Air conditioning is one of the essential techniques employed to provide human comfort, as well as to generate favourable conditions for industrial, agricultural and biological processes. In this paper, the means for simulating the principal air-conditioning processes are discussed. Interactive computer routines (in Basic language) have been composed for (i) estimating the relevant properties of atmospheric air (i.e. the psychrometric properties), and (ii) predicting the behaviour of air when undergoing constant-pressure mixing, heating, cooling, humidification and dehumidification processes. The developed programs are listed. Samples of the predictions are also presented. The computer programs should help in obtaining the necessary data when designing the hardware, and selecting the appropriate control equipment, for an air-conditioning system in an envisaged application. © 1990.