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RESEARCH SUMMARY DETAIL

Vertical Shades and Indoor Daylight Quality

Author's Title: A Mini-Scale Modeling Approach to Natural Daylight Utilization In Building Design
Author(s) Name: C. L. Cheng, C. L. Chen, C. P. Chou, and C. Y. Chan
Year of Publication: 2007
Search Related Keywords: Door, Window, Curtain Wall, Skylight, Glazing  Energy Efficiency  Lighting/Daylighting Design 

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Design Issue
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This experiment used a model to examine how vertical shading devices used under a variety of conditions affect the interior daylighting performance in buildings.


  • While direct sunlight often causes glare and overheating, diffused sunlight may be inadequate, especially in the core of the building. Reflected sunlight is stronger than diffused light and can be spread further into the room.
  • Certain daylight techniques (e.g., bioclimatic roofs, light pipes) for the building core are limited to only the top floor. Little research has been done on the use of vertical shading devices and daylighting.
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Design Criteria
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Author Identified:
  • Use vertical shading devices to redirect light into a space.
  • Consider using a mini-scale model and the measurement methods detailed in the article when designing a space that will utilize vertical shading devices to ensure optimum shading and light characteristics.

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Key Concepts
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  • Reflective shading devices redirected light into a space and illuminated further into a room.
  • The vertical shading devices redirected more light as the depth of the vertical shading devices increased.
  • The measured illuminance decreased when the relative azimuth angle increased.
  • As the ratio of the area of the window to the area of the wall increased, the stronger the daylight reflected throughout the room.
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Research Method
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  • A rectangular, scaled model (1:20) with 15 photometers was set up. The model was 6 m x 6 m x 3 m and the photometers were placed at equal intervals, separating the model into 15 data collecting areas. There were four changeable walls in the model, each with a different window size, and five different depths of shading devices.
  • The area of the windows, the altitude and azimuth of the sun, and the depth of the shading devices were changed throughout the experiment.
  • data was collected under clear sky conditions, with less than 30% clouds.
  • ANOVA and regression analysis were used to analyze the data.
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Limitations
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  • The author did not identify any limitations.
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Commentary
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A review of literature was conducted on techniques for modeling daylight availability and for measuring the behavior of daylight in a room. Diagrams of the experiment, tables and graphs of data, and a chart of the experimental process were included.



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Adapted From
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Author(s): C. L. Cheng, C. L. Chen, Department of Architecture, National Taiwan University of Science and Technology, Taipei, Taiwan; C. P. Chou, Department of Architecture, TamKang University, Taiwan; and C. Y. Chan, Department of Architecture, Hwa Hsia College of Technology and Commerce, Taiwan
Article Title: A Mini-Scale Modeling Approach to Natural Daylight Utilization in Building Design
Publisher: Elsevier
Publication: Building and Environment
Publication Type: Refereed Journal
Date of Publication: 2007
ISSN: 0360-1323
Volume: 42
Issue: 1
Pages: 372-384