Experimental study on natural ventilation using an earth-to-air heat exchanger combined with a solar chimney and its impact on the indoor thermal environment

The earth-to-air heat exchanger (EAHE) is a shallow geothermal energy technology capable of significantly reducing building energy consumption. When combined with a solar chimney (SC), a novel passive ventilation and cooling system is established in which fresh air is cooled and naturally drawn into the indoor space. This study investigates the effect of SC-EAHE system on the indoor thermal environment in regions characterized by hot summers and cold winters, and compares the building envelope performance with and without the system. Experimental results show that, compared to a reference chamber, the EAHE reduces air temperature by 3.2 ℃ in summer and increases it by 1.6 ℃ in winter, with corresponding air change rates ranging from 2.2ACH (air changes per hour) to 10.1 ACH in summer and 3.4ACH to 13.5ACH in winter. Relative to the ambient air, the indoor air temperature shows a maximum decrease of 5.9 ℃ in summer and a maximum increase of 15.5 ℃ in winter. The south-facing exterior wall and the roof receive the highest solar irradiation among all envelop surfaces. In summer, the average temperature of the interior surface of the southern wall is reduced by about 1.1 ℃, while the roof temperature remains unchanged. In winter, the average interior temperatures of the southern wall and roof increase by 1.5 ℃ and 1.7 ℃, respectively.