Performance Analysis and Guidelines for Lightshelves

Open Access
Kim, Ga Young
Graduate Program:
Architectural Engineering
Master of Science
Document Type:
Master Thesis
Date of Defense:
November 10, 2009
Committee Members:
  • Richard George Mistrick, Thesis Advisor
  • roller shades
  • daylighting
  • computer simulation
  • internal and external lightshelf
  • lighting energy
This paper focuses on the performance of lightshelves in terms of daylight illuminance distribution, sunlight penetration, and lighting energy use. Lighting software, AGI32 and DAYSIM 2.1, are used to develop a better understanding of design performance as well as guidelines for the effective use of lightshelves. When only an internal lightshelf is used, there are more shading hours required for the lower window so that occupants have very few opportunities to enjoy a view outside; in addition, the daylight levels are low. However, a combination of internal and external lightshelves helps to increase the daylight illuminance level, as this combination reduces the shading hours for both the view windows. Lightshelves with properly controlled roller shades help to reduce the amount of lighting energy required; however, a deep lightshelf barely reduces the lighting energy used in a space facing 60 degrees east. This performance analysis of lightshelves aims to present results from which valuable design guidelines can be extrapolated for manufacturers and designers to apply.