Trigeneration systems, which are currently used as an effective method for energy solution in integrated structures or settlements, are the systems that generate high potential heat depending on the waste source potential. Such integrated structures have fluctuating temperature and heat requirements depending on seasonal and building operational conditions. It has been seen that prioritizing the energy demand management of the systems provides significant gains in energy efficiency. In this study, efficiency analysis to be provided in the system according to the preference of heating and cooling demands in a trigeneration system is carried out according to thermo-economic principles. Conventional trigeneration system and modified system were examined comparatively based on demand management optimization on real field study data. In the analysis, it was seen that the modified system developed depending on demand management provides approximately 22.4% extra saving from the utilized heat for heating and cooling. It is aimed to emphasize significance effect of heat demand management on system efficiency in such systems. Additionally, a new index named “Sustainable Heat Management Index” is introduced to help facility managers deciding to operate their trigeneration system’s utilizing waste heat for heating or cooling system primarily.