PI Notification Trigger based on Batch event

Hello:

I'm trying to figure out how to calculate the average of a tag at the end of each of our production runs.  We use PIBatch to generate our batches.  We collect the process tag (Pressure) throughout the batch.  At the end of the batch, I'd like to e-mail this value (average), via PI Notifications.  Thoughts?

Using AF2012, and PI Notifications 2012, and PIBaGen.

Thank you!