In the present research, a yearly performance of a gas turbine unit and the unit with the added inlet air cooling technologies (IACTs) was investigated in terms of performance and output power using TRNSYS software. The existing system was retrofitted with five different IACTs, namely Config. A: existing system integrated with an evaporative media, Config. B: existing system integrated with a fogging unit, Config. C: existing system integrated with a mechanical chiller, Config. D: existing system integrated with an absorption chiller, and Config. E: existing system integrated with a thermal energy storage. The configurations were examined to determine the most proper configuration. The study revealed that Config. C was superior and was the optimal configuration for the gas turbine unit and it was recommended for the existing system. The study showed that Config. C was capable of enhancing the yearly output power with about 10.62%. After determining the proper configuration, a method benefiting a passive energy technology of heat pipe structure was also proposed. In the proposed method, a water-to-air heat pipe heat exchanger (HPHX) consisting of single heat pipe tubes was planned to be added to Config. C as a pre-cooling equipment. To this end, the mathematical performance of the water-to-air HPHX was derived to be defined in TRNSYS studio. It was shown that a considerable amount of energy could be obtained after adding the water-to-air HPHX to Config. C. The exergy analysis also proved that application of IACT improves the exergy efficiency of the whole system. Keywords Gas turbine units • Inlet air cooling technologies (IACT) • Output power • Performance • TRNSYS List of symbols A Heat transfer area (m 2) a Tube distance in a row in Eq. (39) (mm) b Distance between the tubes in two successive rows in Eq. (39) (mm) bbl Barrel of oil C Heat capacity (J/s K) C pa Specific heat of air at constant pressure (kJ/ kg K) C pg Specific heat of turbine outlet gases at constant pressure (kJ/kg K) C 1 Constant in Eq. (21) (0.535) * M. Ahmadzadehtalatapeh