Role: Senior Mechanical Design Engineer (Decarbonisation & Energy Solutions) Location: Manchester or London (Hybrid working available) Salary: up to £70k plus package The Senior Mechanical Design Engineer is responsible for the delivery of high-quality mechanical designs and technical support across decarbonisation and sustainable retrofit projects. This includes the design and optimisation of HVAC systems, heat pumps, and building automation systems, supporting the full project lifecycle from early feasibility through to construction and commissioning. What will you deliver? Strong technical grounding in mechanical building services design to integrate low-carbon energy solutions, such as heat pumps, heat recovery systems, high-efficiency HVAC, thermal storage, and demand-led controls for sustainable retrofit in commercial, public-sector, and mixed-use buildings. Proven experience in heat pump design and integration, including hybrid systems and low-temperature heating solutions. Ability to integrate mechanical systems with electrical infrastructure and low-carbon technologies for retrofit and new-build projects. Sound understanding of electrical building services to enable effective coordination. Competent in detailed design from RIBA Stage 2 to 5, including heating and cooling load calculations, ancillary equipment sizing and selection, ductwork and pipework sizing, schematics, schedules, DSEAR assessments, and technic...