A thorough analysis of sky distributions can help in the prediction of daylight patterns and thus provides a good understanding of architectural window and building envelope design. This paper introduces three methods of analysis for sky distributions, namely the relative indicatrix and gradation classification, and two other independent methods established by Kittler and Tregenza. All these three methods were verified for their feasibility for analysing the extreme daylight conditions in Singapore, which is located at the equator. The most suitable approach, from Tregenza, was eventually adopted in analysing the measured data from Singapore IDMP station. The prediction of frequent sky patterns in Singapore was based on the CIE Standard General Skies, as well as a complete version considering all 36 theoretical sky types.
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References
1.
Commission Internationale de l'Eclairage. Guide to Recommended Practice of Daylight Measurement. CIE 108, 1994.
2.
Commission Internationale de l'Eclairage. Spatial Distribution of Daylight-CIE Standard General Sky. CIE Draft Standard DS 011.3/E, 2002.
3.
Li DHW, Lau CCS, Lam JC. A study of 15 sky luminance patterns against Hong Kong data. Archit Sci Rev2003; 46: 61–68.
4.
IDMP-CIE. The IDMP Network. CIE. Retrieved 26 August 2005, from http://idmp.entpe.fr/.
5.
ISO. Spatial Distribution of Daylight–CIE General Sky. ISO Standard 15469, 2004.
6.
Kittler R.Luminance distribution characteristics of homogeneous skies: a measurement and prediction strategy. Lighting Res Technol1985; 17: 183–188.
7.
Kittler R, Hayman S, Ruck N, Julian W. Daylight measurement data: methods of evaluation and representation. Lighting Res Technol1992; 24: 173–187.
8.
Kittler R.Relative scattering indicatix: derivation from regular radiance/luminance distribution sky scans. Lighting Res Technol1993; 25: 125–127.
9.
Kittler R.The need for standard skies and models for energy conservation measures. Lighting Res Technol1994; 26: 171–180.
10.
Kittler R.Some qualities of scattering functions defining sky radiance distributions. Solar Energy1994; 53: 511–516.
11.
Kittler R, Darula S. Prevailing sky conditions: identifying simple parameters for definition. Lighting Res Technol1997; 29: 63–68.
12.
Kittler R, Perez R, Darula S. Sky classification respecting energy-efficient lighting, glare and control needs. J Illuminating Eng Soc1997; Winter: 57–68.
13.
Kittler R, Perez R, Darula S. A new generation of sky standards. Lux Europa. Proceedings of the 8th European Lighting Conference, Amsterdam, 1997.
14.
Kittler R, Darula S, Perez R. A set of standard skies. Polygrafia, 1998.
15.
Kittler R, Darula S, Gueymard CH. Reference luminous solar constant and solar luminance for illuminance calculations. Solar Energy2005; 79: 559–565.
16.
Kittler R, Darula S, Wittkopf SK. Outdoor illuminance levels in the tropics and their representation in the Virtual Sky Dome. Archit Sci Rev2006; 49 (in press).
17.
Lam KP. Mapping of the sky luminance distribution and computational prediction of daylighting performance in Singapore. Research report. National University of Singapore, 1997.
18.
Lam KP, Mahdavi A, Ullah MB, Ng E, Pal V. Evaluation of six sky luminance prediction models using measured data from Singapore. Lighting Res Technol1999; 31: 13–17.
19.
NEA. Meteorological services or local weather. Singapore: NEA. Retrieved 24 January 2006, from http://app.nea.gov.sg.
20.
Tregenza PR. Subdivision of the sky hemisphere for luminance measurements. Lighting Res Technol1987; 19: 13–14.
21.
Tregenza PR. Standard skies for maritime climates. Lighting Res Technol1999; 31: 97–106.
22.
Tregenza PR. Analysing sky luminance scans to obtain frequency distributions of CIE Standard General Skies. Lighting Res Technol2004; 36: 271–281.
23.
Ullah MB. International Daylighting Measurement Programme-Singapore Data I: quality of data gathered over a long period. Lighting Res Technol1996; 28: 69–74.
24.
Ullah MB. International Daylighting Measurement Programme-Singapore Data II: luminous efficacy for the tropics. Lighting Res Technol1996; 28: 75–81.
25.
Ullah MB. International Daylighting Measurement Programme-Singapore Data III: building energy savings through daylighting. Lighting Res Technol1996; 28: 83–87.
26.
University of Ljubljana. Sky Scans EKO. University of Ljubljana. Retrieved 13 October 2005, from http://lrf.fe.uni-lj.si/ekoscan/ekolum.htm.
27.
Wittkopf SK. A method to construct Virtual Sky Domes for use in standard CAD-based light simulation software. Archit Sci Rev2004; 47: 275–286.
28.
Wittkopf SK. Evaluation of Virtual Sky Domes for the prediction of daylight performance with radiosity-based light simulation software. Archit Sci Rev2005; 48: 173–177.
29.
Wittkopf SK, Yuniarti E, Soon LK. Prediction of energy savings with anidolic integrated ceiling across different daylight climates. Energy Buildings2006; 38: 1120–1129.
30.
Wittkopf SK. Daylight performance of anidolic integrated systems under different sky conditions. Solar Energy (in press).
31.
Wittkopf SK, Soon LK, Yuniarti E, Grobe L. Virtual Sky Domes–making the CIE/ISO Standard General Sky available for CAD-based light simulation software. eSim2006. Proceedings of the bi-annual conference of IBPSA-Canada, Toronto, 2006.
