Average daylight factor for the ISO/CIE Standard General Sky

Alshaibani, Khalid

doi:10.1177/1477153515572939

Cited by 12 publications

(7 citation statements)

References 22 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…alternative daylight prediction model is that DF does not consider the impact of orientation [28], building location [29] daytime and sky conditions [30][31][32], since the CIE reference sky is overcast.…”

Section: Acronymsmentioning

confidence: 99%

Improvement of Daylight Factor Model for Window Size Optimization and Energy Efficient Building Envelope Designs

Mebarki

Djakab

Mokhtari³

et al. 2021

Journal of Daylighting

View full text Add to dashboard Cite

Based on a new approach for the prediction of the Daylight Factor (DF), using existing empirical models, this research work presents an optimization of window size and daylight provided by the glazed apertures component for a building located in a hot and dry climate. The new approach aims to improve the DF model, considering new parameters for daylight prediction such as the orientation, sky conditions, daytime, and the geographic location of the building to fill in all the missing points that the standard DF, defined for an overcast sky, presents. The enhanced DF model is considered for the optimization of window size based on Non dominated Sorting Genetic Algorithm (NSGA II), for heating and cooling season, taking into account the impact of glazing type, space reflectance and artificial lighting installation. Results of heating and cooling demand are compared to a recommended building model for hot and dry climate with 10% Window to Wall Ratio (WWR) for single glazing. The optimal building model is then validated using a dynamic convective heat transfer simulation. As a result, a reduction of 48% in energy demand and 21.5% in CO2 emissions can be achieved. The present approach provides architects and engineers with a more accurate daylight prediction model considering the effect of several parameters simultaneously. The new proposed approach, via the improved DF model, gives an optimal solution for window design to minimize building energy demand while improving the indoor comfort parameters.

show abstract

Section: Acronymsmentioning

confidence: 99%

Improvement of Daylight Factor Model for Window Size Optimization and Energy Efficient Building Envelope Designs

Mebarki

Djakab

Mokhtari³

et al. 2021

Journal of Daylighting

View full text Add to dashboard Cite

show abstract

“…In other words, we should first predict and evaluate the sky luminance distribution to accurately predict indoor daylight illuminance. As sky luminance can vary considerably, we should have an accurate standard to derive an objective conclusion [13].…”

Section: Background and Purposementioning

confidence: 99%

“…where E p,r = indoor horizontal reflected illuminance at P point (lx), τ w = visible light transmittance, L = center of window luminance (kcd/m 2 ), z = the distance between the window and P point (m), h w = window height (m) and W w = window width (m). Equations (12) and (13) [31,32] are direct component equations, which modify the incidence angle through the window:…”

Section: Suggestion Of the Daylight Prediction Equation Using The Delmentioning

confidence: 99%

Development of Sky Luminance and Daylight Illuminance Prediction Methods for Lighting Energy Saving in Office Buildings

Kim

2019

Energies

View full text Add to dashboard Cite

Accurately predicting indoor illuminance from daylight during the early stages of building design is an important factor in saving energy and the costs associated with lighting. The objective of this study was to predict sky luminance distribution using the Commission Internationale de l’éclairage (CIE) standard sky model, and propose a method that can be used to predict indoor illuminance. Results obtained from the proposed prediction method were compared and verified with simulation values obtained by Desktop Radiance. From the CIE overcast sky, the zenith/horizon ratio was 3:1. From the CIE clear sky, the luminance value was highest around the sun. In contrast, the luminance value was lowest in the opposite direction of the sun when the angle between the sun and sky elements was 90°. In addition, this study suggested an indoor illuminance prediction method by applying the effects of sky luminance, direct sunlight, and wall reflection elements. When the proposed equation’s calculation results were compared with Desktop Radiance simulation’s value in overcast and clear sky, all statistically analysis (R2, MBE, Cv(RMSE), t-value, p-value) satisfied each standard and showed high correlations. Consequently, it was established that the predicted indoor illuminance obtained from the proposed prediction method was accurate and can be used to predict the level of indoor illuminance. The results further revealed that it is possible to calculate indoor illuminance when installing blinds, by substituting variable values of visible light transmittance (VLT).

show abstract

“…In 2018, European standard 25 EN17037, Daylight in Building, was established and a correlation between DF and average VDF was one of the main themes of the work conducted by Sprah and Kosir. 25 Currently, PDF, 26,27 ADF 28,29 and VDF 30,31 are still adopted in many investigations for evaluating daylighting designs. Studies included DF estimation at an early design stage to reduce building energy use, 32 quantifications of daylight and outdoor comfort.…”

Section: Introductionmentioning

confidence: 99%

Simple correlations between point daylight factor, average daylight factor and vertical daylight factor under all sky conditions and building design implications

Chen

et al. 2022

Indoor and Built Environment

View full text Add to dashboard Cite

The customary method for calculating daylight illuminance in a building is the daylight factor approach, which is assumed under the conventional overcast sky. However, such an approach is not flexible enough to predict diffuse illuminance in the presence of non-overcast skies. The daylight factor is invariant to building orientation and cannot take realistic and time-varying climatic conditions into account. Daylight in buildings is estimated using computer simulation techniques. However, full-scale computer simulations can be costly and time-consuming. Practitioners welcome simple calculation aids established via comprehensive analysis. Such easy tools would give building professionals and students basic and concise insight into the independency of different daylight parameters. Recently, daylight factor calculations have been extended to non-overcast skies. It means that the daylight factor approach can be a dynamic metric. This paper presents the calculation of the point daylight factor, the average daylight factor and the vertical daylight factor under all sky conditions, as well as building façade design implications. The performance of the three types of daylight factor for a typical room at various scattering angles is elaborated and evaluated; simple correlations between them are developed.

show abstract

Average daylight factor for the ISO/CIE Standard General Sky

Cited by 12 publications

References 22 publications

Improvement of Daylight Factor Model for Window Size Optimization and Energy Efficient Building Envelope Designs

Improvement of Daylight Factor Model for Window Size Optimization and Energy Efficient Building Envelope Designs

Development of Sky Luminance and Daylight Illuminance Prediction Methods for Lighting Energy Saving in Office Buildings

Simple correlations between point daylight factor, average daylight factor and vertical daylight factor under all sky conditions and building design implications

Contact Info

Product

Resources

About