In this paper, we present activity models of chemical process design integrating environmental, health and safety (EHS) evaluation as a new element with conventional economic and technical considerations on the basis of the design framework, which defines different stages of early process design with appropriate indicators for multiobjective evaluation. The type-zero method of Integrated DEFinition language or IDEFO is selected as an activity modeling method for the hierarchical and transparent description of complex design activities. The viewpoint of the activity model is the user of this design framework, i.e. a design-project manager who leads a group of process chemists and engineers. A set of template models is developed, which describes how a manager executes a project step by step with providing instructions and resources appropriately. According to this template, IDEFO models of the design framework are created, and here EHS-related activities, tools and information are systematically defined as a part of (he whole design activity. As further analysis, sub-activities are presented in detail, where the manager allocates resources appropriately to different design stages, including methods of environmental Life Cycle Assessment (LCA) and EHS hazard evaluation. Another detailed analysis is on how design constraints, e.g., market situation, competitors' patents and company culture, affect different decision-making within the framework. The actual development of methyl methacrylate (MMA) processes is investigated as a case study. The paper finally presents important know-how for the design manager in executing the integrated design framework.