1、CIE 110 94 E 9006345 0005048 225 ISBN 3 900 734 52 6 COMMISSION INTERNATIONALE DE LCLAIRAGE I NTERNATIONAL COM M ISSION ON I LLU M I NATION INTERNATIONALE BELEUCHTUNGSKOMM ISSION Spatial Distribution of Daylight - Luminance Distributions of Various Reference Skies CIE 110-1 994 CIE 1 10.1-1 995 Revi
2、sion 1 UDC: 551.521. i Descriptor: Solar radiation 628.9.02 1 Sunlight 681.782.43 Photometers for global radiation measurement COPYRIGHT International Commission on IlluminationLicensed by Information Handling ServicesCIE 110 94 P 9006145 0005049 1b1 f )a ISBN 3 900 734 52 6 COMMISSION INTERNATIONAL
3、E DE LCLAIRAGE INTERNATIONAL COMMISSION ON ILLUMINATION INTERNATIONALE BELEUCHTUNGSKOMM ISSION Spatial Distribution of Daylight - Luminance Distributions of Various Reference Skies CIE 110-1994 UDC: 551.521.1 628.9.02 I 681.782.43 Descriptor: Solar radiation Sunlight Photometers for global radiation
4、 measurement COPYRIGHT International Commission on IlluminationLicensed by Information Handling Services CIE 110 94 I 9006345 0005050 983 CIE 110-1994 1 “The following members of TC 3-09 took part in the preparation of this Technical Report. committee comes under CIE Division 3“. The Chair man: K. M
5、ATSUURA Members: S. AYDINLI P. CHAUVEL R. DOGNIAUX J. D. KENDRICK R. KITTLER P. LITTLEFAIR T. NAGATA H. NAKAMURA E. NEEMAN S. SELKOWITZ Japan Germany France Belgium Australia Slovakia Great Britain Japan Japan Israel USA 111 COPYRIGHT International Commission on IlluminationLicensed by Information H
6、andling ServicesI CIE 110 94 I 9006145 0005051 BLT CIE 110-1994 CONTENTS 1, INTRODUCTION 2. DEFINITIONS OF VARIOUS REFERENCE SKIES 2.1 Reference skies to be defined 2.2 Three basic reference skies 2.3 Reference skies for specified application 3. CLEAR SKY AND OVERCAST SKY AS REFERENCE SKIES 3.1 Clea
7、r sky 3.2 Overcast sky 4. GENERAL SKY INCLUDING INTERMEDIATE SKY 4.1 Studies mainly by experimental method 4.2 Studies mainly by theoretical method 4.3 Averaged intermediate sky luminance 5. AVERAGED SKIES FOR SPECIFIED APPLICATION 5.1 BRE average sky 5.2 Mean sky by Nakamura, Oki et al. 5.3 Composi
8、tion of average sky and mean sky as reference skies 6. APPENDICES AND LIST OF SYMBOLS 6.1 Studies on the various skies 6.2 Method of composing average sky and mean sky 6.3 Illuminances from direct sunlight to be combined with the three basic skies 6.4 List of symbols 7. REFERENCES AND BIBLIOGRAPHY 7
9、.1 Luminance distribution 7.2 Zenith luminance 7.3 Horizontal illuminance from unobstructed sky 7.4 Radiance distribution 7.5 Others 7.6 References in Appendices 7.7 Further reading and average sky Page 1 2 2 2 4 5 5 6 7 7 7 8 9 9 9 9 II 11 14 21 23 25 25 26 27 28 29 29 30 IV COPYRIGHT International
10、 Commission on IlluminationLicensed by Information Handling Services CIE IL0 94 m 900bL45 0005052 75b CIE 110-1994 Spatial distribution of daylight - Luminance distributions of various reference skies Summary This technical report is a review of studies on various sky luminances and specification of
11、 reference skies, with a method of composing average sky and mean sky as an appendix. Several reference skies including the average sky and mean sky are given definitions and various studies on these sky luminances are introduced, with a bibliography, in three appendices. Rpartition spatiale du lumi
12、re de jour - Rpartition de luminance de plusieurs ciels de rfrence SOMMAI RE Ce rapport technique est une revue des tudes sur les luminances de diffrents ciels et sur la spcification des ciels de rfrence, avec en annexe une mhode de dtermination dun “average sky“ et dun “mean sky“. On donne la dfini
