Indoor environmental conditions, attributes of indoor air quality, their mutual correlation and SBS effect studied for non-air-conditioned residential areas of composite climate. As in residential areas like other buildings, toilets are most neglected areas as far as light and ventilation is concern. Author focused on this issue to improve IAQ and reduce SBS effect. 100 cases (50 directly ventilated and 50 indirectly ventilated cases) are taken as case studies/ sample studies and qualitative and quantitative data collected through resident’s personal interview and physical survey of residences (information about temperature, humidity, air velocity, Carbon dioxide concentration and areas of toilets and their ventilator/window collected by using mechanical/digital instruments) respectively. For assessing the indoor air quality level CO2 concentration is measured. Although CO2 is not directly responsible for SBS effect or dangerous; but it is considered as a representative of air pollution and very easily measurable too. After detailed analysis, it is concluded that direct ventilation is preferable for maintaining desired level of air change and indoor air quality.
