The method of aperture meridians: a simple calculation tool for applying the ISO/CIE Standard General Sky

Abstract

Following the recent publication of the CIE Standard General Sky,¹ adopted as an ISO Standard,² an Application Guide is expected to be prepared by CIE Technical Committee 3-37 with the aim of explaining and simplifying its practical use. The advantage of the 15 Standard Sky Luminance Distributions (SSLD) adopted by CIE and ISO in relative terms normalized to zenith luminance is not only in the more versatile definition of skylight in various locales and daylight climate regions, but also in the possibility of simulating annual daylight profiles in absolute units based on typical luminance sky patterns. As well as complex computer programs for producing isoluminance contours in plan projections of the sky vault, a simpler tool is needed to calculate absolute sky luminance within the solid angle of arbitrarily dimensioned apertures, especially vertical windows. With this objective in mind, the Method of Aperture Meridians or MAM for any SSLD is introduced in this paper.

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References

CIE—Commission Internationale de l’Éclairage . Spatial distribution of daylight—CIE Standard General Sky. CIE Standard S 011/E:2003. Vienna: CIE Central Bureau, 2003.

ISO—International Standardisation Organisation . Spatial distribution of daylight—CIE Standard General Sky. ISO Standard 15469:2004. Geneva: ISO, 2004.

Kittler R. Luminance distribution characteristics of homogeneous skies: a measurement and prediction strategy. Light. Res. Technol. 1985; 17: 183-188.

Kittler R , Darula S. Scattering indicatrix: a primary characteristic of light diffusion for sky patterns. Build. Res. J. 2001; 49: 273-285.

Kittler R , Darula S , Perez R. A set of standard skies. Bratislava: Polygrafia, 1998.

Kittler R , Darula S , Perez R. Advantages of new sky standards: more realistic modelling of daylight conditions in energy and environmental studies. Int. J. of Energy, Envir. Econ. 1999; 8: 65-72.

Darula S , Kittler R. Research of daylight conditions in Slovakia for the effective building design based on the CIE standards and measurements at Bratislava. Final Report VEGA 2/2067/24. Bratislava: ICA SAS, 2004.

Darula S , Kittler R , Gueymard ChA . Reference luminous solar constant and solar luminance for illuminance calculations. Solar Energy, 2005; 79: 559-565.