Thermal perception and occupant adaptive characteristics in naturally ventilated classrooms in different tropical climate seasons: A case study in Sri Lanka

Studying the thermal environment in classrooms is essential due to its impact on students' health, teaching, learning, and productivity. In the Nigerian context, there is a general lack of thermal comfort studies, and none specifically relate to secondary school settings. This study aims to investigate students' perceptions of the indoor thermal environment and to determine the optimum temperature in naturally ventilated classrooms in the tropical savanna climate. Field investigations were conducted in free-running classrooms in Abuja to evaluate occupants' thermal comfort and perceptions. The study involves 901 pupils from 21 classrooms. Data were obtained through physical measurements of thermal comfort variables and a questionnaire survey on occupants' perceptions of the indoor thermal environment. The objective assessment indicated that 86% of the classrooms were inconsistent with the ASHRAE standard–55. Although 60% of the pupils were satisfied with their thermal environment, 78% preferred a cooler than neutral temperature. The result revealed a comfort temperature of 28.9 oC. The results extend the literature on thermal comfort in classrooms to the tropical savannah climate of the west African sub-region, which has received little attention in earlier research. The findings provide foundation data for developing a comfort standard for classrooms in the zone.

Thermal comfort in university classrooms: An experimental study in the tropics

Space Design for Thermal Comfort and Energy Efficiency in Summer

On the potential of demand-controlled ventilation system to enhance indoor air quality and thermal condition in Australian school classrooms

This survey of thermal comfort in classrooms aimed to define empirically the preferred temperatures, neutral temperatures and acceptable temperature ranges for Australian school children, and to compare them with findings from adult populations. The survey was conducted in a mixture of air-conditioned, evaporative-cooled and naturally ventilated classrooms in nine schools located in three distinct subtropical climate zones during the summer of 2013. A total of 2850 questionnaires were collected from both primary (grade) and secondary (high) schools. An indoor operative temperature of about 22.5°C was found to be the students’ neutral and preferred temperature, which is generally cooler than expected for adults under the same thermal environmental conditions. Despite the lower-than-expected neutrality, the school children demonstrated considerable adaptability to indoor temperature variations, with one thermal sensation unit equating to approximately 4°C operative temperature. Working on the industry-accepted assumption that an acceptable range of indoor operative temperatures corresponds to group mean thermal sensations of −0.85 through to +0.85, the present analysis indicates an acceptable summertime range for Australian students from 19.5 to 26.6°C. The analyses also revealed between-school differences in thermal sensitivity, with students in locations exposed to wider weather variations showing greater thermal adaptability than those in more equable weather districts.

In Malaysia, students spend up to 33% of their day in classrooms and school buildings. Previous research had shown that thermal comfort conditions in educational buildings can stimulate student productivity. This study aimed to preliminary investigate the relationship between thermal sensation and student performance in the classroom. Data collection was conducted in a selected classroom at a secondary school in Segamat, Johor. All data were collected for three days. Physical measurement data were taken using thermal comfort equipment, KIMO AMI 310 for indoor measurement (air temperature, mean radiant temperature, air velocity, relative humidity), and TSI VelociCalc for outdoor measurement (air temperature, relative humidity). The thermal comfort satisfaction questionnaire was distributed to 36 students in the classroom. The learning performance was assessed through a simple reaction test and digit span test based on the WHO Neurobehavioral Core Test Battery (NCTB) method. The results of the thermal comfort satisfaction questionnaire clearly showed that the lower the fan speed, the more students preferred the cooler option. Furthermore, students performed better when the fan speed was increased. Based on the correlation analysis, it can be concluded that the learning performance and thermal preference vote (TPV) are positively correlated. As a result, students tend to get higher scores when they feel cooler. This study provides important preliminary information on classroom conditions in secondary schools in Malaysia and provides a better understanding of the relationship between thermal perception and student learning performance in the classroom.

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.

The significance of comprehending the thermal comfort perceptions linked to air conditioner usage in the morning and afternoon is underscored by the energy consumption in the building industry. Accurately identifying these impressions is essential for maximising air conditioner utilisation in accordance with daily weather conditions. It is crucial to ensure that every hour of the day, regardless of whether it is morning, noon, or afternoon, meets optimal comfort levels in extremely hot regions. Additionally, it is important to measure the energy consumption required to achieve these comfort levels. There is a dearth of research that takes into account both energy usage and thermal comfort in classrooms, as well as a distinct framework to assess these parameters across different buildings for the sake of comparison. The objective of this study is to assess and compare the thermal comfort levels in classrooms over two time periods, specifically from 08:00 to 12:00 and from 13:00 to 15:00, in a humid tropical climate during the peak of summer. Additionally, the study attempts to establish the energy consumption necessary to attain these desired comfort levels.

Achieving adequate thermal comfort in classrooms in hot cities in southern Mexico is challenging. A heterogeneous distribution of air conditioning flow leads to thermal discomfort, affecting occupants’ academic performance and increasing energy consumption. This study evaluates the thermal comfort of occupants in an air conditioned classroom using computational fluid dynamics. We determined the effects of variations in air conditioning operating parameters (supply angle, velocity, and temperature) on PMV and modified PMV indices. An operating configuration of 60°, 3 m/s, and 22 °C ensures that thermal comfort remains within regulations while optimizing energy consumption, in contrast to the original PMV model. Using the modified PMV model, the values are 0.38 for students and 0.31 for the teacher, with percentages of dissatisfied individuals of 10% and 7.7%, respectively. This study demonstrates the importance of analyzing air conditioning operating parameters to enhance thermal comfort while reducing energy consumption.

