Mr Buchanan came under heavy questioning from commission lawyer Marcus Elliott QC for knowing the building was an earthquake risk, but not ordering a more detailed engineering inspection of the building. Mr Buchanan had organised rapid assessments of all his portfolio by Holmes Consulting.
"What do you say to the suggestion that doing no more than an initial inspection... [and] not getting a detailed assessment at all placed all of the tenants of the PGC building at risk of injury or death?'' Mr Elliott asked.
"I don't believe that's correct,'' Mr Buchanan responded.
"I'm happy that what we did was very proactive at the time and I'm very proud of what the team achieved under those circumstances.''
He said initial assessments showed the PGC building appeared to be one of the least damaged buildings.
"If you wanted all the buildings with less than 1 per cent damage to undertake full assessments then you would have pretty much had to close Christchurch for six months. There simply wasn't the engineering resources available to analyse all those buildings.''
Mr Buchanan said he had reassured tenants the building was safe to occupy on the information he had received from Holmes Consulting engineering reports.
"I'm not an engineer. I take advice from professionals. Their role was to make sure the building was safe to occupy.''
Giving evidence at the commission yesterday, Stephen Collins, the building owner, said "trusted'' estate agents and lawyers carrying out due diligence on his behalf had failed to inform him of the reports which showed the building had "the potential for severe failure'' in the event of a major quake.
Mr Collins bought the building from PGC in 2009 and transferred it into his company Cambridge 233 Limited, of which he was sole director.
Yesterday, Stephen Mills QC, counsel assisting the commission, highlighted a 2007 report by Holmes Consulting Group which described the PGC building as having a "severe weakness seismically''.
But Mr Collins said he went ahead with the sale without ever knowing these crucial details.
"This issue was not brought to my attention and there were no discussions of it with me at the time. They were brought to my attention after the earthquake of February 22,'' he said.
PGC company secretary Colin Hair also said yesterday that he had not been told the building was "earthquake prone'' or that it was at risk of "severe weakness seismically.''
"We were not advised of any structural changes that needed to be undertaken.''
Mr Hair also said he had only become aware of this information after February 22.
Also giving evidence today, city council environmental policy and approvals manager Steve McCarthy fielded questions surrounding the green sticker placed on the PGC building on September 5, after a rapid assessment by council staff.
Under cross-examination, Mr Elliott asked Mr McCarthy if the wording on the green sticker "no restrictions to use of occupancy'' sent a different meaning to those which followed beneath it - that the building had only undergone a brief inspection only and that a more comprehensive inspection may reveal safety hazards.
Mr McCarthy confirmed there had been some discussion in council around the wording on the stickers, which had been decided by the Department of Building and Housing.
"Clearly we didn't want to say this building is safe to occupy.''
He accepted that some people may have been assured by the presence of the sign on the building, but said there was a clear message that building owners were responsible for further checks.
"Our expectation was that the building owners and engineers would observe the stickers and get further engineering checks made to the building. If the status of the placard changed we would have expected they would have advised us of that.''