Analysing the impact of reflectance distributions and well geometries on vertical surface daylight levels in atria for overcast skies

This study investigated the impacts of different diffuse reflectance distributions and well geometries on vertical daylight factors and vertical internally reflected components in atria. Two forms of reflectance distribution patterns of wall surface were examined: horizontal and vertical reflectance band variation. The square atrium models studied have a broader WI range of 0.25–2.0, which represent shallow, medium and high atria. Radiance, a powerful package based on backward ray tracing technique, was used for the simulations of vertical daylight levels. The results show that different reflectance distributions of square atrium walls do have an impact on the vertical daylight factors and vertical internally reflected components under overcast sky condition. The impact relates to the orientation of the band with different reflectance distributions on the wall. Compared with the vertical band surface, the horizontal band surface has a much more complicated effect. The horizontal distributions of the reflectances significantly affects the vertical daylight levels at the locations more than 30% atrium height on the wall. For an atrium with a height more than 1/2 the width, the effect tends to increase with the increasing well index. The vertical distributions of the reflectance, nevertheless, do not substantially take effect on the vertical daylight levels in atria except for some special reflectance distribution patterns.

[1]  Morad R. Atif,et al.  Daylight availability in top-lit atria: prediction of skylight transmittance and daylight factor , 2000 .

[2]  S. Sharples,et al.  Surface Reflectance Distributions and their Effect on Average Daylight Factor Values in Atrium Buildings , 2004 .

[3]  J. C. Wright,et al.  Illuminace in atria: Review of prediction methods , 1998 .

[4]  J. Mardaljevic.  Daylight simulation : validation, sky models and daylight coefficients. , 1999 .

[5]  Steve Sharples,et al.  Daylight in Atrium Buildings: A Critical Review , 2007 .

[6]  S. Sharples,et al.  Reflectance distributions and atrium daylight levels: a model study , 1999 .

[7]  S. Sharples,et al.  Reflectance distributions and vertical daylight illuminances in atria , 2004 .

[8]  P. R. Tregenza.  Daylight attenuation in top-lit atria , 1997 .

[9]  P. Littlefair.  Daylight prediction in atrium buildings , 2002 .

[10]  John Mardaljevic,et al.  Validation of a lighting simulation program under real sky conditions , 1995 .

[11]  S. Samant,et al.  Daylighting in atria: The effect of atrium geometry and reflectance distribution , 2007 .

[12]  Christoph F. Reinhart,et al.  Efficient calculation of daylight coefficients for rooms with dissimilar complex fenestration systems , 2008 .

[13]  Usha Iyer-Raniga.  Daylighting in Atrium Spaces , 1994 .

[14]  R. Cole.  The effect of the surfaces enclosing atria on the daylight in adjacent spaces , 1990 .

[15]  Øyvind Aschehoug.  Daylight in glazed spaces: Daylight conditions in long glazed streets examined with physical models in an artificial sky and computer calculations , 1992 .

[16]  J. Scartezzini,et al.  Daylight factor prediction in atria building designs , 2004 .

[17]  Mohamed Boubekri.  The Effect of the Cover and Reflective Properties of a Four-Sided Atrium on the Behaviour of Light , 1995 .

[18]  S. Sharples,et al.  Computational simulations for predicting vertical daylight levels in atrium buildings , 2009 .