The aim of this research work is to establish a standard sky model for designing excellent daylighting schemes that covers all sky conditions from clear sky to overcast sky.In Part 1, the ldquo;normalized global illuminancerdquo; was defined as a function of the measured global illuminance and solar altitude for estimating the sky luminance distribution.In this paper (Part 2), the ldquo;Relative All Sky Modelrdquo; is introduced. It is the formulae to show the relative sky luminance distribution as a function of the normalized global illuminance. The equation of the zenith luminance concerning the Relative All Sky Model is also a function of the normalized global illuminance.It is called the ldquo;All Sky Zenith Luminancerdquo;.An absolute standard sky luminance distribution model called the ldquo;All Sky Modelrdquo; is introduced that is the multiplication of the Relative All Sky Model and the All Sky Zenith Luminance. The All Sky Model can be calculated from the normalized global illuminance, i. e., from the measured global illuminance and the solar altitude or from the measured global illuminance, the horizontal diffuse illuminance, and the solar altitude. The global illuminance and horizontal diffuse illuminance are easily obtained from even the simplest daylight measurements.The All Sky Model can produce an excellent standard sky for the daylighting design for any place an advanced daylight environment is needed.
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