Air conditioning apparatus

Air conditioning apparatus comprising a plurality of air outlets each of which is operable to deliver air circulated thereto to a space to be conditioned, means for dehumidifying air, means for circulating dehumidified air to said air outlets at a rate per unit of area in the spaces served by said air outlets which varies between a predetermined minimum rate greater than zero and a maximum rate, the maximum rate being substantially less than that which would be required to maintain the design temperature in each of the spaces at the maximum design cooling load with air supplied to the spaces at a dry bulb temperature of 55.degree. F., means operable to control its moisture content and temperature so that the dehumidified air is incapable, at the rate at which it is required for humidity control, of maintaining the desired space temperature at the maximum design cooling load, a plurality of means positioned for heat transfer to or from spaces to be conditioned by the apparatus or to or from air delivered to spaces to be conditioned by the apparatus, and means operable to control the rate at which dehumidified air is delivered by said air outlets to the spaces they serve to one not less than the predetermined minimum rate and higher than that minimum when required to maintain a monitored condition of the space within control limits.