In classrooms, several variables may affect students’ thermal comfort, and hence health, well-being, and learning performance. In particular, the type of learning activity may play a role in students’ thermal comfort. However, most of the previous research has mainly investigated the thermal comfort of students in ordinary classrooms, while less attention has been paid to students’ thermal comfort in classrooms with particular learning activities, such as architecture design studios, where students spend a long time and perform learning activities with high metabolic rates. For this purpose, we compared the thermal comfort and perceived learning performance of students majoring in architecture (n = 173) between two types of university halls, namely, design studios and typical lecture rooms (N = 15). We applied the classroom–comfort–data method, which included collecting physical, physiological, and psychological data from students and classrooms. Data were collected during the heating season (November 2021–January 2022) in a university building in Jordan. We conducted continuous monitoring combined with periodic measures for indoor temperature, relative humidity, mean radiant temperature, and air speed. Questionnaires, focus groups, and observations were also used to collect subjective data from students. The results showed statistically significant differences (Δμ = 3.1 °C, p < 0.01, d = 0.61) in indoor temperature between design studios and lecture rooms. Only 58% of students’ votes were within the ASHRAE 55-2107 recommended comfort zone. In design studios, 53% of students felt warm compared to 58.8% of students who had a cold sensation in lecture rooms. Students perceived themselves as more productive when they felt cooler. Our research’s significance lies in its injunction that there must be a special thermal comfort guide for educational buildings that are adapted to the local environment and functions of the spaces, cooperatively.

Este trabalho objetiva analisar as características das publicações sobre conforto térmico em salas de aula nas bases de dados Scopus e Web of Science (WOS), identificando as principais fontes, os principais autores e algumas particularidades sobre a produção científica deste tema. O estudo compreende uma revisão bibliográfica que foi realizada a partir de uma pesquisa bibliométrica, na qual por meio de uma análise estatística foi possível mapear e gerar alguns indicadores para o tratamento da informação, constituindo assim, uma abordagem quantitativa e qualitativa. Na base Scopus, foram encontradas 231 publicações relacionadas e na WOS, 135 publicações. Os resultados comparativos mostraram que o número de trabalhos relacionados ao conforto térmico em salas de aula aumentou consideravelmente na última década. Verificou-se que a China é o país com o maior número de publicações. O Brasil surge na 12ª posição na base Scopus e na 10ª posição na base WOS. Também verificou-se a importância do periódico Building and Environment para o tema e que para as salas de aula e ambientes de estudo, há uma estreita relação entre os tópicos conforto térmico, ventilação e qualidade do ar interno, uma vez que estes podem interferir consideravelmente no rendimento e na saúde dos alunos.

The present study was aimed to assess the seasonal variation in glutathione peroxidase (GPx) in seminal plasma of Karan Fries (Tharparkar x Holstein Friesian) bulls. Weekly ejaculates were collected by artificial vagina (42–45°C) during winter (December to mid February), spring (mid February-April), hot dry (May-June) and hot humid (July-August) seasons. Higher concentration of GPx was observed during hot humid season (65.74+0.93 pg mL1) than in winter (59.30+ 0.60 pg mL1), spring (60.67+0.76 pg mL1) and hot dry (62.14+0.90 pg mL1) seasons. The percentage of live spermatozoa decreased during hot humid season as compared to other seasons. The acrosomal integrity also decreased during hot dry (78.7+0.6%) and hot humid (74.2 +0.6%) seasons as compared to winter (83.1+0.6%) and spring (83.4+0.5%) seasons. The supplementation of antioxidant appears essential to Karan Fries bulls during summer season under tropical climatic conditions.

Field study of mixed-mode office buildings in Southern Brazil using an adaptive thermal comfort framework

Thermophysiological responses and thermal comfort of occupants in indoor spaces under different speaking and non-speaking conditions

Positive thermal perception can affect users' climate-controlling behavior, indirectly reducing a building's operational carbon emissions. Studies show that some visual elements, such as window sizes and light colors, can influence thermal perception. However, until recently there has been little interest in the interaction of thermal perception and outdoor visual scenarios or natural elements like water or trees, and little quantitative evidence has been found associating visual natural elements and thermal comfort. This experiment explores and quantifies the extent to which visual scenarios outdoors affect thermal perception. The experiment used a double-blind clinical trial. All tests were done in a stable laboratory environment to eliminate temperature changes, and scenarios were shown through a virtual reality (VR) headset. Forty-three participants were divided into three groups randomly, separately watched VR-outdoor scenarios with natural elements, VR-indoor scenarios, and a control scenario of the real laboratory, then finished a subjective questionnaire conducted to evaluate their thermal, environmental, and overall perceptions while their physical data (heart rate, blood pressure, pulse) was real-time recorded. Results show that visual scenarios could significantly influence thermal perception (Cohen's d between groups > 0.8). Significant positive correlations were found between key thermal perception index, thermal comfort, and visual perception indexes including visual comfort, pleasantness, and relaxation (all PCCs ≤ 0.01). Outdoor scenarios, with better visual perception, rank higher average scores (M ± SD = 1.0 ± 0.7) in thermal comfort than indoor groups (average M ± SD = 0.3 ± 1.0) while the physical environment remains unchanged. This connection between thermal and environmental perception can be used in building design. By being visually exposed to pleasing outdoor environments, the positive thermal perception will increase, and thus reduce building energy consumption. Designing positive visual environments with outdoor natural elements is not only a requirement for health but also a feasible path toward a sustainable net-zero future.