Identifying The Design Skies for Indian Tropical Climatic Conditions

The current Indian design sky model is inadequate for daylighting design and calculation of annual daylight energy savings in buildings due to which designers are compelled to resort to other sky luminance prediction models like Perez and International Commission on Illumination (CIE) sky models. Perez and CIE sky models are derived from the sky scan data of mostly sub-tropical and temperate regions where the climatic conditions are different from the tropical climatic conditions. The present study attempts to check and compare the adequacy of Perez and CIE sky models for prediction of sky luminance in Indian tropical climatic conditions by comparing model-predicted values with the measured values from the past studies. Further, a framework has been proposed for the identification of CIE design skies for passive window design in the locations where measured sky luminance data is not available. CIE design skies have been recommended for the major climatic zones of the tropical climate of India using the proposed framework.