Assessment of Daylight Intensity as a Function of the Ratio of the Window Area and Total Room Volume for Office Buildings in Jos, Nigeria

Abstract

The subjective data for this study was obtained from questionnaires while the objective data was obtained from measurement instruments. An 80% combined votes of respondents found the level of lighting inadequate. This is in consonance with objective measurements, which show interior light level way below recommended standards for the building under research. This has led to the wasteful use of energy for lighting purposes in the day time. However, day light intensity increases as the day proceeds. Also, a linear relationship between the ratio of Operable Window Area to Total Office Volume and day light intensity was established. The lower the Operable Window Area to total Office Volume Ratio, the lower the day light intensity. Hence, by simple linear regression analysis, it concluded that the ratio of operable window area to total room volume of 0.0273 would be required for an acceptable indoor day light intensity of 400 lux in East-Facing Office Buildings with 5mm clear glass windows in Jos, Nigeria. However, all the offices studied showed an insufficient average ratio of 0.0023.