The modelling of complex technological systems serves as the foundation for enhancing process performance, including sustainability features (triple-bottom line). The European Green Deal, proposed in 2019, aims to cut greenhouse gas emissions by 2050 and foster a resource-independent economy. Such a change must be carefully planned. Comprehensive sustainability protocols and guidelines are necessary to describe the standardized methodological procedure, the environmental certification procedures that allow market comparability and identification of the best solutions, the databases, the calculation tools and software, and the benchmark and target with which to make comparison. Policies and regulatory or incentive instruments promote the broad adoption of these approaches and ensure that policies reduce environmental, economic, and social impacts. This paper consists in an overview of sustainability assessment tools' role in energy policy and shortand long-term modeling of more eco-friendly energy-product systems. Additionally, the paper explores these methods' pros and cons in planning, analyzing, and optimizing energy/product systems, also according to the circular economy paradigm. All of these strategies aim to help the decision-maker make more consistent judgments by taking into consideration essential objective, such as end user or stakeholder demands, and minimizing subjective elements. An extensive listing of Sustainability accreditation and communication tools is provided. Sustainability assessment is an evaluation and optimization method that promotes sustainable development in all political planning and decision-making. It examines the social, economic, and environmental effects, finds conflicting goals, and recommends early optimization. Potentially, sustainability assessment should be integrated into the political planning process and depend on domain-specific research and assessments that currently exist or are planned, such as in combination with decision-making. Sustainability assessment is not designed to be an extra analytical tool. A sector-specific environmental or economic study from a strategic environmental analysis or regulatory effect analysis may be crucial to a sustainability assessment.