The project concerns the energy upgrade of the “Chalkiopoulio” Closed Gymnasium of the Municipality of Lamias and includes the following interventions:1. Upgrading of automatic control systems of air conditioning heating systems, as well as lighting, at the level of the Central Management System, while using saving technologies.2. Convert diaphragms in mixing boxes to electric motors and upgrade of valve triodes in Central Air Conditioning Units (CCI) to progressive operation.3. Replacement of all the luminaires of the stadium with new LED lighting, high energy efficiency.4. Installation of photovoltaic frames with a total nominal capacity of 125 kW, for self-production with net metering.5. Replacement of the damaged insulation of the roof surface of approximately 800 sq.m. Replacement of the old, damaged and out-of-function solar collector system with a total surface area of 72 sq.m. with new, new pipes and selective collectors. In this context, all 2 old single double-energy water heaters are replaced with new equivalent capacity.7. Replacement of oil burners with corresponding gas burners, to exploit the highest efficiency and the economy of the new fuel. Includes infrastructure (pipes, safety devices) for natural gas.