13、tion de plusieurs ciels de rfrence incluant le “average sky“ et le “mean sky“ et on prsente diffrentes tudes sur ces luminances de ciel, avec une bibliographie, dans trois annexes. Rumliche Verteilung des Tageslichts - Leuchtdichteverteilung verschiedener Bezugshimmel Zusammenfassung Dieser technisc
14、he Bericht ist ein berblick ber Untersuchungen ber verschiedene Himmelsleuchtdichten und Beschreibung von Bezugshimmelszustnden, mit einer Methode zur Zusammenfgung von mittlerem Himmel “average sky“ und mittlerem Himmel fr eine bestimmte Zeitdauer “mean sky“ als Anhang. Verschiedene Bezugshimmelszu
15、stnde, die sowohl den “average sky“ als auch den “mean sky“ beinhalten, sind angegeben. Definitionen und verschiedene Untersuchungen ber diese Himmelsleuchtdichten werden mit einem Literaturverzeichnis in drei Anhngen eingefhrt. V COPYRIGHT International Commission on IlluminationLicensed by Informa
16、tion Handling Services CIE 110 94 m 900b145 0005053 692 m CIE 110-1994 1. INTRODUCTION Although several kinds of average and mean skies have been proposed in Europe, USA and Japan since 1981, their definitions and the methods of composing them were not standardized. This Technical Committee, TC 3-09
17、, was formed at the CIE Amsterdam Session in 1983, and the aim of the committee was suggested in the minutes of the Division 3 Cambridge meeting in April 1984 as follows. “The aim is not to make a list of various sky situations, but to try to develop as few as possible sky standards between the two
18、skies already standardized: clear sky and overcast sky.“ According to this suggestion the terms of reference of TC 3-09 were decided as, “To study standard reference skies between the two skies already standardized, clear sky and overcast sky, and to propose a method of composing average and mean sk
19、ies.“ However, because of insufficient data and lack of time, it became difficult to propose standard skies (.e. standard intermediate skies) between the two already standardized skies by the time of the CIE Venice Session in 1987. Therefore, the purpose of our TC 3-09 was changed to presentation of
20、 a technical paper which would review studies on various skies, specify reference skies, and introduce a method of composing average sky and mean sky as an appendix. Also the two CIE Standard skies (Clear sky and overcast sky) are reviewed in the present publication, thus publication CIE 22-1973 is
21、now outdated and withdrawn. The standardization of reference skies between the two standard skies was left to a new technical committee, TC 3-15 (Standardization of intermediate sky luminance), which was formed at the CIE Venice Session in June 1987. In this report a references sky means a clearly d
22、efined sky to be used for daylighting design and calculation methods. For example, one reference sky is the uniform sky which has been used for a number of theoretical application and for certain design purpose. The skies treated in this report do not include direct sunlight, though the BRE average
23、sky developed by Littlefair consists of two components, direct sunlight and the sky I .3-1 , 1.3-3, I .3-4. (Numbers in square brackets mean reference numbers from Chapter 7. REFERENCES AND BIBLIOGRAPHY). In order to estimate annual energy consumption of electrical lighting, the effect of direct sun
24、light should be taken into consideration in calculating illuminance on the interior working plane, whether this is done for every weather condition or for a certain average condition. Hence, each standard sky luminance has to be combined with a standard direct sunlight illuminance. These items are t
25、o be decided in another technical committee in future, but a proposal is tentatively shown in 6.3 for reference. 1 COPYRIGHT International Commission on IlluminationLicensed by Information Handling Services CIE 110 94 W 7006145 0005054 529 = CIE I1 0-1 994 2. DEFINITIONS OF VARIOUS REFERENCE SKIES 2
