Indoor Environmental Quality in Split Air-Conditioned Classroom: An Experimental Study on Air Quality and Thermal Comfort in a Warm-Humid Climate

Thermal comfort and Indoor Air Quality (IAQ) are essential for maximising learning and productivity in educational spaces. In India, split air-conditioned (SAC) buildings typically operate in a manual changeover mixed-mode system, switching between air conditioning during hot seasons and natural ventilation during cold seasons to maintain comfortable indoor conditions. To examine thermal comfort perceptions and air quality in these spaces, an experimental study was conducted in an Indian university classroom with 18 students during the summer of 2024. Unlike centralised HVAC systems, SAC units lack a fresh air ventilation provision and rely on natural ventilation and air infiltration for fresh air. In high-occupancy settings, this can lead to elevated CO2 levels, which degrade IAQ. Thermal comfort perception was assessed using regression analysis and probit analysis, with results compared to the ASHRAE PMV model. Regression models were developed to relate the Mean Thermal Sensation Vote (MTSV) to operative temperature and Predicted Mean Vote (PMV). The analysis revealed a neutral and preferred temperature of approximately 28°C, which is notably higher than the temperature specified in Indian standards for air-conditioned buildings. Furthermore, findings suggest that ceiling fans significantly improve comfort, whereas fluctuations of humidity levels were found to be minimal, likely due to the split AC's dehumidifying properties. IAQ parameters, such as PM2.5 and CO2 levels, were monitored throughout the experiment period. CO2 levels peaked at around 2400 ppm, with an average of approximately 1000 ppm, indicating an inadequate supply of fresh air in the studied classroom. PM2.5 levels were often above 50 μg/m3, exceeding the safe limits set by international agencies, further highlighting the lack of adequate ventilation and filtration. This study provides valuable insights into acceptable temperature ranges and air quality concerns for university classrooms with SAC systems, offering guidance for future building design and operation strategies to enhance thermal comfort and IAQ in educational settings in India.

• Publication year

  2025

• Venue

  International Conference on Systems for Energy-Efficient Built Environments

• Publication date

  2025-11-11

• Fields of study

  Computer Science, Environmental Science

• Identifiers
  DOI 10.1145/3736425.3772378
• External record

  Open on Semantic Scholar

• Source metadata

  Semantic Scholar

• No claims are published for this paper.

• No concepts are published for this paper.

• Efficacy of a Demand-Controlled Ventilation System to Enhance Indoor Air Quality and Thermal Comfort in a Split Air-Conditioned Educational Environment

  2025cited by this paper
• Understanding the synergy between heat waves and the built environment: a three-decade systematic review informing policies for mitigating urban heat island in cities

  2024cited by this paper
• Explainable Occupancy Prediction Using QLattice

  2023cited by this paper
• A review of strategies and their effectiveness in reducing indoor airborne transmission and improving indoor air quality

  2022cited by this paper
• A Systematic Review on Indoor Environmental Quality in Naturally Ventilated School Classrooms: A Way Forward

  2021cited by this paper
• Analysis of Air Pollution Data in India between 2015 and 2019

  2021cited by this paper
• Parameters and indicators used in Indoor Environmental Quality (IEQ) studies: a review

  2021cited by this paper
• On the development of a simplified model for thermal comfort control of split systems

  2020cited by this paper
• Evaluation of thermal comfort in two neighboring climatic zones in Eastern India—an adaptive approach

  2020cited by this paper
• pythermalcomfort: A Python package for thermal comfort research

  2020influential reference
• Impact of Outdoor Air Pollution on Indoor Air Quality in Low-Income Homes during Wildfire Seasons

  2019cited by this paper
• Investigation of Indoor Environment Quality in Classroom - Case Study

  2017cited by this paper
• Heating and cooling energy trends and drivers in buildings

  2015cited by this paper
• A thermal comfort field study of naturally ventilated classrooms in Kharagpur, India

  2015cited by this paper
• Association between substandard classroom ventilation rates and students' academic achievement.

  2011cited by this paper
• Developing an adaptive model of thermal comfort and preference

  1998cited by this paper
• Developing an adaptive model of thermal comfort and preference

  1998cited by this paper
• Thermal Environmental Conditions for Human Occupancy

  1992cited by this paper

• No citing papers are available for this paper.