A thermal imaging camera was used to check for hot spots.
Fire crews had left the scene at 10.40pm last night.
Temporary road closures were put in place on nearby Russell Street, while emergency services worked at the scene.
Former Norwich city councillor Dawn Castle-Green, who lives nearby, said she was sorry to hear the man had died.
She said: I didn t know the man s name, but I would see him when I was walking my dog. I think he d lived there for five or six years. He was always pleasant.
Her husband Ron said the pair had realised something was happening when they noticed blue lights through their window.