Using a Light Shelf for EA and EQ LEED Credits

Photo Credit: AADL.org

Incorporating a light shelf into your building design is a great way to make progress on EA and EQ LEED credits.  Basically, a light shelf is an architectural element placed overhead that redirects light deeper into a building than it would otherwise travel, thus reducing the need for artificial light.

Interior vs. Exterior:  A light shelf can be placed on the interior or  exterior of a building or, ideally, extend on both sides of the window.  However, in some urban applications with zero lot line conditions the shelf can only be interior.  While this, to some extent, diminishes the benefits it certainly doesn’t negate them.  The real loss is not as much in the volume of reflected light into the space as much as it is in the glare reduction on the lower part of the window system.

Limitations: There are, however, some limitations.  A shelf generally should be placed on the south elevation to take advantage of maximum sunlight exposure.  If your building doesn’t have a southern exposure, the benefits can be significantly diminished, especially on a northern exposure.  Also, a relatively high ceiling height is required for optimum benefit.  Depending on the source, you’re looking at 9.5 to 10 feet.  Lastly, in a geography with a limited number of sunny days, the overall benefit is reduced.

The most valuable aspect of the light shelf is that it is a passive solar technology, requiring almost no maintenance and has zero moving parts.  As with any ‘green’ technology or design element, the simpler the solution and the less ongoing occupant interaction required, the better.

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