Optical Light Shelves

A passive optical light shelf relies on reflective materials and engineered profiles to redirect incident sunlight uniformly onto the ceiling and typically requires no adjustment over the year. The systems are designed to be installed in the upper clerestory portion of the window and must control specular sunlight and surface brightness to avoid glare. In some instances, the same system can be coupled with a plenum-installed light pipe or skylight for greater efficiency in core spaces. Research has been conducted to develop new designs and evaluate commercially-available daylight-redirecting technologies.

Falsecolor luminance maps of the rear wall in the Advanced Windows Testbed.  A passive optical lightshelf (POL) placed in the clerestory portion of the window redirects sunlight to the rear wall of the test room (bright yellow region on the upper portion of the rear wall) while the reference condition (white venetian blind) distributes its flux on the ceiling next to the window.  The POL can displace lighting energy use in areas further from the window wall.