Senior / Principal Mechanical Design Engineer – Building Services Location: South Wales | Salary: Competitive Package Job Type: Full-time, Permanent Lead Mechanical Design, Mentor Talent, and Deliver High-Quality Projects A well-established and highly respected Building Services Contractor in South Wales is seeking a Senior / Principal Mechanical Design Engineer to strengthen their in-house mechanical design team. With a strong pipeline of projects across commercial, education, healthcare, residential, hospitality, and retail sectors, this is an exciting opportunity to take a leadership role with real responsibility. You’ll join a supportive team delivering technically challenging and rewarding projects, from multimillion-pound new builds to complex refurbishments, while having the chance to mentor junior engineers and shape the future of the department. Key Responsibilities Lead mechanical design on projects from concept through to completion Attend and chair design and coordination meetings with internal and external teams Act as the main point of contact for clients, representing the business professionally Ensure all designs comply with UK building regulations, CIBSE guides, and industry standards Develop detailed designs using software such as Hevacomp, IES, Revit, and AutoCAD Review and oversee drawings, schematics, and specifications Mentor and support junior engineers, apprentices, and wider design staff Report project progress to the M&E Design Director Collaborate with the in-house construction team and multidisciplinary stakeholders What We’re Looking For Degree or HNC/HND in Mechanical or Building Services Engineering (or similar) Proven experience in mechanical building services design, ideally within a contractor or consultancy Strong technical knowledge of HVAC, LTHW/CHW systems, and sustainable design principles Competence with design software (Revit, IES, AutoCAD, Hevacomp) Ability to lead projects, take ownership of delivery, and work within budgets Good commercial awareness and client-facing skills Experience in a contracting environment is advantageous, but training can be provided Why Join? Secure, long-term role with a company that invests in its people Competitive salary and benefits package, negotiable depending on experience Flexible working arrangements where required Exposure to a wide range of technically challenging projects Real autonomy and the opportunity to influence the growth of the design function Supportive environment with clear progression opportunities If you’re a Senior / Principal Mechanical Design Engineer looking to take the next step in your career or work on high-quality projects within a company that values its people, apply now or get in touch for a confidential conversation