In the context of climate change, there is increasing concern about the likelihood of overheating in hospitals. The aim of this paper is to investigate the heat stress exposure through the Wet Bulb Globe Temperature (WBGT) heat index in four different rooms of the 1st Internal Medicine Department of the American Hellenic Educational Progressive Association (AHEPA) hospital located in Thessaloniki, Greece. In hospital environments patients usually have restricted adaptive opportunity. Thus, the need for an indoor heat-safety metric is imperative. This study proposes thresholds of 24oC and 26oC to assess critical ward spaces as these are the initial warning points for nighttime thermal discomfort of healthy individuals in ‘normal’ environments. In this context, the internal temperatures measured in the patients’ rooms were plotted against the indoor WBGT thresholds for a low wind velocity of 0.1m/sec. Between the 13th and the 22th of June 2017 the most extreme temperatures were recorded in room 3, while the mildest conditions occurred in room 1. WBGT ranged between 19⁰C and 25.46⁰C. The recorded WBGT in three rooms exceeded the threshold of 24oC for approximately one-third of the time, while in one room it was marginally below the proposed threshold
