"Many others were injured - some very seriously. Although they live on, their lives were profoundly affected by their injuries and we acknowledge their ongoing suffering.''
Justice Cooper said the hearing's goal was to "advance the understanding'' of why the building collapsed and he apologised to grieving families for what may appear to be "a clinical exercise''.
But he added: "I want to assure you that we did not embark on the process without an appreciation of the emotional toll of these events have had on those directly affected.
Many of you are here today and we welcome you to this hearing.''
Stephen Mills QC, counsel assisting the commission, outlined the terms of reference for the hearing, which is expected to last at least five days and spill over into next week.
Mr Mills said the "first and obvious'' question that the hearing will address, is why the PGC building "failed so severely'' and why it caused "extensive injury and death.''
It will also investigate the "nature and effectiveness'' of the assessments after the September 4 event.
Mr Mills said the hearing will hear evidence from experts who concluded the building collapsed after the failure of the "central core tower'' during the magnitude 6.3 shaking and its resulting large lateral displacement.
He said the building was damaged on September 4 and was assessed the following day by Christchurch City Council officials who deemed it Level 1, and meant it was "green stickered.''
The owner of the building, Stephen Collins of Cambridge 233, instructed real estate firm Harcourts to inspect the building, and they commissioned Holmes Consulting Group to carry out the required work.
The initial earthquake inspection on September 7 by chartered professional engineer Mark Whiteside confirmed the green sticker status and reported: "Building OK to occupy (structurally).''
A second Holmes report on September 16 retained the building's green status, but added: "More cracks observed, minor in sheer walls.''
A third assessment on October 15 again concluded that it was "OK to occupy.''
However, Mr Mills said that after another aftershock - possibly after the Boxing Day 4.9-magnitude quake - tenants discovered cracks which "caused concern and led them to press for another report.''
On January 27, a fourth Holmes' report concluded it was safe to occupy, but did confirm the cracks which tenants had raised concerns about.
Mr Mills said: "Throughout this period - September to the end of January - Harcourts was issuing monthly reports to the owner which included a section on earthquake updates, and it said each month to the effect it was 'safe to occupy'. It was consistently structurally safe to occupy.
"That reassurance from engineers assessments was repeatedly conveyed to the tenants and staff.''
However, engineering company Becca conducted a report on the behalf of the Department of Building and Housing which backed Holmes' initial assessments and said the cracks had not contributed to the building's collapse.
The hearing this morning also heard evidence from an eyewitness to the building's destruction.
Christchurch electrical engineer Robert Wynn was working at his desk on the fourth floor of the 76-metre-high Price Waterhouse Cooper building on Armagh Street when the February 22 earthquake struck at 12.51pm.
He told the hearing how he looked out of the window as the shake grew in intensity.
Mr Wynn said: "Cars started wobbling around. Out of the corner of my eye, I saw the PGC building collapse.
"My view was partially obscured by trees. But I could see the top two floors and I could see it drop.
"It was very catastrophic. It flattened itself as it went down, and tilted and rotated as it fell.
"The collapse was very quick - like a controlled demolition you would see on TV.''
The witness estimated that the building collapsed "five to eight seconds after the shaking started'', after it had peaked at its "most intense'' point.
The hearing continues.
