Uncertainty of daylight illuminance on vertical building façades when determined from sky scanner data: A numerical study

Kómar, Ladislav; Kocifaj, Miroslav

doi:10.1016/j.solener.2014.09.010

Cited by 9 publications

(8 citation statements)

References 15 publications

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“…Both the RMSD and the MBD values are recorded in Table 5 and, as can be appreciated, are comparable to those obtained for horizontal diffuse illuminance. It can, therefore, be concluded from this study that the use of the sky-scanner measurements, to determine the diffuse illuminance on any horizontal or tilted surface, had an intrinsic RMSD due, mainly, to the technical specifications of the experimental device, near 30%, agreeing with other works [11]. As has been previously stated, when CIE standard classification is available, the sky luminance distribution can be obtained from Equation (11), and Equations ( 7)-( 10) can be applied to calculate L dh , L dv and, therefore, VSC.…”

Section: Comparative Study Of the Different Approaches To Obtain The Vscsupporting

confidence: 90%

“…A fundamental step towards building design that illuminates interiors with daylight is the compilation of information on daylight availability outside the building. Illuminance on vertically oriented surfaces is, therefore, important for modeling the daylight availability, especially for high-rise buildings with substantial areas of glazed surfaces [11]. Solar radiation data on vertical surfaces can also be used to evaluate the performance of Building Integrated Photovoltaics (BIPV), because the vertical facades of modern cities occupy larger areas than roof surfaces and usually present better maintenance conditions for photovoltaic panels [12].…”

Section: Introductionmentioning

confidence: 99%

“…Global and diffuse outdoor illuminance on a horizontal surface and vertical global illuminance on the four (north, east, south, and west) cardinal orientations have been used to compute the VSC. However, as experimental data of L dv and L dh are scarce, different alternatives are used to calculate VSC [11,17,20].…”

Section: Introductionmentioning

confidence: 99%

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Evaluation of the Vertical Sky Component without Obstructions for Daylighting in Burgos, Spain

et al. 2020

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Daylight availability knowledge is the first step for an energetic and visually efficient building and city design. It can be estimated with the Vertical Sky Component (VSC), which is defined as the ratio of the vertical diffuse illuminance over the unobstructed horizontal diffuse illuminance, simultaneously measured at the same point. These illuminance magnitudes are obtained from luxmeter measurements but these data are scarce. Alternatively, VSC can be obtained from prior knowledge of the sky illuminance distribution, which can be measured with a sky scanner device or by reference to the CIE (Commission Internationale de L’Éclairage) Standard classification for homogeneous skies. Both approaches are compared in this study. The coherence of the results obtained for the four cardinal orientations are analyzed by applying classical statistical parameters and luxmeter measurements as references for the results. The measurement campaign was completed between September 2016 and January 2019 in Burgos (Spain), as representative case study and specific contribution of this work. It was observed that the VSC values were higher than 100 in many cases: 21.94% for the south- and 33.6% for the east-facing vertical surfaces. The study highlights the good daylighting conditions in Burgos, mainly due to the predominance of clear skies over much of the year. This fact implies high daylight availability that, with efficient city planning and building design, could potentially lead reduction energy consumption of buildings, improvements in visual comfort, and the well-being of occupants.

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Section: Comparative Study Of the Different Approaches To Obtain The Vscsupporting

confidence: 90%

Section: Introductionmentioning

confidence: 99%

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Evaluation of the Vertical Sky Component without Obstructions for Daylighting in Burgos, Spain

et al. 2020

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“…It can reach up to 20% in a horizontal illuminance and up to 50% in a vertical illuminance which is important in daylight availability on the building facades with windows (Kómar and Kocifaj, 2014). To get more accurate results a smaller field of view and thus a higher number of scanned elements is required what on the other side extends a scanning time and causes loss of information under rapidly changing sky conditions.…”

Section: Discussionmentioning

confidence: 99%

Data regression on sphere for luminance map creation from sky scanner measurements

Petržala

Kómar

2015

Solar Energy

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“…For instance, the area of the whole hemisphere is 2π R 2 , where R is the artificial sky radius, and the solid angles of a number of round sources cover a smaller area. Even closely placed circular sources, due to their solid angles, will cover the whole hemisphere only in a percentage of the whole hemisphere area as documented in Kómar and Kocifaj [2014]. Nevertheless, Tregenza's [1987] subdivision scanning system of 145 circular solid angles cannot be misused to imitate the sky lunes by spot circular reflectors because the whole luminance sky pattern is reproduced only to 60%-70%.…”

Section: Discussion Of Possible Errorsmentioning

confidence: 99%

A Methodology for Designing and Calibrating an Artificial Sky to Simulate ISO/CIE Sky Types with an Artificial Sun

Darula

Kittler

2014

LEUKOS

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Artificial skies are now commonplace in laboratories for daylighting studies in university schools of built environment studies. However, these research and educational devices are often not used to their full potential because they are not calibrated to model even location-specific International Oganisation for Standardisation (ISO)/CIE sky types. Nevertheless, sky luminance patterns and parallel sunbeam produced by an artificial sun in a sky simulator are required for realistic physical modeling. These facilities must be designed and calibrated in welldocumented protocols to achieve the scale ratios that proportionally model real outdoor skylight and sunlight conditions. Such exacting tasks can be accomplished by respecting several technical imperatives that this article was written to elaborate and discuss.

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Uncertainty of daylight illuminance on vertical building façades when determined from sky scanner data: A numerical study

Cited by 9 publications

References 15 publications

Evaluation of the Vertical Sky Component without Obstructions for Daylighting in Burgos, Spain

Evaluation of the Vertical Sky Component without Obstructions for Daylighting in Burgos, Spain

Data regression on sphere for luminance map creation from sky scanner measurements

A Methodology for Designing and Calibrating an Artificial Sky to Simulate ISO/CIE Sky Types with an Artificial Sun

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