Evaluating Adaptive Thermal Comfort Model For Naturally Ventilated Classrooms In Adama City, Ethiopia

Abstract

In educational institutions, a conducive and comfortable atmosphere is crucial to create effective leaning environment for students. Naturally ventilated and thermally comfortable school buildings improve students’ health, wellbeing and their educational performance since they spend considerable amount of their time inside classrooms. This study is confined with in Adama city, Ethiopia; only on 4 purposively selected school buildings which aimed to evaluate the orientation based adaptive model of naturally ventilated classrooms to enhance thermal comfort. The study uses both qualitative and quantitative data gathering approaches and implemented by using primary and secondary data sources. 355 respondents were selected using proportionate stratified sampling technique with 12 classroom building blocks (3-blocks per school). Required data were collected for 3 weeks on the months of March and April. Based on the data from the building occupants, objective measurements and software simulation result, classroom building oriented towards the south, southeast and southwest axis are uncomfortable for their users and highly susceptible for the harsh sun penetrating into the classroom. To regulate the indoor air temperature and maximize the natural ventilation for south oriented building with VSA of 60° and HSA of 50° result a wingwall with a depth of 1m and roof eave overhang having a depth of 1.1m will effectively minimize the direct solar gain and increase the natural ventilation by allowing more fresh air inlet from southwest direction at an angle of 45°. For buildings oriented towards the southwest direction, a VSA of 50° and HSA of 48° results a wingwall having a depth of 1.08m and roof eave overhang with 1.6m depth effectively blocks the harsh sun entering the room and increases the amount of fresh air inlet the room. For buildings oriented towards the east and southeast axis, a wingwall having a depth of 1m and a roof eave overhang of a minimum of 0.4m will allow fresh air to enter the room and minimize the direct solar heat penetration into the room. By applying this passive design strategy, the temperature of the classroom during the peak hottest day results a reduction in indoor temperature from 33.3 ℃ and 20℃ for maximum and minimum indoor temperature respectively to 27.5℃ and 18℃. This shows, the recommended design strategy creates a significant change in creating a thermally comfortable and naturally ventilated classrooms.