The window failure that sent shards of glass plunging from the 17th floor of a high-rise in San Francisco’s Financial District is being attributed to heat fluctuations, according to a violation notice issued by the city’s building inspection department. No one was injured when pieces of glass fell from the Front Street side of the 24-story high-rise at 150 California Street. The window that broke had been heat treated, according to the violation notice, and was protected by a laminated coating intended to keep glass from breaking apart should the window get hit by something or crack suddenly.   The city inspector who issued the notice of violation, Matthew Sum, wrote in the narrative that he observed the glass break free and fall onto a sixth-floor rooftop patio. In the notice, Sum quoted the building engineer at 150 California as saying the window failed “due to thermos change.”   Building officials late Thursday clarified the notice language should read, “thermal change.”  While experts say it is rare, heat treated, laminated windows have been known to fail when heat builds up in the space between panes, and that pocket of air expands. A photo taken Wednesday shows extensive cracking in a third-floor window of the high-rise as well, that one glass expert we spoke to says is consistent with a thermal-related failure of a laminated glass pane.  The building management did not respond to requests for comment for this story. Earlier, officials had said they were cooperating with authorities in the aftermath of the incident. ...read more read less