I agree with both posters.
I wouldn't get too worried. Goldfish, unlike tropical fish, can withstand some pretty fridgid temperatures. Goldfish that live oudoors frequently tolerate temperatures below 40 degres F. They are domesticated descendants of the carp, a fish that lives in the wild in streams and rivers and has to live in ice-cold water all the time.
You do want to avoid water that is beginning to freeze, but hopefully the building won't get that
Now tropicals on the other hand must have warmer temperatures to be comfortable. Even bettas have trouble tolerating a power outage during the winter.
Just goes to show how hardy those little goldies are!