Daylight is an invaluable aspect of nature, essential for survival of all living organisms. At many locations of India, daylight illuminance data is not available. In this invention, an attempt has been made to measure and generate the annual data of daylight illuminance levels. This invention discusses the daylight illuminance measurement and its assessment for moderate climate zone of India. The work also investigates the correlations between daylight illuminance and weather parameters, discusses the development of multivariable regression equations to estimate daylight illuminance intensities. These equations are based on the actual observed daylight illuminance intensities measured at specific time intervals during February 2015 to January 2016. The analysis finds a better association (0.769, 0.862 and 0.747) between daylight illuminance and specific climate variables during cloudy days (July) as compared to other climatic seasons. The average percentage errors of the regression equations vary from 3.65% to 11.94 %, indicating better level of accuracy.