Gross Lighted Area - ASHRAE 90.1-2007

This topic was previously posted under EAp2, but was not getting any responses; this seems like the more relevant location anyways: I'm encountering difficulty in documenting the minimum 10% lighting reduction. This is due to some uncertainty in the definition of gross floor area, per ASHRAE 90.1-2007. The definition is found here: http://www.gbci.org/main-nav/building-certification/resources/fees/curre... Per this definition, and from users' experience, does this exclude spaces with a headroom less than 7.5'? What if these areas are part of a larger space that has heights in excess of 7.5'? Thank you for your help!