Footprint, at grade or below grade?

Hi! I have a question similar to the one posted on Nov 18 2013 below. I have a much larger LEED boundary below grade (parking garage) than above grade (office building) I will show this both in a site plan and in a section to make it clear for reviewers. But my question, which is the building footprint? The office at grade footprint? Or the underground garage footprint? (The garage will also be serving a neighboring property with parking space through off-site parking for that building).The hardscape above the garage, outside the office is not included in the property boundary. /Maria