The effects of air-intake format of forced-air-cooled equipment on the efficiency of air conditioning systems are studied. A modern data center features a large number of information-processing devices to provide telecommunication services. These devices generate considerable heat, and the equipment that houses these devices often employs "forced air cooling" in which a cooling effect is achieved by sucking in large amounts of room air. An air conditioning system used for a machine room filled with such equipment therefore requires high fan driving power resulting in significantly low air conditioning efficiency. In this study, we first performed mockup-based experiments to obtain a quantitative understanding of how different air-intake formats for equipment affect the temperature at various room locations such as equipment intake. We then created a model for predicting the temperature at various locations, and on the basis of this model, we analyzed the factors affecting intake temperature and examined how intake temperature affects air conditioning efficiency. It was found that placing air inlets in the lower 1/3 portion of forced-air-cooled equipment could prevent the equipment from reabsorbing the hot air that it blows out and therefore improve air conditioning efficiency.