Global and diffuse illuminances: Estimation of monthly average hourly values

Abstract

In this paper, using data obtained for locations in the United Kingdom, we introduce the rEg = Ehg /EDg versus So plots, and the rEd = Ehd /EDd versus So plots for the hours centred at 0.5 h ..., 1.5 h ..., 2.5 h ... from the solar noon, where Ehg is the monthly average hourly global illuminance, Ehd the monthly average hourly diffuse illuminance, EDg the monthly average daily global illuminance, EDd the monthly average daily diffuse illuminance (all of them on a horizontal surface), and So the monthly average daily number of hours from sunrise to sunset. From the best fits obtained, Ehg can be computed if EDg and So are known, and Ehd if EDd and So are known.