Search Results (78)

Indoor environmental quality is essential for pupils‘ health, comfort, and academic performance. However, recent studies indicate that indoor air quality (IAQ) in classrooms is often inadequate. This observational study examines the impact of three ventilation concepts on IAQ and thermal comfort under real-life school conditions: manual window airing combined with CO₂ traffic lights, decentralized mechanical ventilation, and centralized mechanical ventilation. Eight classrooms in three elementary schools were monitored from October 2023 to April 2024. Continuous long-term measurements covered CO₂, PM_2.5, VOCs, indoor air temperature, relative humidity and window opening states in the classrooms, and ambient data including PM_2.5 at each school. Significant differences were found in all five indoor parameters across the three ventilation concepts. The decentralized ventilation group achieved the lowest CO₂ concentrations (18–22% lower), while the window airing group showed the highest PM_2.5 levels (mean of 6 µg/m³) and the lowest temperatures (21% of the time below 20 °C). Relative humidity tended to be too low for all concepts, particularly with mechanical ventilation (medians below 40%). Windows in the window airing group were opened approximately twice as long. The findings highlight the benefits of well-operated mechanical ventilation systems and underscore the importance of user awareness and system management. Full article

This study investigates the impact of teacher decisions and other contextual factors on indoor air quality (IAQ) in mechanically ventilated elementary school classrooms using low-cost air quality sensors. Four classrooms at a K–8 school in San Jose, California, were monitored for airborne particulate matter (PM), carbon dioxide (CO₂), temperature, and humidity over seven weeks. Each classroom was equipped with an HVAC system and a portable air cleaner (PAC), with teachers having full autonomy over PAC usage and ventilation practices. Results revealed that teacher behaviors, such as the frequency of door/window opening and PAC operation, significantly influenced both PM and CO₂ levels. Classrooms with more active ventilation had lower CO₂ but occasionally higher PM_2.5 due to outdoor air exchange, while classrooms with minimal ventilation showed the opposite pattern. An analysis of PAC filter material and PM morphology indicated distinct differences between indoor and outdoor particle sources, with indoor air showing higher fiber content from clothing and carpets. This study highlights the critical role of teacher behavior in shaping IAQ, even in mechanically ventilated environments, and underscores the potential of low-cost sensors to support informed decision-making for healthier classroom environments. Full article

Evaluating ventilation behavior inside classrooms in hot climates is fundamental to ensure good indoor air quality and proper thermal comfort, thus guaranteeing a healthy environment for the users. This study analyzes the impact of mixed ventilation strategies, which combine mechanical extractors and organic air cleaners (OACs), on CO₂ concentration and temperature distribution in an air-conditioned classroom with closed doors and windows. We used computational fluid dynamics simulations to analyze the effect of different extractor and OACs configurations on airflow distribution and average temperature, as well as the temporal evolution of average CO₂ concentrations inside the classroom. The configuration with one extractor and two OACs reduces CO₂ concentrations to 613 ppm, representing an effective solution with lower energy consumption. These findings demonstrate that hybrid ventilation systems can significantly improve IAQ and maintain thermal comfort, offering viable and energy-efficient alternatives for enclosed classrooms in hot climate regions. Full article

Indoor environmental quality profoundly impacts student learning outcomes and teacher effectiveness, particularly in primary education, where children spend most of their developmental years. The study compares the New Zealand Ministry of Education’s Designing Quality Learning Spaces (DQLS) version 2.0 for primary school classrooms with international standards set by OECD countries to develop IAQ and thermal comfort best practices in New Zealand across six climate zones. The research evaluates indoor air quality (IAQ) and thermal comfort factors affecting students’ and teachers’ health and performance. Using Ladybug and Honeybee plugin tools in Grasshopper with Energy Plus, integrated into Rhino 7 software, the study employed advanced building optimisation methods, using multi-criteria optimisation and parametric modelling. This approach enabled a comprehensive analysis of building envelope parameters for historical classroom designs, the Avalon block (constructed between 1955 and 2000). Optimise window-to-wall ratios, ceiling heights, window placement, insulation values (R-values), clothing insulation (Clo), and window opening schedules. Our findings demonstrate that strategic modifications to the building envelope can significantly improve occupant comfort and energy performance. Specifically, increasing ceiling height by 0.8 m, raising windows by 0.3 m vertically, and reducing the window-to-wall ratio to 25% created optimal conditions across multiple performance criteria. These targeted adjustments improved adaptive thermal comfort, ventilation, carbon dioxide, and energy efficiency while maintaining local and international standards. The implications of the findings extend beyond the studied classrooms, offering evidence-based strategies for overall design and building performance guidelines in educational facilities. This research demonstrates the efficacy of applying computational design optimisation during early design phases, providing policymakers and architects with practical solutions that could inform future revisions of New Zealand’s school design standards and align them more closely with international best practices for educational environments. Full article

