Energy planning and management is a requirement sustainable use of energy resources which are necessary social, economic or environment sustainability. There is need to balance electricity generation and consumption for safety, supply security and cost monument hence the need for effective modern energy models. Forecasting demand and planning for generation is one of the planning tools to ensure availability of accurate forecast and identifying management decisions.  Energy plan is an energy system analysis tool and methodologies suitable for the design and evaluation of smart energy and renewable energy system alternatives. This study presents the EnergyPLAN model and describe how to use it for the design of relevant alternatives. The is an energy system analysis tool that can be used for study and research in the design of future sustainable energy solutions with a special focus on energy systems with high shares of renewable energy sources. Traditionally disparate demand sectors, such as buildings, industry and transport, are linked with supply technologies through electricity, gas, district heating and cooling grids. In this way, EnergyPLAN enables the analysis of the conversion of renewable electricity into other energy carriers, such as heat, hydrogen, green gases and electrofuels, as well as the implementation of energy efficiency improvements and energy conservation. The structure of EnergyPLAN is discussed and the essential algorithms and computational structure. The EnergyPLAN can analyse coherent energy systems on an aggregated basis and with emphasis on evaluation of potential synergies across subsectors. EnergyPLAN evaluates hourly balances of district heating and cooling, electricity and gas grids involving technologies like heat pumps, cogeneration, electrolyzers, and electric vehicles, gasification, hydrogenation, and co-electrolyzers. The model is a freeware used in many countries globally