The combination of high ambient temperatures and solar radiation in tropical climates causes thermal discomfort in buildings. Mechanical air-conditioning systems are used for cooling buildings, with high energy demands to operate and maintain these systems continuously over long periods of time over the year.

With the rapid increase in population and economic growth of countries in the tropical regions, it is becoming inevitable that passive and low energy strategies must be used as suitable alternatives for cooling. Earth-air heat exchanger (EAHX) is a subterranean ventilation system that explores soil temperature below the ground surface to pre-cool or pre-heat ventilation air, performance varies with climatic and soil condition of the area.

This research has determined the climatic and soil parameters affecting the thermal performance of EAHX for chosen locations in Nigeria. Thermal simulations have been carried out using Transient System Simulation Environment (TRNSYS) to evaluate the cooling energy gain and the reduction of ambient temperature extremes. The results show that the system can significantly improve comfort conditions and reduce building cooling loads.