As if you weren't worrying enough already, here's a little something that I ran across through monitoring activity on the American Society of Healthcare Engineers discussion boards:  

Greetings,

Hi to all:

Hi all, 

Hi to all,

Hello,

I am working on Football Club Academy project based on LEED NC 2009 and AGMBC 2011.

Hello, I have never documented this credit by using the shading option from existing tree canopy. I understand you'll need to calculate shaded area from each tree on June 21 at 10, 12, and 3pm.

We have a campus site site with areas, outside of construction limits, that contain many mature shade trees with turf grass underneath.

We are using the shadow of the trees canopy to comply with the credit. When calculating the average shadow of three times a day, part of this is outside the site boundary.