Assessing Thermal Performance In Two Classroom Building Types In Warm Humid Climate Imo State, Nigeria

Abstract

Achieving energy efficiency in educational buildings in countries located in the tropical regions is a big challenge because of very high temperatures and humidity. The problem is further complicated by designs that encourage the use of mechanical ventilating systems to provide thermal comfort. This paper presents the report of fieldwork carried out in primary schools in Imo State, Nigeria. It involved two naturally ventilated classroom building types categorized as short wall and enclosed wall classrooms. The aim was to determine and compare their thermal performance so as to provide information for use in design of sustainable school buildings in warm and humid environments like Nigeria. The data (environmental parameters and physical measurements) of these classrooms were collected during the rainy season and dry season. Results of the correlation analysis of the retrieved data showed that the two classroom types were in thermal compliance with the requirements of ASHRAE Standard 55. However, the relationship between the outdoor temperature and the indoor temperature in the short wall classroom-type was stronger (r²= .856), than the relationship found in the enclosed wall classroom-type (r²= .722). Furthermore, the prevailing daily mean indoor temperatures were higher in the enclosed wall classroom type. The difference in thermal performance in these two building-types is likely as a result of the difference in their building envelopes. It was concluded that the short wall classroom-type has a greater potential to contribute to reduced energy use in buildings. It was recommended that the short wall concept in the design of classroom blocks be adopted in the warm and humid climate, in Nigeria.