This paper presents an integrated framework comprising of two computer aided systems, ENVOPExpert and SustainPro, for sustainability assessment of chemical process plants. Analysis based on ENVOPExpert diagnoses the waste sources, identifies heuristic design alternatives and highlights trade-offs between the environmental and economic objectives. The Indicator model of SustainPro evaluates further these alternatives and screens them at an in-depth level through its sustainability metrics analysis to identify sustainable design alternatives. The application of the framework is illustrated through an ammonia production case study. © 2009 Elsevier B.V. All rights reserved.