With rising focus on integrating high shares of renewable energy into energy supply systems, the need to meet the viability of theses renewable sources becomes pressing. Apart from storing electricity in electro-chemical storage units, the concept of sector coupling could promise to provide the needed flexibility and storage capacities. A strong metric is needed to determine the viability and economic feasibility of different sector-coupled energy systems. This conference paper presents an empirical method to develop a list of key performance indicators (KPI), as a direct adaption of the KPI of energy system with a single energy vector is not always possible. The list was developed based on a stakeholder workshop within the H2020 research project E-Land. We propose the introduction of three new indicators for the evaluation of sector-coupled energy systems, namely degree of autonomy, levelized cost of energy and degree of sector coupling. A sector-coupled case study is evaluated to validate the performance of such new indicators while proving their utility to better assist decision-making.