Effects of Different Weather Conditions on the Performance of Earth-to-Air Heat Exchanger Systems

<p>In recent years, the earth-to-air heat exchanger (EAHE) system, which uses the heat capacity of soil to reduce the external air heat load, has attracted attention as an energy-saving system. Such underground systems are often adopted for large-scale buildings such as schools and hospitals. However, because the system has complicated heat transfer properties owing to its external air route, a universal method for predicting its performance in pre-cooling and heating has not yet been established. Furthermore, although various studies on the earth-to-air exchanger system based on actual surveys and numerical analysis are being conducted mainly in Japan, all verifications are limited to some regions, and the effect of different weather conditions on the earth-to-air exchanger system has not been clarified. In this study, we developed an analytical model of the EAHE system and analyzed it using a novel method (high-speed analysis) to predict the long-term system performance. By forecasting the annual performance in pre-cooling and heating as well as the dew condensation properties, we aim to clarify the effect of differences in weather conditions on the EAHE system by implementing annual performance predictions of pre-cooling and heating effects and dew condensation properties. The following results were obtained: (1) It was suggested that the possibility of dew condensation in Kitakyushu is higher than that in Akita City from spring to autumn. On the other hand, it was suggested that the possibility of dew condensation in Akita City is lower than that in Kitakyushu from January to June. (2) The average annual temperature in Akita City as well as the soil temperature were lower than those in Kitakyushu, and the soil temperature was also lower. This suggested that the cooling effect in summer in Akita City may be higher than that in Kitakyushu.</p>