Process intensification (PI) has the potential to improve existing processes, necessary to achieve a more sustainable production. PI can be achieved at different levels. That is, the unit operations, functional and/or phenomena level. The highest impact is expected by looking at processes at the lowest level of aggregation: phenomena. Therefore, in this paper, a phenomena-based synthesis/design methodology is presented. Using this methodology, a systematic identification of necessary and desirable (integrated) phenomena as well as generation and screening of phenomena-based flowsheet options are made using a decomposition based solution approach. The developed methodology is highlighted through a case study involving the production of isopropyl-acetate.