The purpose of the 3rd International Conference on Smart Grids and Green IT Systems (SMARTGREENS) is to bring together researchers, designers, developers and practitioners interested in the advances and applications in the field of Smart Grids, Green Information and Communication Technologies, Sustainability, Energy Aware Systems and Technologies. Green Computing is nowadays one of the major challenges for most IT organizations that involve medium and large scale distributed infrastructures like Grids, Clouds and Clusters. The conference will focus on solutions for all aspects of green computing such as energy efficiency, carbon footprint reduction and cooling management. The tradeoffs between energy efficiency and performance have become key challenges that must be addressed in both, distributed and traditional performance-oriented infrastructures. Particularly relevant is the so-called Smart Grid technology, seeking to optimize distributed electricity generation, especially from renewable sources, and to promote the use of smart devices (including smart home and new vehicular energy approaches) that require further research on distributed communications, energy storage and integrations of various sources of energy. Papers describing advanced prototypes, systems, tools and techniques and general survey papers indicating future directions are also encouraged. Papers describing original work are invited in any of the areas listed below. Accepted papers, presented at the conference by one of the authors, will be published in the Proceedings of SMARTGREENS. Acceptance will be based on quality, relevance and originality. Both full research reports and work-in-progress reports are welcome. There will be both oral and poster sessions. Special sessions, dedicated to case-studies and commercial presentations, as well as tutorials dedicated to technical/scientific topics are also envisaged: companies interested in presenting their products/methodologies or researchers interested in holding a tutorial, workshop or special session are invited to contact the conference secretariat or visit the SMARTGREENS conference website.