Are you talking about a play PEN or a play YARD, those are two very different things.
A playpen is good for short term, need to do the laundry, need to pee, sort of situations. A play yard, is larger, allows them to roam in a safe and contained environment for longer periods of time.
I don't see an issue with either one of those things, as long as they are used in moderation and not as a babysitting tool.
I don't know if you mean a pack'n'play, but you could just stash it closed somewhere and open it/stick him inside while you run downstairs. What I normally do is wait for nap time because I couldn't be bothered by all of that. 1 year olds are tough. They're mobile, but they don't have any sort of logic. lol So they're climbing things .. like the kitchen table.. and chewing on cat poop and electrical wires when you aren't looking. If my 1 year old wasn't strapped down in some way, I wouldn't feel comfortable leaving him for even 5 minutes.
Granted my youngest is super ... uh ... toddler-ish. :D He gave me a run for my money. Even when I'm in the room with him, he still manages to get in big time trouble.
Anyway.... You get the idea. :) Good luck!