Urban energy systems are the key elements of combating the climate crisis as the energy transition is crucial to curb greenhouse gas emissions in urban areas, one of the main drivers of climate change. As such, there is a great effort in Amsterdam to phase out natural gas use by 2040, and to become carbon neutral by 2050. It is a great challenge since the existing centralised energy systems are specifically built on the transportation and use of large amounts of fossil fuels while renewable energy has many limitations due to the volatility of its sources, lack of capacity for energy load and storage. Yet, since renewable energy sources are locally available everywhere, the establishment of decentralised renewable energy infrastructures based on local sources can help overcome these limitations. On this basis, this research explores the possibility of developing such systems through a case study in the historic centre of Amsterdam where many local challenges like urban monumentality pose risks for the energy transition. The research is structured around the use of Smart Urban Isle approach as a methodological tool to reveal local potentials for energy reduction, reuse and production, and to design energy concepts based on these potentials to reduce the reliance on external energy input. The results of the case study show that it is possible to cover the heat and cold demand with local sources and to cut almost half of the external energy input into the site without bringing any significant pressure onto the power grid. This outcome is highly promising as it proves that such local interventions can make great contributions to the energy transition process by significantly reducing the tension on the regional and national energy systems for the replacement of fossil fuels. As for the field of architecture and urban planning, the results implicate that the bioclimatic design principles, mixed-use of buildings and urban spaces, and small-scale and decentralised urban infrastructures based on the circular economy and self-sufficiency principles are crucial to achieve higher energy efficiencies and more local energy inputs.