Insulating my shop

[BlueKnife]

I have trusses. These foam inserts are called rafter vents, that is the only time I mentioned rafters.

You said that you were going to use batt insulation "between the rafters". Anyway, are you planning to put the batts between the top chords or bottom chords of the trusses? Ideally, the insulation should be between the bottom chords and then a vapor barrier should be installed under that before the ceiling. This allows plenty of airflow above the insulation. You'll also want to make sure that your ridge is vented properly. If it isn't, eave vents won't help.