Waste production is increasing every day as a consequence of human activities; thus, its valorization is becoming more important. For this purpose, the usage of wastes as biofuels is one of the most important aspects of sustainable strategies. This is the case of the main waste generated in brewing industries: brewers’ spent grain (BSG). In this sector, microbreweries are not able to properly manage the wastes that they generate due to lack of space. Consequently, the transformation of BSG to a high-quality biofuel might be an interesting option for this kind of small industry. In this work, we carried out a physical-energy characterization of BSG, as well as pellets from this waste. The initial characterization showed slightly unfavorable results concerning N and ash, with values of 3.76% and 3.37% db, respectively. Nevertheless, the physical characterization of the pellets was very good, with acceptable bulk density (662.96 kg·m⁻³ wb) and low heating value (LHV; 17.65 MJ·kg⁻¹ wb), among others. This situation is very favorable for any of the intended uses (for energy use or animal feed, among others).

Thermal comfort in educational buildings affects not only the well-being of students but also their academic performance. Over time, various methods have been developed to assess it. However, none of them takes into account the adaptation of students of different ages, which is an important issue. In recent years, the study of thermal comfort has become very important due to energy-saving measures and ventilation protocols to combat the spread of the SARS-CoV-2 coronavirus. Therefore, it is necessary to gather all the information to guide future research. Thus, this paper presents a comprehensive review of field studies on thermal comfort in classrooms at different educational levels. The focus is on those conducted during the global pandemic of COVID-19. It has been observed that students from climates with a higher degree of variation have shown a better adaptation. Children also tended to feel less affected by changing temperatures. High school and university students showed a greater range of dissatisfaction with heat than with cold. The adaptive approach is more suitable for recognising the comfort needs of all age groups. However, by using this approach together with the Fanger method, more reliable results have been reported. In most of the studies, comfort levels were found to be lower than those indicated by the standards, highlighting the need for guidelines adapted to the thermal comfort conditions of all students. Finally, the various natural ventilation measures to avoid COVID-19 infection have led to a decrease in comfort levels, especially in winter.

Thermal comfort in educational environments affects not only students’ well-being but also their concentration and academic performance. In the context of climate change, university classrooms in Mediterranean climates face particular challenges due to higher and more variable temperatures. This study evaluates thermal comfort in classrooms in southern Portugal, comparing natural ventilation (NV) and air-conditioning (AC) modes. Through environmental measurements and student surveys, thermal perceptions, preferences and factors such as position within the classroom were analysed. The results reveal that NV classrooms offer sustainable benefits, but their effectiveness decreases when outside temperatures exceed 28 °C, increasing thermal discomfort. In contrast, AC classrooms maintain more stable and comfortable conditions, although they have thermal gradients that affect specific zones, such as areas near windows or air vents. This study highlights the need for hybrid strategies that prioritise NV in moderate temperatures and use AC as a support in extreme conditions. Furthermore, it underlines the importance of appropriate architectural design and specific adaptive models for Mediterranean climates, balancing thermal comfort and energy efficiency.

Academic performance is the level of achievement that students reach in their educational activities. It is influenced by several factors that should be analysed and prioritised, especially in engineering courses, characterised by their difficulty and low success rates compared to other careers. This paper analyses the impact of these factors on academic performance during exams in a technical college in southwestern Spain, with a particular focus on environmental conditions, identified as a relevant and independent variable. The results show a significant connection between thermal comfort and academic performance. Temperatures within the comfort range (23–26 °C) improved students’ satisfaction with exams. In contrast, those who experienced thermal discomfort pointed to environmental conditions as the main obstacle to their performance, overcoming factors such as prior preparation and coincidence of exams. These findings underline the importance of optimising the classroom’s thermal environment through strategies that promote a more favourable learning space, improving both students’ well-being and their academic performance.

The corn crop is one of the most important crops worldwide. However, the management of the residues generated is not efficient enough, which diminishes the competitiveness of this crop. An interesting option for the valorization of these wastes is their thermal use. In order to make the management of this residue as much efficient as possible, it is vital to know the different processes related to a corn harvest, and try to adapt the use of this waste depending on its characteristics. Thus, in this work, and on the basis of a conventional corn harvest, a differentiated analysis of the residue generated was carried out, including its characterization and assessing its behavior during pyrolysis and combustion. The results pointed out the importance of collecting residue immediately after its generation and avoiding its contact with the soil as this factor tends to worsen its thermal properties and ash content. Concerning the selective collection, it is highly advisable if the subsequent thermal use is going to be a pyrolytic process. In the case of combustion, even though the samples that contain corn stalk showed better combustion properties, this improvement did not outweigh the adverse effects related to the increase in ash content, especially for its pelletizing.

After the COVID-19 lockdown, the health authorities established strict protocols for ventilating indoor spaces and reducing contagion. Although the control of the disease allowed these measures to be relaxed, indoor air quality (IAQ) and natural ventilation (NV) are still essential. However, in certain climatic conditions, this can affect the thermal comfort of the occupants. This situation is relevant in educational buildings, where thermal discomfort can influence students’ academic performance, especially during critical periods such as exams. In this context, this article explores how different NV strategies, both during and after the pandemic, affect the thermal comfort of students at a university in a Mediterranean climate zone. The analyses revealed that, despite the low temperatures and strict ventilation protocols due to COVID-19, thermal comfort during winter was higher than in spring and summer. These results led to an investigation into which variables could explain this phenomenon, detecting that the choice of clothing was crucial to achieving adequate comfort conditions. Regarding IAQ, ventilation was sufficient, even excessive, in some cases, especially during mandatory measures. In conclusion, it would be beneficial to establish ventilation protocols adapted to each environment and to advise students on individual strategies to improve their thermal comfort.