The increasing number of churches in Nigeria has led to a growing demand for church auditoria for Christian worship. However, these buildings are often converted without prioritising the comfort and well-being of worshippers. This study focuses on the indoor environmental performance of church buildings in North-East Nigeria to develop new design guidelines for improving the environmental performance of these facilities. Indoor Environmental Quality (IEQ) refers to the interaction of indoor air quality and non-air quality-related aspects that create a comfortable indoor environment and enhance well-being. The study aims to compare the indoor index performances of various churches in North-East Nigeria and compare findings to exposure limits and recommendations established by Indoor Environmental Quality.The research study focuses on the indoor environmental performance of church buildings in North-East Nigeria, with the aim of developing new design guidelines to improve the comfort and well-being of worshippers. It addresses the growing demand for church auditoria in Nigeria and the lack of prioritization for the indoor environment in these buildings.