ASSESSMENT OF INDOOR AIR QUALITY, THERMAL COMFORT AND VENTILATION PERFORMANCE FOR HEALTHY LEARNING ENVIRONMENTS IN POLYTECHNICS IN SOUTH-WEST NIGERIA

Abstract

The indoor environment in which students learn affects their health,
comfort, attendance and performance. This study assessed indoor air
quality, thermal comfort and ventilation performance in learning spaces
of polytechnics in South-West Nigeria and related them to occupant
perception. A field-measurement and survey design combined physical
monitoring in 18 classrooms, lecture halls and studios with a validated
survey of 480 occupants. Mean carbon dioxide concentration was 1,486
ppm, exceeding the 1,000 ppm threshold in 68.4% of measurements.
Mean PM2.5 was 42.6 µg/m³, exceeding the WHO guideline of 15
µg/m³ in 72.8% of measurements. Thermal discomfort was reported by
62.4% of occupants, with a mean predicted mean vote (PMV) of +1.24
and predicted percentage dissatisfied (PPD) of 38.6%. The mean air
exchange rate was 2.4 ACH against a recommended 4 to 6 ACH, and
only 27.8% of spaces met the recommendation. Occupant perception
correlated significantly with measured conditions, and occupancy
density, ventilation rate and building age explained 58% of the variance
in carbon dioxide concentration. The study provides an empirical
baseline and evidence-based recommendations for improving
ventilation, reducing occupancy density and enhancing thermal comfort
in Nigerian polytechnic learning environments.