Schools are vital infrastructures where students acquire essential skills and foster social values. Indoor air quality (IAQ) is of paramount importance in schools, given that students spend a considerable amount of time indoors. This study examines the influence of a natural green structure (NGS) on IAQ in an Eco-Campus classroom. The IAQ of a classroom with an NGS was compared to that of an adjacent classroom without an NGS. The thermal conditions were monitored, including air temperature (T) and relative humidity (RH), as well as indoor pollutants, including carbon dioxide (CO₂), volatile organic compounds (VOCs), and particulate matter (PM_2.5 and PM₁₀). The findings indicated a substantial improvement in indoor air quality in the classroom where the green structure was installed. This study lends support to the incorporation of biophilic solutions as sustainable approaches to fostering healthier learning environments, which in turn can lead to improvements in student performance and well-being. Full article

To address the limitations of conventional split air conditioners (SACs) that lack proper ventilation, resulting in indoor pollutant buildup and health risks, this study develops and evaluates the performance of a sustainable hybrid air conditioning system that integrates Indirect Evaporative Cooling (IEC) with SAC to enhance indoor air quality (IAQ), thermal comfort, and energy efficiency in tropical climates, compared with a standalone SAC system. The hybrid SAC + IEC system is designed to meet stringent comfort criteria while reducing indoor formaldehyde and carbon dioxide concentrations. Experiments were conducted in a controlled classroom environment using a cross-flow tubular heat exchanger with optimized nozzle configurations. Temperature, humidity, and pollutant levels were continuously monitored under varying tropical conditions. The IEC achieved an average cooling capacity of 1430 W, substantially exceeding the target of 566 W, and reduced the fresh air dry-bulb temperature by up to 8.79 °C, maintaining primary air near 25.2 °C, with energy efficiency ratios varying between 30% and 100%. The hybrid SAC + IEC system outperforms the standalone SAC system in maintaining acceptable formaldehyde and CO₂ levels while delivering comfortable thermal conditions within the indoor standards. These results demonstrate that the Hybrid SAC + IEC system optimizes energy efficiency and improves cooling performance and indoor air quality (IAQ) for tropical environments. Full article

Indoor air quality (IAQ) in schools significantly affects health and academic performance; however, effective interventions for poor air quality remain limited, particularly in settings with restricted natural ventilation. This study evaluated the effectiveness of ventilation-type air purifiers in improving classroom IAQ in a South Korean elementary school. PM₁₀, PM_2.5, and CO₂ concentrations were monitored over 18 days (14–31 May 2021) in two classrooms—one equipped with a ventilation-type air purifier and the other serving as a control. In the classroom with the air purifier, daily average concentrations of PM₁₀, PM_2.5, and CO₂ decreased by 23.7%, 22.8%, and 21.1%, respectively, from baseline levels. The air purifier effectively reduced pollutant infiltration during periods of severe outdoor air pollution and stabilized pollutant levels during active class hours. Its efficacy was particularly prominent under conditions of restricted natural ventilation, high indoor activity, and fluctuating outdoor pollution levels. IAQ varied significantly between weekdays and weekends; pollutant levels were higher on weekdays due to occupancy and classroom activities, whereas weekends exhibited reduced concentrations. These findings suggest that ventilation-type air purifiers provide a viable strategy for improving IAQ in schools with limited ventilation. Future research should examine their long-term performance across different seasons and architectural settings. Full article

The quality of indoor environments within educational settings significantly impacts the health, safety, and comfort of occupants. In this manuscript, a simplified Classroom Indoor Air Quality (CIAQ) Risk Index, aimed at assessing the potential ability of classrooms to maintain CO₂ levels within acceptable limits, is introduced. Comprising three primary components—the likelihood of surpassing predefined CO₂ thresholds, the potential number of individuals exposed, and the classroom’s capacity to withstand or mitigate threats—this index serves as a valuable compliance tool during both the design phase and operational management of educational spaces. Additionally, apart from presenting the index framework, a sensitivity case study analysis is carried out to verify the suitability of the proposed method and the sensitivity of the factors involved. Through this analysis, the robustness of the CIAQ Risk Index in various scenarios is demonstrated. By quantifying and evaluating potential risks associated with indoor air quality, the CIAQ Risk Index contributes to ongoing efforts to create healthier indoor environments. Furthermore, it facilitates the identification of budgetary mitigation strategies that should positively affect the air quality; among those, an intervention, retrofitting, and ventilation improvements can be listed. Through proactive risk identification and appropriate actions, including regulation adjustments and ventilation strategies, the reduction in health problems, the enhancement of well-being, and the improvement of overall performance and quality of life for educational communities can be achieved. Full article

