An air conditioning method includes the steps of: dehumidifying an air stream to be provided to a building space by exposing the air stream to a liquid desiccant in a conditioner; diverting a portion of the air stream dehumidified in the conditioner to an air treatment unit acting as an evaporative chiller to that causes the portion of the dehumidified air stream to absorb water from a water source and thereby cool a heat transfer fluid, and providing the heat transfer fluid cooled in the air treatment unit to the conditioner to cool the air stream to be provided to the building space; and regenerating the liquid desiccant used in the conditioner.