applied sciences Article  
Use of \"Glass Curtain\" Systems to Improve the Energy Efficiency and Thermal Comfort of Dwellings in a Warm Semi-Arid Mediterranean Climate [PERSON]*\({}^{\text{\textcircled{\textcircled{\textcircled{\textcircled{\textcircled{\textcircled{\textcircled{\textcircled{\text{\textcircled{\text{\text{\text{\text{\text{\text{\text{\text{\text{ \text  
radiant temperature (MRT), which influences the operating temperature distribution and indoor thermal comfort [22; 23; 24]. This influence is especially important in high sunlight regions throughout the year, and the operating temperature is taken to be the mean of the dry-bulb air temperature and the radiant temperature for indoor air velocities under 0.2 m/s [25]. On the other hand, the advantages of natural ventilation in summer in terms of dissipating excess heat have also been demonstrated [26; 27; 28; 29; 30]. Therefore, the residential architecture of coastal cities in Spain has usually had large porches or terraces that protected the windows from the sun. Traditional dwellings have also been characterised by natural cross-ventilation [31]. In recent decades, rising house prices in cities and tourist towns has led to the glazing of many balconies to gain usable space in houses [32; 33]. This is why the influence of balcony glazing on the energy efficiency and thermal comfort of dwellings in this climate was studied in previous research [34]. This study showed that glazed terraces improve the indoor thermal comfort and energy efficiency of homes if they are kept separately from the other parts of the dwelling in winter [35; 36; 37] and if they are open in summer. It also showed that terraces with more glazing and more openness also improve the thermal performance of the house. This study led to the conclusion that the glazing of terraces increases the greenhouse effect in the house and helps to heat it for free in winter [38; 39; 40], although it is also essential to dissipate excess heat with natural ventilation in summer [41; 42; 43]. However, the current standards and official software [3; 4; 44] do not include either the possibility of using daytime natural cross-ventilation or glazed terraces with retractable glazing that is kept closed in winter and opened in summer or other passive solutions. Contrary to these standard limitations, this work argues that the characteristics of the BShs climate make it possible to propose bioclimatic solutions based on more permeable and flexible enclosures, adaptable to the different seasons of the year, and more in keeping with traditional Mediterranean architecture and lifestyle. This work suggests using glazed terraces with retractable glazing to heat dwellings in winter and promotes the use of natural ventilation to cool dwellings in the warmer months [45; 46; 47; 48; 49; 50]. For this purpose, it is proposed to use balcony frameless retractable glazing systems known as \"glass curtain\" systems. Such a system consists of an enclosure of glass sheets held in place by two small longitudinal metal profiles at the ceiling and floor. These glass sheets can be completely folded over each other, leaving the terrace open. \"Glass curtain\" systems allow the maximum glass area and the largest possible aperture. Therefore, they can capture the maximum amount of heat energy from solar radiation in winter, and they can be completely opened in summer, dissipating the accumulated excess heat inside the home and avoiding the greenhouse effect. Based on the results of these previous works, this research analyses the influence on energy efficiency and indoor thermal comfort of using glazed terraces with \"glass curtain\" systems. To this end, it studies and comparatively analyses the current thermal performance of the dwelling with and without a \"glass curtain\" system via on-site measurements. After that, the study evaluates the influence of modifying several design parameters of the glazed terrace and the \"glass curtain\" system using computer simulations to optimise the thermal performance of dwellings.