Energy, which is a part of our daily needs, is indispensable for our lives. Institutions and businesses play a huge role in making a country’s economy sustainable and meeting the needs of its citizens, besides profit making. It has a very important place in human health for the continuation of economic sustainability. For this reason, hospitals, which are health organizations, are necessary for people to maintain their health. In this context, it is vital to provide energy efficiently and sustainably in these hospital institutions that need to provide service twenty-four a day, seven days a week. The application of trigeneration systems, heating, cooling, and power, in hospitals to ensure energy efficiency discussed in this regard, seems to be able to solve the energy crisis. With this, the study aims to identify the most important factor by determining the factors affecting the feasibility of trigeneration systems to achieve energy efficiency in hospitals using the DEMATEL method, one of the multi-criteria decision-making methods. The most important criterion has been determined as the type of energy that affects the feasibility of trigeneration systems. The study finds that the type of energy used is very important to maximize the performance of trigeneration systems in hospital institutions. Thence, it is recommended that the hospitals where the system will be implemented should focus on research and development studies to search for energy sources that will have the lowest cost and highest output.