"normal operations of a building" that also happen to provide perfectly legitimate answers to the question you posed.

Conveniently, none of these security tapes that should have been recording during a 'power down' have ever surfaced. Missing evidence.... AGAIN .

I wonder where Securacom's on-site offices were.....wtc7 perhaps?

I have a difficult time understanding how anyone could find out that Bouche's brother owned the company in charge of security for THE WTC, UAL and DULLES...the buildings, the airline AND the airport involved in this tragedy...and not come away at least concerned enough to keep digging.