UNIVERSAL THERMAL CLIMATE INDEX (UTCI): A CHALLENGE FOR THE INDOOR THERMAL ENVIRONMENT ASSESSMENT Francesca Romana d’AMBROSIO ALFANO – e-mail: fdambrosio@unisa.it DIIN - Dipartimento di Ingegneria Industriale, Università di Salerno Via Ponte Don Melillo, 84084 Fisciano (Salerno), Italy Tel. +39 089 964107 – Fax +39 089 964037 Boris Igor PALELLA – e-mail: palella@unina.it DETEC - Dipartimento di Energetica, Termofluidodinamica Applicata e Condizionamenti Am- bientali, Università degli Studi di Napoli Federico II Piazzale Vincenzo Tecchio 80, 80125 Napoli, Italy. Giuseppe RICCIO – e-mail: riccio@unina.it DETEC - Dipartimento di Energetica, Termofluidodinamica Applicata e Condizionamenti Am- bientali, Università degli Studi di Napoli Federico II Piazzale Vincenzo Tecchio 80, 80125 Napoli, Italy. Abstract. Bioclimatic indices, primarily devoted to the weather forecasts, in some cas- es are also used for the indoor thermal environment assessment with a consequent underes- timation of both comfort and stress situations. The reason are: a) an empirical formulation; b) the need to collapse in few measurements and calculations the complexity of the physiologi- cal response of the human body which is affected by six parameters (air temperature, air ve- locity, relative humidity, mean radiant temperature, metabolic rate and clothing thermal insu- lation); c) they are usually validated under specific climatic conditions. On this point of view, the Universal Thermal Climate Index (UTCI), formulated in 2009, exhib- its a very innovative approach because: a) it is based on the well-known and most advanced Fiala’s thermoregulation model; b) it takes into account the whole of the parameters affecting the thermal sensation; c) it can be used in a wide range of climatic conditions (from the cold to the hot). On the base of so interesting peculiarities this paper deals with a comparison between the assessment carried out according to the methods suggested by ISO 7730 and UTCI index. Obtained results show that UTCI index can only provide a qualitative assessment of the thermal sensation in moderate environments. Keywords: Thermal Environment Assessment, Indices, Comfort 1. INTRODUCTION Due to the trivial effects on the health and the productivity, the thermal sensation evalua- tion is a crucial matter of both the ergonomics of the thermal environment and the human bi- ometeorology (Parsons, 2003; REHVA, 2006). It is common knowledge that the thermal sen- sation is affected by the subject-environment heat transfer phenomena that are strictly re- lated to four environmental quantities (the air temperature, the mean radiant temperature, the