Development and validation of a framework for indoor thermal comfort in naturally ventilated university classrooms

Purpose This study sought to develop and validate a framework to ensure that indoor thermal comfort in naturally ventilated university classrooms is achieved at the design stage. Design/methodology/approach Measured data were collected using Testo data loggers. The classrooms were modelled and simulated using Autodesk Revit and Autodesk Ecotect. Findings The study found the carbon dioxide (CO2) concentration (540.60 ppm, highest for the dry season and 460.30 ppm, highest for the wet season) to be below the baseline set by regulation as a result of adequate natural ventilation to the indoor space, and the classroom was not overclouded. The study found that the indoor air temperature was 27.60 and 30.85°C for simulated and measured (Predicted Percentage Dissatisfied – PPD; 80.17–43.66%, Predicted Mean Vote – PMV; 2.00 to 0.44 warm to neutral) during the dry season. For the wet season, the measured and simulated values of 26.83 and 25.90 (PPD; 29.31–24.89%, 0.32 to −0.17 neutral to slightly cool). The R-Square (R2) value was 0.7358, and the Root-Mean-Square Deviation (RMSE) of indoor air temperature was 0.8830 after applying the developed framework to alter the building model for the final simulation. Practical implications In university classrooms with natural ventilation, a thorough framework for assessing and improving indoor thermal comfort was effectively created. Adaptive comfort models designed for tropical and subtropical climates, occupant feedback and environmental characteristics (temperature, humidity and air velocity) are all included in the framework. The higher the air velocity, the lower the CO2 concentration within the studied indoor space. This further explains that ventilation has an influence on CO2 concentration in a naturally ventilated classroom. Social implications Another significant contribution of this research to the body of knowledge is the provision of sufficient evidence to confirm the procedure for determining the comfort zone in warm, humid climates where air velocity, CO2 concentration, relative humidity and air temperatures are recorded. Originality/value In retrofit analysis, validated simulation models improve a building’s thermal performance. Thus, the development of validated simulation models for thermal comfort assessment in Ghanaian University classrooms with natural ventilation represents another noteworthy contribution of this study. This serves as a benchmark for the next verified simulation research in Ghana. The study developed and validated a thermal comfort framework for designing a university classroom with natural ventilation, the first in the Ghanaian context.