Experimental investigation of natural ventilation characteristics of a solar chimney coupled with earth-air heat exchanger (SCEAHE) system in summer and winter

The coupled effect of the solar chimney (SC) and earth-air heat exchanger (EAHE), as a pure passive system, is expected to generate natural ventilation with a cooling/heating potential. This study aimed to experimentally evaluate the natural ventilation characteristics of SCEAHE system in both summer and winter. The results showed that under the regulation of SCEAHE system, indoor air temperatures below 29 °C accounted for 78.6% of the total 168 h in summer, whereas indoor air temperatures above 5 °C accounted for 77.4% during the winter. The driving force for nocturnal ventilation was generated by the coupled effect of the thermal mass and subsoil in summer, whereas the same was generated by only the subsoil in winter. This shift in buoyancy forces ensured continuous nocturnal natural ventilation for an annual cycle. The continuous and periodic airflow rates varying from 56.5 to 291.5 m³/h, and from 90.9 to 388.8 m³/h were observed during the summer and winter, respectively. Therefore, the SCEAHE system was able to provide continuous natural ventilation, even under the cloudy weather condition. In addition, the average thermal efficiency of the system was 0.61 in the summer, while the average value was 0.86 in the winter.