In the design of air conditioning systems, introducing outdoor air is essential in maintaining a good indoor environmental air quality that helps building occupants feel stimulated and comfortable. In hot and humid weathers the fresh air cooling load may reach up to 50% of the building cooling load. Since air-conditioning equipment are the major energy consumers in buildings, reducing the Fresh air cooling energy demand forms a major challenge for engineers designing green and energy efficient buildings. The aim of this paper is to provide a comparative study for the energy performance of four different central fresh air treatment plant arrangements. The first arrangement considers the widely used tradition system of using a cooling coil to cool and dehumidify outside air to a low temperature followed by a heating coil to maintain the required supply temperature at the plant outlet. In the second arrangement air is divided in two streams, one that passes through a cooling coil while the other bypasses the coil; the two streams are then mixed to achieve dehumidification requirements. Combined air stream passes through a heating coil to maintain a fixed supply temperature at the plant outlet. A horseshoe heat pipe configuration is used in the third arrangement as a mean for precooling air entering as well as reheating air leaving the plant; in this arrangement a cooling coil is used to dehumidify outside air. In the fourth arrangement similar to arrangement 2, air is divided into two streams the first passes through the cooling coil and the second through an enthalpy wheel, then the streams are mixed and reheat is achieved through a heating coil. Doha, Qatar, weather condition is considered the basis for this study since it is classified as having hot and humid summer weather. All plant arrangements are simulated to have a leaving condition of 18°C (64.4 °F) and 9.5g/kg (0.0095 lb/lb) of air moisture content. The moisture content level is selected to be equivalent to a comfort indoor condition of 24°C (75.2 °F), 55% relative humidity. The fourth arrangement showed the best result in terms of the Peak cooling load, Peak heating load and total cooling energy when compared to the other three arrangements. Utilizing arrangement four in designing fresh air treatment plant may reduce the plant cooling energy load by 22% and the reheating energy load by 80% compared to traditional systems.