# Thermal Comfort and Sustainability in University Classrooms: A Study in Mediterranean Climate Zones
## 1 Introduction
The assessment of thermal comfort in naturally ventilated versus air-conditioned university classrooms is key, especially in regions with variable climatic conditions, such as the Mediterranean. This analysis reveals significant differences in occupant satisfaction, adaptive behaviours and indoor environmental quality. Classrooms with natural ventilation tend to offer a more adaptive environment for occupants, allowing them to experience a wider range of thermal comfort due to their ability to adapt to changing environmental conditions [29]. For example, [PERSON] et al. noted that occupants in naturally ventilated environments can adjust to a greater diversity of microclimatic conditions, demonstrating remarkable thermal adaptability compared to air-conditioned spaces, where conditions are more controlled [30]. This flexibility is reinforced by the findings of [PERSON], who noted that students in naturally ventilated classrooms employed a variety of adaptive behaviours that improved their thermal comfort, especially during seasonal fluctuations typical of Mediterranean climates [31]. In addition, [PERSON] et al. emphasised that natural ventilation contributes to thermal comfort and indoor air quality, although it may be less effective in conditions of low air velocity or high outdoor temperatures [32]. In terms of energy efficiency, [PERSON] et al. indicated that indoor temperatures up to 26 \({}^{\circ}\)C do not compromise thermal comfort, which could help attempts to minimise cooling energy consumption in hot climates [33]. Similarly, [PERSON] et al. found that strategies such as cross-ventilation in naturally ventilated classrooms significantly improved thermal comfort during the warmer months, achieving optimal conditions in approximately 51% of the occupancy periods [34]. However, very few studies have analysed thermal comfort in air-conditioned classrooms in these regions, despite the growing relevance of these systems due to the increase in global temperatures and the extension of warm periods in this area, as already mentioned. In such work, it has been observed that refrigerated spaces offer a more stable thermal environment, which can be advantageous in meeting established comfort standards [2]. Thus, [PERSON] et al. concluded that these classrooms consistently remain within the defined comfort limits, which is not always the case in naturally ventilated classrooms during the highest summer temperatures [35]. Also, [PERSON] et al. noted that HVAC systems are effective in keeping indoor temperatures within comfortable ranges, which improves the learning environment [36]. In line with this, [PERSON] et al., in a study conducted in southern Spain, found that students preferred air conditioning when outdoor temperatures exceeded 25 \({}^{\circ}\)C [37]. Similarly, no research has been found that specifically analyses the influence of student position within these spaces as a function of mode of operation (AC or NV). This gap in the literature represents an opportunity to explore how factors such as proximity to windows, doors or air-conditioning vents affect the thermal experience of occupants. The lack of studies on this topic is particularly relevant, as positions within the classroom generate significant thermal gradients, which impact individual perceptions of comfort and the effectiveness of air-conditioning strategies in ensuring a thermally adequate environment. In this context, it is key to adopt a perspective that combines practical and sustainable solutions to improve thermal comfort in educational spaces, considering both the environmental characteristics and the specific needs of students. This involves not only optimising the design of buildings and taking advantage of passive strategies, such as natural ventilation, but also understanding how students perceive and adapt to thermal conditions. Ensuring a comfortable and healthy classroom environment not only promotes physical well-being but also improves concentration and academic performance.