This paper comprehensively investigates the performance of various strategies for predicting CO₂ levels in school classrooms over different time horizons by using data collected through IoT devices. We gathered Indoor Air Quality (IAQ) data from fifteen schools in Navarra, Spain between 10 January and 3 April 2022, with measurements taken at 10-min intervals. Three prediction strategies divided into seven models were trained on the data and compared using statistical tests. The study confirms that simple methodologies are effective for short-term predictions, while Machine Learning (ML)-based models perform better over longer prediction horizons. Furthermore, this study demonstrates the feasibility of using low-cost devices combined with ML models for forecasting, which can help to improve IAQ in sensitive environments such as schools. Full article

This study investigates indoor air quality (IAQ) and thermal comfort in Italian university classrooms, considering seasonal variations. Poor IAQ can impair students’ cognitive performance and well-being, making ventilation strategies crucial. The aim is to assess CO₂ levels, temperature, and humidity, analyzing their interactions across seasons. A monitoring protocol was applied in three classrooms using NDIR sensors and a microclimate assessment system. Sensors were placed strategically to capture representative data in 20 days in spring and autumn. Results indicate that CO₂ levels peaked at 2324.2 ppm in autumn, significantly exceeding the 1000 ppm threshold, whereas spring levels remained below 953.4 ppm. Relative humidity ranged from 32.7% to 55.6%, with higher values in autumn. Temperatures varied from 19.1 °C to 27.5 °C, with warmer conditions in spring. Strong positive correlations (always greater than 0.70) between CO₂ and humidity suggest inadequate air exchange reduces IAQ, potentially affecting cognitive performance. This research provides valuable insights for improving student well-being through better air quality management. This research provides valuable insights for optimizing classroom environments, supporting cognitive performance, and improving student well-being through better air quality management. Full article

Indoor air quality (IAQ) plays a vital role in supporting both the physical and mental well-being of individuals in enclosed spaces, and the role of mechanical ventilation systems has gained increasing attention due to building design’s focus on energy efficiency and thus airtight constructions. This study investigated the pre–post effects of installing a heat recovery mechanical ventilation system (MVHR) on indoor air quality in a high school classroom in Ferrara, Italy. The analysis focused on experimental measurements of temperature (T), relative humidity (RH), and carbon dioxide (CO₂) both inside and outside the same classroom, which had constant occupancy (17 students) for an entire school year, allowing a comparison between natural and mechanical ventilation. With a comprehensive approach, particulate matter (PM_2.5), volatile organic compounds (VOCs), and radon levels (Rn) were monitored as well, after the installation of the MVHR. By comparing natural and mechanical ventilation, the study highlights the strengths and limitations of the ventilation system implemented, together with an evaluation of the system’s energy consumption, including a 2 kW post-heating battery. In terms of results, the MVHR demonstrated clear benefits in managing CO₂ levels and improving sensory, olfactory, and psychophysical well-being, as well as the attention levels of students. In detail, under natural ventilation, peak concentrations exceeded 4500 ppm, while mechanical ventilation kept them below 1500 ppm. The average CO₂ concentration during occupancy dropped from 2500 ppm to around 1000 ppm, achieving a 62% reduction. However, beneficial effects were not observed for other parameters, such as PM_2.5, VOCs, or radon. The latter displayed annual average values around 21 Bq/m³ and peaks reaching 56 Bq/m³. Full article

