This report aims to evaluate the potential of sharing energyregarding heat and cooling between buildings in a smalldecentralized energy system. A model of an energy substation wasdeveloped in IDA ICE Advanced level only system to create a timeefficient tool that is easy to handle for people in the industry.Three cases of building stocks with different heating and coolingdemands were modeled in the energy substation, both separately andcollectively, to investigate the differences in energy performanceas a result of energy recovery between buildings. The study also contained a sociotechnical aspect of thedecentralized energy system. Interviews were carried out to studyhow a mutual energy substation is implemented in reality and whatchallenges and opportunities the technology faces. An importantconclusion is that the future development for this new technologyis highly dependent on an increased cooperation between companiesin the industry.The simulations of the cases showed an improved energy performancefor the mutual energy substations in all three cases, sevenpercent improvement as most. The report concludes that there ispotential for an improved energy performance in a building stockwhen implementing a mutual energy substation since it enables theability to save energy through energy recovery. Furthermore, it isconcluded that a resembling heat and cooling demand within thebuilding stock increases the total energy performance of thesystem. An improved control system of the model is recommendedbefore deciding if and where it is beneficial to implement amutual energy substation.