Using renewable energy for heating and cooling applications covers the increasing demand of energy sources. In the present study, numerical analysis is used to study 9 closed-loop geothermal air pipe system cases during summer and winter with different pipe geometry of diameters of 0.17, 0.35, and 0.65 meters and total pipe lengths of 47, 64 & 87 meters for air conditioning application. The conditioned air is then supplied to a room of Length 3m x Width 3m x Height 3m. The numerical model is combined with a 1 m length solar chimney of 45ᵒ inclination angle. Also, an experiment was conducted in Damanhur city, Beheira Governorate, Egypt, providing conditioned air to a room of L 2m x W 2m x H 2m via a 5 m long, 5.3 mm thick geothermal PVC air pipe of 2 inches in diameter. The pipe was buried at 2 m depth and was supported by the solar chimney during winter to provide natural draft force inside the closed-loop system and to support the heating process. On the other hand, the closed loop contains a driving fan to provide circulation during summer. The results of the numerical model prove that the numerical analysis showed the highest level of air conditioning temperature difference close to 5 ᵒC for the case of 0.65 m diameter pipe, and 87 m total length. The validation of the numerical model was carried out using experimental results.