26、. i Reference skies to be defined In this chapter the following five reference skies are defined. 1 CIE standard clear sky 2 CIE standard overcast sky 3 Intermediate sky 4 Average sky 5 Mean sky The first and second skies are already standardized by CIE in terms of the relative luminance distributio
27、ns. The third one might in the future be recommended as a CIE standard sky, or as a set of standard skies. A recommendation for more than one sky will be made only if absolutely necessary, and the number of skies will be as few as possible. The 4th and 5th skies are for specified application and wil
28、l not necessarily be recommended as CfE standard. 2.2 Three basic reference skies 2.2.1 CIE standard clear sky This is a “cloudless sky“ for which the relative luminance distribution was first described in Publication CIE 22-1973 I1.1-41 and has been standardized by the CIE 1.1-61. Absolute luminanc
29、e will be standardized in future. 2.2.2 CIE standard overcast sky This is a “completely overcast sky for which the ratio of its luminance in the direction at angle y above the I , I i I horizon to its luminance at the zenith is standardized 11.4-1, 1.1-61. Absolute luminance will be standardized , i
30、n future. 2.2.3 Intermediate sky This is a sky (or skies) for which the luminance of any given sky element will be defined for a given sun position under an intermediate weather condition (or conditions) which occurs between the CIE standard clear and overcast skies (see Fig.2.1). This luminance dep
31、ends on the solar altitude in the same way as does the CIE standard clear sky. The sun and aureole close to it are excluded from this luminance distribution. Absolute luminance and luminance distributions are to be defined for the CIE standard intermediate sky (or skies) in the future. 2.2.4 Weather
32、 conditions For design purposes, these reference skies may be taken to represent real skies under the following weather conditions: 1 Under the clear weather condition, adopt the CIE standard clear sky. 2 Under the overcast weather condition, adopt the CIE standard overcast sky. 3 Under intermediate
33、 weather conditions, which include hazy cloudy skies and partly cloudy skies, adopt an intermediate sky. It is proposed that these weather conditions, which will include as many intermediate weather conditions as there are intermediate skies, will be classified in terms that will enable the proporti
34、ons of time for which each reference sky applies to be determined within a defined time period for a chosen location and climate (see Fig.2.1). 2 COPYRIGHT International Commission on IlluminationLicensed by Information Handling ServicesCIE 110-1994 Clear sky Real skies Hazy cloud sky (Homogeneous t
35、urbid sky) Overcast sky Cloud-blue mixed Reference skies L CIE Standard clear sky* Standard intermediate skyiskies (to be defined) t CI E Standard overcast sky* Fig.2. I. Modelling to reference skies (* for which absolute sky luminance is to be defined) 3 COPYRIGHT International Commission on Illumi
36、nationLicensed by Information Handling ServicesCIE 110 94 H 900b145 O005056 3TL CIE 11 0-1 994 2.3 Reference skies for specified application 2.3.1 Average sky This is a sky for which time-average luminance of a sky element at an arbitrary position of the sky is defined for each hour of the day throu
37、ghout a typical year, for all weather conditions. This luminance depends on solar altitude alone in the same way as does the CIE standard clear sky. The sun and the aureole close to it are excluded from this luminance distribution. The period of averaging for this sky can be changed to a period othe
