1 A parametric analysis of the cooling performance of vertical earth-air heat exchanger in a subtropical climate S. F. Ahmed a,d* , M. M. K. Khan b , M. T. O. Amanullah c , M. G. Rasul d,* and N. M. S. Hassan e a Science and Math Program, Asian University for Women, Chattogram-4000, Bangladesh b College of Engineering and Aviation, Central Queensland University, 120 Spencer St., Melbourne, VIC 3000, Australia. c School of Engineering, Deakin University, Geelong, Victoria-3220, Australia d College of Engineering and Aviation, Central Queensland University, Rockhampton, QLD 4702, Australia e College of Engineering and Aviation, Central Queensland University, Cairns, QLD 4870, Australia *Corresponding author email: shams.ahmed@auw.edu.bd, shams.f.ahmed@gmail.com (S. F. Ahmed). m.rasul@cqu.edu.au (M. G. Rasul), Tel: +61 402 431 669. Abstract Nearly 30% of global energy is consumed in buildings for heating and cooling. Many researches have been undertaken at finding novel techniques to reduce buildings’ energy consumption without using any conventional mechanical devices. Earth-air heat exchanger (EAHE) is such a passive cooling technique that is seen to significantly reduce energy consumption. This paper investigates the cooling performance of a vertical EAHE for a subtropical climatic zone through a parametric analysis. A thermal transient model for the vertical EAHE has been developed using ANSYS Fluent to analyze the parametric study. The influence of the key parameters: air velocity, thickness, diameter, depth, length, and material of the pipes on the EAHE cooling performance has been conducted and presented here. This parametric study is viewed as new in a subtropical climate since no such study is found in the literature and its outcome will provide a deeper understanding of the passive cooling system. The cooling performance is considerably affected by pipe diameter, air velocity, and pipe length while no noticeable impact is found for pipe material. The optimal performance contributed to reducing the outlet air temperature up to 8.21 o C. Keywords: Ground heat exchanger, heat exchanger model, EAHE performance, parametric study, building energy consumption. Nomenclature , p air C Specific heat of the air (kJ/kg K) , p wa C Specific heat of water (kJ/kg K) C I Compressor current (A) ef I Evaporative fan current (A) P I Pump current (A) k Materials’ thermal conductivity wa m Rate of mass flow of water (kg/s) con Q Rejected heat from the ground in cooling mode (kW) cl Q Cooling load of the space (kW) , air i T Average inlet air temperature ( o C) , air o T Average outlet air temperature ( o C)