This chapter provides a comprehensive review of recent advances in methodologies for long-term energy consumption forecasting, with a particular emphasis on integrating environmental constraints such as greenhouse gas and air pollutant emission restrictions. The review covers a range of methodological approaches used for forecasting energy consumption at various hierarchical levels, including individual sections, subsections, groups, classes, and industries or services. The paper proposes the integration of three types of mutually agreed mathematical models to enhance the forecasting process. These include: (1) lifecycle models that analyze the development and operation of major technological facilities at the enterprise level, (2) simulation models that track the transit flows of energy resources across Ukraine, and (3) forecasting models focused on specific economic sectors. The integration of these models aims to provide a more accurate and comprehensive understanding of long-term energy consumption patterns and their implications for emissions and environmental constraints. In addition, the paper highlights the importance of considering emissions from energy-intensive sectors, particularly electricity consumers. It discusses methods for calculating emissions based on reference indicators, including both direct emissions from production and indirect emissions resulting from electricity consumption. The paper also addresses the interchangeability of electricity and fuel in the emissions calculation process and provides recommendations for adjusting reference indicators to reflect the ratio of direct to indirect emissions. The review draws on methodologies previously employed by the Institute of General Energy of the National Academy of Sciences of Ukraine and prominent researchers.