Properly Cooling A Small Telecom / Sever Closet ?

Hi –

I have a small office client, and he wants to put a small server rack in his telecom closet. The rack is not that big, but I think I should have some kind of cooling in there. Hooking up to the buildings HVAC is going to be REALLY difficult –

I was thinking just putting in a fan / duct and exchanging air to the common office area outside the closet, but what happens, say in the winter when the building’s AC isnt really running? I was affraid it might not be sufficient

Can anyone suggest a solution to this? Perhaps some small rack mountable AC unit? Or would exchanging ambient office air be enough?

Thanks –
Mikey