Daylighting is one of the basic components of passive solar building design and its estimation is essential. In India there are a few available data of measured illuminance as in many regions of the world. The Indian climate is generally clear with overcast conditions prevailing through the months of June to September, which provides good potential to daylighting in buildings. Therefore, an analytical model that would encompass the weather conditions of Indore was selected. Hourly exterior horizontal and slope daylight availability has been estimated for Indore using daylight modeling techniques based on solar radiation data. (c) 2006 Elsevier Ltd. All rights reserved.