Matthew Quigley, 33, was discovered at the bottom of a lift shaft by engineers last week working on a £13m extension to Croydon College.
Quigley, who had been a lift engineer for six years, had been working with Elite Elevators at Croydon College for the past three months.
He is understood to have been carrying out final tests on his own at the time of his death.
Quigley was reported to have suffered two heart attacks while being treated by paramedics before being taken to St George’s Hospital, where he was pronounced dead.
The Health and Safety Executive has launched an investigation into his death, which is being treated as unexplained by the police.
ISG sent staff home as mark of respect.
A spokesman for ISG said: “We are co-operating fully with the appropriate authorities, and until the full circumstances of the incident following the investigation are known, we are unable to make a further public comment.”