Offor, J. N. PhD and Chijioke, O. E. PhD

In tropical countries, the effect of climate change and its consequent temperature rise are sources of worry to many environmentalists and concerned citizen worldwide. Building sector consume great quantity of energy which involves burning of fossil fuel that contributes significant amount of greenhouse gas emissions into the atmosphere. Improving proving thermal comfort of occupants in a free-running building and avoiding active and fossil-based systems, is the main challenge in many cities all over the world. This paper therefore focused on the evaluation of the influence of natural ventilation on indoor thermal comfort of occupants of secondary school classroom during the hot season in Enugu Metropolis. Both primary and secondary sources of data were adopted. Data collecting instruments include Digital Anemometer and Thermometers. Results of the descriptive analysis of data collected showed that high indoor temperature range of between 29.8oC and 35.3o C was main the factor that caused indoor discomfort during dry season. There was also low air velocity range of between 0,11m/s and 0.5m/s and the existing Window-to-Wall Ratio (WWR) obtained spans between 13% and 21% for the classrooms examined. From the result of the regression analysis used to evaluate the influence of natural ventilation variables on indoor comfort, the probability values of indoor air temperature, indoor air velocity and indoor relative humidity were (0.0209), (0.0498) and (0.1382). This result implied that, indoor temperature and indoor air velocity had significant influence on the thermal comfort conditions of the classrooms as the probability values were less than significance level of 0.05. Whereas, indoor relative humidity had no significant influence on the thermal comfort condition as the probability value was above significance level of 0.05. The conclusion was that to improve indoor comfort in classrooms, efforts should focus on increasing air flow rate through the classrooms and this would facilitate the reduction of indoor temperature.