I'm actually quite curious about this myself, as I'll be arriving in DUB one week from today fairly early and would love to be able to take a shower.

I noticed in the lounge FAQ (http://www.flyertalk.com/forum/aer-l...s-lounges.html) that in the section describing access rules, they add that "UA J passengers are permitted access (outbound)", suggesting that UA passengers are allowed outbound but not inbound access. It would seem silly to mention this if other passengers were also prohibited from inbound access.

I just tried calling the hotline and they're closed - I'll try again in the morning, but I don't see, based on what I'm reading, why they wouldn't let you through to use the lounge. There wouldn't be any crossing between T1 or T2, and you'd presumably need to cross immigration anyway to exit anyway. I feel like most airlines allow access to normal lounges on arrival, so I'd be surprised of Aer Lingus didn't offer the same.

What do they check there when you cross back into the transit area? Do they allow you to simply walk through, or do they look at your ticketing information?