The Center of Gravity Foundation Hall for the Bodhi Mandala Zen Center serves as the primary teaching and meditation hall for the existing Zen Buddhist Compound. It is located in a high mountain river valley in Northern New Mexico with abundant geothermal activity below the site. Conceptually, the project embraces oppositions; intersecting two embracing boxes - one of heaviness (rammed earth) and the other of lightness (polycarbonate on timberstrand) to define the transition from exterior to interior, and form the interior volume of the hall. The light translucent West side "glows" with light as the sun sets over the mountains. The East side cradles the space with thick earthen walls, partially containing the 'light' box. A folded, stealth like metal roof plane hovers over the space supported by glulam beams and purlins. Environmentally, the project operates at several different levels. The heating and cooling is both passive and active. Passively, the thick compressed earth walls act as thermal composites, keeping unwanted summer heat out during the day and re-radiating at night. In the winter the mass of the 26-inch thick earth walls and multil-layer polycarbonate walls limit thermal transfer. Cantilevered roof edges, up to 14 feet deep, block summer sun and allow the lower winter sun angle to radiate through the polycarbonate wall. Cooling works effectively via cross ventilation by opening the 36 feet of sliding panels to the east and the entry doors to the west, capturing natural prevailing breezes. Heat is generated actively during the winter by geothermal water that is captured on the site, passed through a heat exchanger, and radiated along the building's interior perimeter.