PRI projects have large impacts on various sustainability attributes in different phases. A comprehensive assessment of these impacts for project's life-cycle is of great importance. The proposed methodology has created the required framework for such assessment by using Concept Mapping, Focus Group, and Multi-Attribute Decision Making Techniques. Petroleum refi nery industry (PRI) is comprised of a chain of expertise and engineering disciplines and is also connected to various other industries. Consequently, apart from its physical products that fulfi ll the fuel needs of the society, PRI has a great contribution to economic development and to the prosperity of different businesses. On the negative side, however, PRI is one of the primary contributors to global warming and other environmental issues and could have some unwelcome effects on the society as well. Hence, development of these projects should be done with careful assessment of their life-long impacts from a sustainability viewpoint.In this study, a sustainability framework for PRI projects, which was developed and presented in a previous publication, is used in a multiphase methodology to assess the relationship between lifecycle phases and sub-phases of a petroleum refi nery on one hand, and sustainability indicators and factors on the other hand. As a result of this study, critical sustainability factors can be highlighted, to help managers and industry experts consider long-term sustainability consequences in their decision making process. The proposed methodology has been applied to a real petroleum refi nery project, using an MADM-based scenario approach, to assess the correlation between sustainability factors and various life-cycle phases and sub-phases of the refi nery.Based on the results, the most important phase in the petroleum refi nery life-cycle with regards to all three pillars of sustainability is found to be the operation phase. As such, implementation of various operation phase sustainability aspects should be the fi rst priority of stakeholders during design, procurement, construction, and operation phases.