# Improving School Transition Spaces Microclimate to Make Them Liveable in Warm Climates
## 1 Introduction
In this way, it is possible to achieve a thermal balance in a specific urban environment, reducing the absorbed solar radiation [11]. The use of materials characterized by a remarkably high reflectance reduces the solar radiation absorbed to a greater extent than conventional materials, being useful to reduce the temperature of certain spaces in cities, and therefore, reducing the UHI effect [12]. Different studies carried out on albedo deal with their ability in terms of air and surface thermal managing, but hardly anyone takes into account the users' thermal comfort perspective [13]. In courtyards, a specific microclimate is generated, with a thermal reduction compared to the outdoor temperature [14]. The analysis of the influence of albedo and vegetation as passive strategies in these spaces can help to clarify their relevance in buildings and cities [15; 16]. Additionally, the impact of vegetation on the courtyard microclimate is another important cooling strategy to counterbalance global radiation and high air temperature [17]. The tempering effect of vegetation is due to the evapotranspiration physical phenomenon, the blockage of solar radiation, and the reflection of the solar radiation due to its higher albedo compared to other materials [5]. The vegetation performs two particular functions in these systems: (a) intercepting sunlight before the building gets warm, which is an energy-saving instrument that controls solar radiation in the summer and avoids overheating and temperature fluctuations inside the buildings. Additionally, (b) decreasing wind speed [18]. The cool surfaces provided by the leaves can be effective in reducing the energy used for cooling and heating [19]. The vegetation acts as a cooling element due to evapotranspiration [20], a process based on the evaporation of water in the vegetation and surrounding soil [21]. This paper aims to shed light on the urban overheating phenomenon by analyzing thermal conditions in courtyards. The study focuses on the building envelope, analyzing the microclimatic impact of the coating materials. To this end, the effect of albedo and vegetation, and the resulted thermal differences within two case studies located in the city of Seville have been considered. The microclimatic evaluation has been performed through two different experimental setups applied in two free-running school buildings. Assessment of the thermal parameters in the outdoor environment and the courtyards, and building data related to the geometry, orientation and solar direct radiation would be previously studied to evaluate the courtyards' thermal tempering potential. Although the results obtained in this study are limited to the geometry of transitional spaces such as courtyards under climatic and radiation conditions defined by a precise location, the proposed method has several advantages: it is simple, fast and can be easily implemented in microclimate assessments of outdoor and semi-outdoor spaces. Furthermore, the main novelty of the study is to determine the influence of building envelope surface materials in these semi-outdoor spaces quantifying their impact as passive strategies through full-scale experiments.