Abstract: An underground air conditioning apparatus for underground cooling outside air directed into a space comprising an open-air inlet for admitting outside air including air quality control apparatus including an above ground intake and a below ground outlet manifold, a blower for creating positive air pressure, a well means for providing an enlarged conduit for conducting the admitted air below the ground surface to a heat exchanger apparatus positioned underground and surrounded by soil segment, earth-embedded conduit means for exchanging thermal energy between the admitted air and the earth said earth conduit, extending underground between the well means and the space including a plurality of open-air tubes arranged in a tier in a common plane buried in the earth having an inlet end and an outlet end.