LAUSR

Abstract Generally, ventilation with outdoor air is used to directly remove heat in the top zone of large-space buildings to conserve energy. However, this will increase the latent cooling load because a large amount of humidity can be introduced to the interior when the outdoor air is humid. Therefore, a new method that incorporates a natural cooling water system in the top zone and does not introduce moisture is proposed in this study. The cooling tower as the source of natural cooling water and dry fan coil units (FCUs) as the terminal of removing heat were selected as an example of this new method. In order to analyze the energy saving potential of the new method, 9 cases involving different heat source distributions and cities were simulated by CFD, and 3 more cases with the traditional method were discussed. The results show that the traditional method increases the system energy consumption when the outdoor air humidity is high, and the biggest growth rate is 57.4%. But, the new method can be applied in different cities and in different heat source distributions, and can achieve a considerably high energy saving rate, ranging from 5.2% to 21.4%. The energy saving rate increases as the heat source ratio between the bottom zone and top zone decreases, because more heat can be removed by the dry FCUs. The energy saving rate varies by city, due to the different cooling water temperature. This new method will help guide the design of HVAC systems in large-space buildings.