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The New Method To Calibrate Iso/cie General Skies modelled In Artificial Skies Light & Engineering Vol. 29, No. 1

Light & Engineering 29 (1)

Volume 29
Date of publication 02/27/2021
Pages 11–20

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The New Method To Calibrate Iso/cie General Skies modelled In Artificial Skies Light & Engineering Vol. 29, No. 1
Articles authors:
Stanislav Darula, Richard Kittler

Stanislav Darula, Associate Professor, Ph. D. At present, he is senior researcher at Institute of Construction and Architecture, Slovak Academy of Sciences. His professional interest is focus on the research of daylight phenomena, daylight availability, daylight standardization and daylight design in buildings. He is national member of CIE Division 3, CEN TC169/WG 11 and participated in the elaboration of the European standard Daylight of buildings. As a member of the presidium of the Slovak Lighting Society and member of The Association of Slovak Scientific and Technological Societies as well as The Slovak Chamber of Civil Engineers he contributes in the activities in the research and popularization of illuminating engineering. At the Faculty of Civil Engineering of the Slovak University of Technology he is an external lecturer in the course of Building Physics

Richard Kittler graduated in 1953 with honours in Building Science as Diploma Engineer at the Slovak Technical University, Faculty of Construction and Architecture and soon started his postgraduate studies at the Institute of Construction and Architecture of the Slovak Academy of Sciences (ICA SAS) and received in 1957 a Ph.D. and in 1966 D. Sc. degree at the Czech University of Technology in Prague. Since 1953 he is employed as a Scientist, later principal Scientific Officer in ICA SAS at Bratislava in building physics with special regard to daylight research. Best known are his studies of sky luminance patterns in nature and in artificial skies as well as their standardisation for calculation and simulation purposes, now also in the CIE/ISO Standard. His long-term involvement in CIE activities during 1959–2007 was appreciated by the CIE Distinguished Services Wyszecki Award for Fundamentals within the Beijing CIE General Session. In 2002 he was elected to a membership of the European Academy of Sciences. His team has published a seminal book “Daylight Science and Daylighting Technology” Springer, New York, 2012, summarising basic knowledge in this specific subject

Abstract:
Recently sky luminance distributions under fifteen ISO/CIE sky types were standardised in relative terms, i.e. all elementary sky luminance are normalised by the zenith luminance in nature. However, these standard sky luminance patterns can be characterised also in their physical units, see in CIE215:20014 which can be reduced by suitable intensity scales to simulate the very high natural sky luminance in laboratory under artificial sky domes. For the design of the electric illumination system of the artificial sky the appropriate zenith luminance for each sky type has to be derived respecting the indicatrix and gradation functions of each sky type. Thus, the sky patterns simulated in the artificial sky can be calibrated either by luminance measurements or by analysing fish-eye photos taken from the sky centre showing the smoothness and gradual changes of homogeneous sky type luminance patterns. The sky luminance images can be utilised to proceed with the adjustment or dimming of the LED electrical system to the final calibration check containing zenith luminance and exterior illuminance in the second calibration step.
References:
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3. Darula, S., Kittler, R. The new generation of an artificial sky: simulating various overcast sky conditions// Proc. of the European Lighting Conference Lux Europa 2017. Ljubljana: Lighting Engineering Society of Slovenia, 2017, pp. 401–405.
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8. International Standard Organisation: ISO Standard 15409:2004 Spatial distribution of daylight – CIE Standard of General Sky. Geneva: ISO, 2004.
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