In this project, generating sets (Genset), installed in a pre-cast concrete enclosure complete with a forced draught ventilation system was modelled using CFD. The engine in the Genset was a 24-cylinder Jenbacher (J624) and there were multiple strict design criteria in this project which had to be satisfied by accurate CFD simulations. After developing a detailed model of the engine, its components and the ventilation system in the enclosure, various scenarios were modelled to identify any potential Genset de-rating due to excursions beyond operational envelope limits. Other key metrics such as air change per hour, maximum temperature and gas concentration were also obtained and were used to optimize the design of the plant. The CFD model was designed carefully to ensure all the heat sources within the domain are captured accurately by incorporating a series of customised functions and boundary conditions for key heat generation components such as the generator and air intake pipes. The results enabled the client to make crucial design modifications to ensure safety and compliance with appropriate standards and regulations.