During recent years livestock producers have been requesting design assistance for subterranean heat exchangers to preheat and precool ventilation air. Very little quantitative design information is available to permit the specification of a subterranean system that would perform with optimal economic effectiveness. The objective of this study was to determine design guidelines for a subterranean tubing system to preheat winter ventilation air for swine farrowing and nursery operations in Ohio. Ventilation rates, pressure drops and heat transfer parameters, as well as the economic/practicality of such a system is determined.