Determination of time and sun position system

Abstract Accurate calculations and recording of time either in local clock time or true solar time in regular daytime measurements of sun and sky radiation and light, in computer programs evaluating solar irradiance or sunlight and skylight illuminance currently apply differently defined solar hour angles as well as angularly determined solar altitude and azimuth coordinates. The historical basis of solar geometry used to construct sundials for the measurements of true solar time were gradually replaced during Middle Ages by spherical trigonometry relations of solar altitude and azimuth angles including solar declination, local geographical latitude and time changes in better precision. However, in different scientific and practical applications like in solar energy or daylight calculations are currently used several systems and formulae defining sun position and time which need to be unified and standardised in computer programs or measurement evaluations. Potential confusion and inconsistent results should be avoided, possible mistakes have to be checked and corrected after the valid ISO international standard. This paper discusses various approaches considering time and sun coordinates in different systems.

[1]  S. Darula,et al.  Daylight Science and Daylighting Technology , 2011 .

[2]  C. B. Wilson,et al.  The shading of the ground by buildings , 1976 .

[3]  Lucien Wald,et al.  The SG2 algorithm for a fast and accurate computation of the position of the Sun for multi-decadal time period , 2012 .

[4]  Thomas A. Markus,et al.  Buildings, climate, and energy , 1980 .

[5]  Geoffrey G. Roy,et al.  An Implementation of the Method of Aperture Meridians for the ISO/CIE Standard General Sky , 2007 .

[6]  T. Muneer,et al.  Solar Radiation and Daylight Models: For the Energy Efficient Design of Buildings , 1997 .

[7]  M. Iqbal.  An introduction to solar radiation , 1983 .

[8]  Stanislav Darula,et al.  Applying Solar Geometry to Understand the Foundation Rituals of ‘Old Kingdom’ Egyptian Pyramids , 2008 .

[9]  P. R. Tregenza,et al.  Daylighting: Architecture and Lighting Design , 2011 .

[10]  Vice President,et al.  AMERICAN SOCIETY OF HEATING, REFRIGERATION AND AIR CONDITIONING ENGINEERS INC. , 2007 .

[11]  Základy využívania slnečného žiarenia , 1986 .

[12]  I. Reda,et al.  Solar position algorithm for solar radiation applications , 2004 .

[13]  Richard Kittler,et al.  Analemma, the Ancient Sketch of Fictitious Sunpath Geometry—Sun, Time and History of Mathematics , 2004 .

[14]  Marcus Vitruvius Pollio,et al.  De Architectura, Libri Decem , 2008 .

[15]  D. Yogi Goswami,et al.  Solar Energy Pocket Reference , 2005 .

[16]  Corinna Rossi,et al.  Architecture and mathematics in ancient Egypt , 2004 .