Rational use of energy and its associated greenhouse gas emissions has become a key issue for a sustainable
environment and economy. A substantial amount of energy is consumed by today’s buildings which
are accountable for about 40% of the global energy consumption. There are on-going researches in order
to overcome these and find new techniques through energy efficient measures. Passive air cooling of
earth pipe cooling technique is one of those which can save energy in buildings with no greenhouse
gas emissions. The performance of the earth pipe cooling system is mainly affected by the parameters,
namely air velocity, pipe length, pipe diameter, pipe material, and pipe depth. This paper investigates
the impact of these parameters on thermal performance of the horizontal earth pipe cooling system in
a hot humid subtropical climate at Rockhampton, Australia. For the parametric investigation, a thermal
model was developed for the horizontal earth pipe cooling system using the simulation program, FLUENT
15.0. Results showed a significant effect for air velocity, pipe length, and pipe diameter on the earth pipe
cooling performance, where the pipe length dominated the other parameters.