Outdoor-air design conditions relating to the capacity of air-conditioning systems

In this paper we present work involving the processing of climatic data relating to some Italian cities, taken from a set of data known as European ‘test reference year’ (TRY). We aim to make a critical comparison of the thermohygrometric conditions of outdoor air in the summer season thus obtained with those design conditions as laid down by Italian regulations (UNI 10339) and with those recently suggested by ASHRAE. Subsequently, and with reference to some traditional and recent applications in the field of air-conditioning, we report on how performance differs according to outdoor summer thermohygrometric design conditions, such as those indicated by UNI 10339, by ASHRAE and by the processing of TRY data. Finally, we discuss the optimal choice of design conditions according to the type of application.