Three crews arrived about 9am at the Castle St premises, which comprises four coal-fired steam boilers to supply steam and hot water to Dunedin Hospital and the University of Otago.
Fire and Emergency New Zealand senior station officer Peter Brosnan said a ladder truck was later called help to firefighters locate the source of the smell via the roof, which ``took a bit of finding''.
The source of the smell was later found to be a small smouldering fire between two coal hoppers, which was then quickly extinguished, he said.
Asked if there was any damage to the energy centre, Mr Brosnan said ``not by the fire. It was just us removing bits of the building to find it.''
Crews left the scene by about noon.