In Julie Jacko and Constantine Stephanidis (Eds.), Human-Computer Interaction: Theory and Practice, Part I (pp. 133-137). Mahwah, NJ: Erlbaum. Ecological Interface Design in Practice: A Design for Petrochemical Processing Operations Greg A. Jamieson University of Toronto Toronto, Canada jamieson@mie.utoronto.ca Wayne H. Ho IBM Canada Ltd. Markham, Canada who@ca.ibm.com Dal Vernon C. Reising Honeywell Ltd. Minneapolis, USA dalvernon.reising@honeywell.com Abstract This paper describes the design of an ecological interface for an existing petrochemical process. We describe the iterative design process by example and identify the challenges of applying the Ecological Interface Design framework in industry using a user-centred design approach. 1 Introduction Ecological Interface Design (EID) is a framework for designing graphical user interfaces (that is, ecological interfaces) for complex systems (Vicente & Rasmussen, 1992). Over the past decade, researchers have reported substantial progress in applying EID to a variety of work domains of increasing complexity (see Vicente, 2002). However, the literature lacks depth in two key areas. First, it offers few applications of the framework to real work domains. Second, it tends to focus on the design product rather than on the design process (cf. Reising & Sanderson, 2002). These two characteristics limit the usefulness of the EID literature for industry practitioners who might consider designing ecological interfaces for applied problems. The two objectives of the work discussed in this paper were: a) to extend the literature by applying EID to an existing industrial process, and b) to identify the challenges of applying EID in a user-centred design process in industry. We designed a novel graphical user interface for an ethylene manufacturing process. EID formed the basis for an iterative design approach that incorporated several types of user feedback. Although EID does not contradict other user-centred design approaches, its emphasis on using work domain analysis to identify information requirements may reduce the attention that designers devote to acquiring user feedback in the design process. This has been compounded by the fact that there have been no expert users of the laboratory microworld simulations for which most ecological interfaces have been developed. Given that we were working in an industry setting with a population of domain experts as users, stakeholder acceptance of the designs was critical. The target domain is a sub-process of an ethylene refining plant. The reactor converts acetylene in a hydrocarbon stream into ethylene by reacting acetylene and hydrogen in the presence of a catalyst. However, other hydrocarbons in the process stream will react with hydrogen as well, giving off heat and destabilizing the reactor. The operator must balance hydrogen consumption, reducing the acetylene concentration in the product stream to below 5 ppm and minimizing excess hydrogen. This is done by regulating the flow rate of the mixed hydrogen stream.