Daylight measurement data: Methods of evaluation and representation

Abstract

The International Daylight Measurement Programme will generate a large amount of data from distinct locations worldwide. To ensure comparability of results, data must be identified uniquely and standardisation of data analysis including the determination of derived quantities is necessary. A number of formulae are proposed for the normalisation and analysis of direct beam, global and diffuse irradiances and illuminances and sky luminance distributions. Graphical representation of results is discussed and a graphical approach, the P-G-D diagram, is put forward as a solution for irradiance and illuminance data presentation.

A review of daylight illuminance determinations and energy implications

“…This is of particular interest when considering a point in a deep plan side-lit room which will only receive vertical daylight from a certain part of the sky. Sky luminance distributions are less frequently measured than daylight illuminance [66]. In general, sky condition can be categorized into overcast, partly cloudy, and clear sky type [67].…”

“…Previously, a range of 15 standard skies based on detailed analysis of selected luminance scans measured in Berkeley (37.6°N, 122.4°W) during 1985-1986, supplemented by data from scans recorded in Tokyo (35.8°N and 139.8°E) and Sydney (33.9°S and 151.2°E) during 1992 were proposed [66]. The set of standard skies covers the whole probable range of skies in the world.…”

Comparison between winter and summer sky-luminance distribution in Central Europe and in the Eastern Mediterranean

“…Kittler and Darula, 2000), (ii) 0oE vg p1:2eE v0 sin g s ; where E v0 ¼ 133:8 klux is the extraterrestrial illuminance, called, illuminance constant (Kittler et al, 1992;CIE, 1994), (iii) 0oE ed p0:8eE e0 sin g s ; (iv) 0oE vd p0:8eE v0 sin g s ; Thus, for each set of observations, the ratio L vz =E vd is estimated and compared to the theoretical L vz =E vd values of the 15 curves for the current solar altitude, g s : Then, each observation is classified in one of the 15 sky standards, only when the measured value of the L vz =E vd ratio lies inside a zone of AE2:5% around the value on the theoretical curve. The case that one observation may be classified in more than one sky standards, due to convergence and intersection of the curves, has also been considered.…”

Parameterisation of the Four Half-Day Daylight Situations

“…The International Commission on Illumination (C.I.E) in its Technical Committee TC 3-08 for Daylight initiated in 1983 the so called International Daylight Measurement Programme (IDMP). This programme was officially launched by the CIE President Bodmann (1991) and several CIE IDMP stations were established world-wide and now relatively long-term regular data are available for studies and analysis (Kittler et al, 1992). Although some daily courses served to characterise luminance sky patterns and local daylight climate, there are possible more detail analysis of half-day situations with relation to sunshine duration, cloudiness and turbidity influences parametrised.…”