38、r than one year according to the specified application. 2.3.2 Mean sky This is a sky for which the time-average luminance of a sky element at an arbitrary position of the sky is defined for some specified duration (usually, the sum of working hours, for example, duration from 9:00 to 1700 of each da
39、y) throughout a typical year. Effects of the sun and of the aureole close to it are excluded from this luminance distribution. 4 COPYRIGHT International Commission on IlluminationLicensed by Information Handling Services3. CLEAR SKY AND OVERCAST SKY AS REFERENCE SKIES 3.1 Clear sky 3.1.1 Relative lu
40、minance distribution Expression of the CIE standard clear sky I .I-4, 1 .l-61 is one of the reference skies For practical purposes the sky luminance L, (y, y, 1;) at an arbitrary position P of the sky shown with y, 8O0. Pierpoint 1.2-10, 1.2-121 proposed a luminance distribution similar in form to t
41、he clear sky from measurements of partly cloudy skies, but the basis of the proposed equation was not clear. I 8 1 COPYRIGHT International Commission on IlluminationLicensed by Information Handling ServicesCIE 110-1994 5. AVERAGED SKIES FOR SPECIFIED APPLICATIONS 5. I BRE average sky Littlefair 1.3-
42、i proposed an average sky based on measurements of a wide range of real skies as an adequate model of sky luminance distribution in order to estimate internal daylight availability for energy use prediction. He developed the BRE average sky as a function of solar altitude, with a direct solar, a cir
43、cumsolar and a background diffuse component, making use of luminance data measured by Wegner I .2- I, 1.2-21. The BRE average sky by Littlefair was modified to fit southeast England and was developed to be suitable for interior daylight calculation 1.3-3, 1.3-4, 1.3-61. The average sky luminance dis
44、tribution is expressed as the following equation. LavBRE(yS,y,l;) = a exp (-4 140) + d (5 - 2 sin y ) / 3 a = 0,l + 0,42 y, - 0,7 sin (7,2 y,) d = ( 9/11 R )( 0,3 + 0,434 y, - 0,0042 y, ) kcd/m2J where y, y, i i vY I 30 I I I 60 I I 81 I I I I I I o 10 + YS tdegl Ys, max Fig. 6.5 Monthly mean hourly
45、 value of relative sunshine durafion, O, (ys) and ifs average, cy (ys,max IO“). (3) Example i) London (4 = 51 32“) 16.1-31 y, = 61,93“, k = 46,85 % from eq.(6.24), see Table 6.2 for oy (y,) i) Tokyo (Q = 35,65“) 16.141 y, =77,80“, = 44,9 %I, k = 58,13 % from eq.(6.24), see Table 6.2 for oy (y,) = 33
46、,9 %I, Table 6.2. Relative sunshine duration as a funcfion of solar altitude in London and Tokyo (6.24) (6.25) COPYRIGHT International Commission on IlluminationLicensed by Information Handling Services - CIE 110 94 900b145 0005071 608 D CIE 110-1994 6.2.3 Method of obtaining probabilities of occurr
47、ences of the three basic skies from the yearly mean value of Nakamura, Oki et al. 5.1-4 developed a method of estimating the probabilities of occurrences of the three basic skies from meteorological observation data recorded at 8 stations in Japan during 4 years from 1979 to 1982. Using the results
48、from this study the monthly mean values of probabilities, Pei, Pi, and Po, %I were related to the monthly mean values of r.s.d. om %l. The relations are shown as Fig.6.6(a), (b) and (c) and were fitted by three curves using non-linear regression to give the following equations I .3-7, 5.1-51. relati
49、ve sunshine duration, oy fci = 5,689 I ( 1,054 - 0, I 100 ) - 5,397 %I (6.26) Pi, = 100 - 5,689 / ( 1,054-0,/ 100) - 78,629 / ( 0,551 + O, / I00 ) + 56,091 Po, = 78,629 / ( 0,551 + O, / 100 ) - 50,694 “/.I “/.I (6.27) (6.28) However, they commented that these equations must be re-examined when the rsd. is higher than 70%. If in these relations we can substitute the monthly mean hourly value of r.s.d., oh(ys), dependent on the solar altitude y, for om (see Fig.6.6(d), it is possible that the three
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