I refuse to go off on tangents unrelated to the OP's post, or engage in strawman arguments with you any longer. No one is complaining about being uncomfortable due to the cold, except you.
UPS has a contractual obligation to attempt to heat the building. They are not fulfilling that obligation, thus the OP should grieve it. Yes, it is possible the heat is broken. UPS then has an obligation to fix it as soon as is reasonable. Regardless of whether the heat is off or broken in the OP's hub, other posters have inferred that UPS purposely keeps the heat off in their hubs. This is improper and should be grieved. How effective the heat is, if at all, whether drivers are colder, no matter what wardrobe the OP has access to, how new the lines in his yard are, how well it's plowed, or how bright it is, is of no consequence.
As a Teamster, if you see a blatant contract violation being committed by UPS, it is your job to grieve it, for the good of everyone.