I'd close it in the winter and save a few pennies.

It will be the corner of the house, so 2 outside walls. I'm not too worried about it being 2 outside walls though. I think our house is pretty well insulated, as we haven't had issues like that before. We live in North Carolina.

We have an HVAC vent in our roughly 6x6 pantry and a grille over the door. Our architect recommended this setup and I didn't disagree after reading the thread below and the 2007 thread linked in the first post. We've been in the kitchen only a couple of week now, so I can't comment on whether it's working or not.

Here is a link that might be useful: Pantry ventilation threads

As long as there's a return (vent over or in the door, for example) it's a good idea. You want steady temperature in food storage areas.

See if there's another place he can put the vent.
Or you could plan shelving that runs above the vent.

We will check into the return above the door. Thanks for that suggestion!

CEFreeman: What do you mean by another place he can put the vent? It will be on the floor somewhere. We will have shelving that runs above the vent, but I'm just concerned about losing the floor space to put a pail (with food in it) or something like that that we might want to store on the floor. Thanks for taking the time to reply!

Why does the vent need to be on the floor? If the main runs are in the basement, rectangular duct can run through an interior stud bay to up higher in the room if you need the floor storage. But, it will have to exit the stud bay somewhere, so figure out where that might be best accomplished. It's the same with a return. Ideally, it should be located across the room from the supply, but there is some leeway in placing it. Talk to your HVAC professional here about your needs. However, ventilation of a pantry is a MUST, so don't skip it.

We have vents in our pantry and all walk-in closets/storage rooms/closets. If you have stone or hardwood floors, they will sit off the floor enough - you don't need a return in the pantry. You can close/open vent whenever you want.

The main level vents are on floors. The lower level vents are in the ceiling. Wall vents have to have a deeper wall depth (duct has to turn, flow correctly, etc).

I would definitely add the vent. As long as it doesn't get too hot in the winter in there, your furnace should keep the humidity inside relatively low. Good for almost all food storage.

I added a vent in our pantry and I hate it. In the winter all my chocolate melts and it gets really hot in the small space. I wish I didn’t add one there. Bye bye KitKat

I put a magnetic cover over the pantry vent in the winter and remove it in the summer, and the chocolate stays snappy year-round! :)