Technological design of Positive Energy Districts: an easy-to-use tool for the Southern Italy area

Positive Energy Districts (PEDs) represent a promising approach for future energy systems aimed at achieving decarbonization goals, particularly with respect to carbon neutrality through the integration of renewable energy source-based plants at the district level. In order to promote the implementation of PEDs in the Southern Italy area, this study presents an easy-to-use tool designed to assist in preliminary sizing of the user-selected plant configuration. To ensure real applicability, the tool requires input data on district-level energy demand for space and process heating and cooling, electricity and domestic hot water on an hourly basis for a full year. The user can also select the location from various provinces in Southern Italy, from which real availability of renewable sources is considered. Additionally, plant configuration can be defined by choosing among a variety of renewable energy source-based plants, including solar collectors, wind turbines, photovoltaic panels, combined heat and power systems and electric heat pumps. Conventional backup systems are considered to cover unmet energy demand. The operation of all energy conversion systems is modelled by combining location-based renewable resource data with corresponding performance characteristics of plants. The operating priorities of each configuration are defined according to the technical constraints of the respective systems, while the sizing logic is designed to meet the associated district energy demand. Overall, nineteen different configurations can be simulated. The tool has been assessed using data from a district located in Benevento, including residential and office buildings. Three different plant configurations were simulated, two of which comply with the PED targets, namely annual renewable energy surplus and carbon neutrality. However, the results indicate that the plant configurations are not optimally sized, as more than 50% of the generated energy is frequently exported out of the district. This oversizing issue will be addressed by integrating thermal and electrical energy storage systems and by expanding the range of available sizes for each technology.