attending meetings, translating briefs and coordinating multidisciplinary inputs.
• Prepare and review mechanical design deliverables, specifications and technical reports.
• Support site appraisals, master planning, feasibility and test-fit studies.
• Oversee plant design, testing, commissioning and handover activities.
• Support monitoring of fees, resources and project delivery.
• Mentor and develop next-generation engineers.

• Proven experience as a Mechanical Engineer delivering mission critical and data centre projects.
• Experience with Revit, BIM workflows and AutoCAD.
• Strong knowledge of HVAC, chilled water and refrigerant systems, cooling plant, air distribution, heat rejection and high-density / liquid cooling technologies.
• Demonstrable client-facing consultancy experience.
• Excellent technical judgement and a collaborative mindset.
• Experience mentoring and supporting others.

• Mission-critical and data centre mechanical engineering across new-build, live operational upgrades, technical due diligence, feasibility studies and test-fits.
• Large-scale, multi-megawatt data centre developments.
• Hyperscale, colocation and enterprise/research environments.
• Early-stage site appraisal, master planning and test-fit studies.
• Cooling infrastructure and heat-rejection options.
• Resilience and uptime design thinking.
• High-density and AI-ready cooling.
• Live operational environments and phased upgrades.
• Campus-scale developments and multidisciplinary coordination.
• Energy efficiency and sustainability in mission-critical design.
• Experience working across the UK; international experience is desirable

Hoare Lea is a human-centric and planet-conscious engineering consultancy. We offer intelligent and sustainable solutions to complex design challenges for the built environment throughout the UK and further afield. We provide a wide range of engineering and consultancy services, including acoustics, air quality, building services (MEP), fire, lighting, security and sustainability to name but a few. Together, our highly skilled teams use technical expertise and problem-solving skills to bring buildings to life.

We ensure that whatever the building, its design is outstanding, and its operations meet the needs of the communities it serves. We are as committed to providing an environment where everyone can realise their unique potential. So, in joining Hoare Lea, you will experience a business that enriches your knowledge, supports your wellbeing, and welcomes your individuality. You'll have the opportunity to participate in our 9-day fortnight scheme, thriving community groups, varied social and networking events, and extensive professional and technical development schemes.

We also offer an extensive benefits package, including private medical cover, an electric vehicle salary sacrifice scheme, stock options, and 25 days of annual leave (increasing with service), alongside flexible and hybrid working. Whatever your ambitions or circumstances, our aim is to enable everyone to develop their knowledge, give their best, and enjoy what they do.