This study assesses indoor air quality (IAQ) in two schools in the Democratic Republic of Congo (DRC), contributing scientific data for a developing tropic such as the DRC marked by the absence of sufficient study on the indoor environmental quality (IEQ) in school buildings. Over ten weeks, we monitored IEQ parameters in two schools, considering their unique geographical and environmental settings. Using a calibrated IEQ multiprobe and particle counters, we measured the CO₂ levels, temperature, relative humidity, and particulate matter (PM). Our data analysis, which included ANOVA and correlation assessments, revealed a concerning trend. We found that the CO₂ and PM concentrations in the classroom were significantly high, often exceeding recommended safety thresholds. The current natural ventilation systems were found to be inadequate, particularly in managing CO₂ concentrations and PM levels influenced by proximity to industrial activities. Our study recommends that schools in similar settings adopt mechanical ventilation systems with high-efficiency particulate air (HEPA) filters to improve IAQ. We also recommend regular monitoring and dynamic air quality adjustment based on real-time data to ensure the effectiveness of implemented interventions. Furthermore, we propose that future studies focus on a broader range of environmental conditions and include many schools and educational buildings to enhance the generalisability of the findings. Long-term health outcomes and the cost-effectiveness of different ventilation strategies should also be explored to develop adapted, sustainable interventions for improving student well-being and performance in schools globally. Full article

Climatic changes lead to many extreme weather events throughout the globe. These extreme weather events influence our behavior, exposing us to different environmental conditions, such as poor indoor quality. Poor indoor air quality (IAQ) poses a significant concern in the modern era, as people spend up to 90% of their time indoors. Ventilation influences key IAQ elements such as temperature, relative humidity, and particulate matter (PM). Children, considered a vulnerable group, spend approximately 30% of their time in educational settings, often housed in old structures with poorly maintained ventilation systems. Extreme weather events lead young students to stay indoors, usually behind closed doors and windows, which may lead to exposure to elevated levels of air pollutants. In our research, we aim to demonstrate how real-time monitoring of air pollutants and other environmental parameters under extreme weather is important for regulating the indoor environment. A study was conducted in a school building with limited ventilation located in an arid region near the Red Sea, which frequently suffers from high PM concentrations. In this study, we tracked the indoor environmental conditions and air quality during the entire month of May 2022, including an extreme outdoor weather event of sandstorms. During this month, we continuously monitored four classrooms in an elementary school built in 1967 in Eilat. Our findings indicate that PM2.5 was higher indoors (statistically significant) by more than 16% during the extreme event. Temperature was also elevated indoors (statistically significant) by more than 5%. The parameters’ deviation highlights the need for better indoor weather control and ventilation systems, as well as ongoing monitoring in schools to maintain healthy indoor air quality. This also warrants us as we are approaching an era of climatic instability, including higher occurrence of similar extreme events, which urge us to develop real-time responses in urban areas. Full article

Indoor air quality (IAQ) in schools significantly impacts occupant health and academic performance, especially in naturally ventilated (NV) classrooms, where CO₂ levels are often elevated. This systematic review synthesises findings from 125 studies, examining CO₂ as an indicator of ventilation rates (VRs) and its impact on IAQ, health, and academic performance in NV primary school classrooms. This analysis highlights seasonal and temporal variations in CO₂ concentrations, revealing a median CO₂ concentration of 1487 ppm across 2444 classrooms, with 81% exceeding the recommended 1000 ppm threshold. Influencing factors include VR, occupant density, generation rates, and occupant behaviours. Increased VRs consistently lowered CO₂ levels and enhanced IAQ. CO₂ concentrations correlated with particulate matter, volatile organic compounds, bioeffluents, microbial concentrations, and bacteria and fungi levels, but not with traffic-related pollutants like NO₂, which is associated with asthma prevalence. Elevated CO₂ levels consistently correlated with fatigue, headaches, respiratory symptoms, reduced academic performance and absenteeism, suggesting potential socio-economic benefits of increased VRs. However, effective IAQ management requires balancing ventilation with considerations of thermal comfort, noise, and outdoor pollutants. The findings highlight the need for standardised IAQ indices and CO₂ monitoring protocols, offering insights for future research, intervention design, and investment aimed at enhancing classroom environments. Full article

This study intended to understand whether teachers’ perceptions of indoor air quality (IAQ) during classes aligned with the real levels of air pollutants and comfort parameters. For this purpose, an IAQ monitoring survey based on low-cost sensors using a multi-parameter approach was carried out in nine classrooms (a total of 171 monitored classes) in a Portuguese school. In each monitored class, the perception of IAQ reported by the teacher was assessed using a scale from 1 (very bad IAQ) to 10 (very good IAQ). Several exceedances regarding national legislation were found, with temperature being the parameter with a higher percentage of exceedance in all the studied classrooms (46%), followed by PM₁₀ (32%), and then CO₂ (27%). Temperature was found to be the only environmental parameter that was significantly associated with lower IAQ perception reported by the teachers, highlighting that typical pollutants such as CO₂ (which can be identified as stuffy air) did not contribute to the teachers’ perceptions. Full article