The design of industrial facilities is often dependent on the layout characteristics. Thus, a simultaneous approach to the design and layout of facilities is an important problem to be addressed. In this paper, the simultaneous design and layout of an industrial facility is studied, taking into account interactions that might be relevant when designing industrial facilities. The model developed here is essentially focused on the layout characteristics, whereas the design aspects are addressed more simply by considering the possible. existence of a certain equipment item, or connection. This, is determined by adequate design models based on the specified industrial design characteristics (as will be explored in part II of this work; see following paper). The proposed model has therefore the particularity of being adjustable to alternative design problems. In this way, different operational and topological problem characteristics can be addressed often dictated by the type of plant being designed (e.g., flow-shop or job-shop structures and operations such as continuous of batch plants). The optimal plant layout is obtained through the minimization of the connectivity cost, where different topological and operational characteristics are considered, along with equipment costs over a two-dimensional continuous area. The model leads to a mixed integer linear problem (MILP) in which binary variables are introduced to characterize design and topological, choices and continuous variables are used to describe the distances and locations involved. To conclude, the applicability of the proposed formulation is illustrated through a set of representative examples.