This paper focuses on the evaluation of sustainability in computer-based projects. This type of evaluation has been discussed within the Sustainable Human-Computer Interaction (SHCI) community for a long time and is still considered an unresolved issue. Our paper focuses more particularly on the evaluation framework known as Sustainable Computing Evaluation Framework (SCEF). Here, we describe how such framework can be improved in several ways, and also contribute to the development of the SCEF by a better understanding and integration of sustainability dimension within computer-based projects. This main proposal is composed of three complementary contribution elements. The first contribution element concerns the categorization of socio-environmental impacts as direct, enabling and structural impacts to ensure a global view of impacts over the whole life cycle. The second contribution element concerns the enhancing of the competencies of IT managers through their engagement with the modified SCEF model. The last contribution element includes a feedback loop in the model to compare the estimation of impacts with field data.