A fault which caused Statistics House to partially collapse was identified more than three years before the November earthquake.

On Friday a government inquiry into the performance of the five-storey office building was released, with the Government promising changes to building and design standards.

Although a number of Wellington buildings were damaged in the November quake, most attention focused on Statistics House when it emerged that two floors in the building - including areas often accessed by the public - had partially collapsed.

ROSS GIBLIN/FAIRFAX NZ While a number of buildings were damaged in the November earthquake, the partial collapse of Statistics House quickly led to a government inquiry.

Building and Construction Minister Nick Smith acknowledged on Friday that the performance of Statistics House, completed in 2005, "was unacceptable and could have caused fatalities".

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The report concluded that Statistics House "generally" complied with the building standards of the time it was built. However elements of its design, coupled with the unusual characteristics of the quake, caused the building to fail.

Statistics NZ. A large concrete beam in the ground floor of Statistics House collapsed in the quake.

Such were the forces faced by the building, concrete beams in the floors stretched, leading parts of the floor to collapse.

But the report also revealed the design issue which led to the failure of the building was identified in 2013 in a report conducted in the wake of both the Seddon earthquake and the Canterbury Earthquake Royal Commission.

"The seating of floor units at the four corners of the building were identified as a critical element," the report said.

Ross Giblin/FAIRFAX NZ The entrance to Statistics House.

Work was underway to fix the problem on the upper floors of the building, and where it had been completed or partially completed, the building performed as it should have.

Where the work was not completed, the building partially collapsed.

CentrePort, which owns Statistics House, has refused to comment beyond a statement that the 2013 report found the building was up to 90 per cent of the current building code.

Labour's Grant Robertson, the MP for Wellington Central, said the work to rectify the problems identified in the building should have been completed by the time of the November quake.

"CentrePort have to front up and explain why that wasn't done," Robertson said.

"If the quake had happened just after midday, instead of just after midnight, people would have died. It doesn't get any more serious than that."

Statistics New Zealand chief executive Liz MacPherson confirmed that she was not aware of the substance of the 2013 report into the building, only learning of the issue as part of the recent inquiry.

While the Government Property Group was told of the issue as part of negotiations to extend the lease of Statistics House, MacPherson said as head of the lead tenant of the building, she had responsibility for the health and safety of all tenants.

As such, she believed she should have been told. If she were told, she would have taken advice about whether to stay in the building.

MacPherson said she hoped the report would hasten a decision about the future of Statistics House.

"I've given my staff assurances that I'm not taking them anywhere that I can't assure them of their safety, both physically, and I'm also concerned about the emotional safety of staff."

The Public Services Association (PSA), a union for public servants, called the report "deeply concerning" and showed a lack of communication.

"Hundreds of our members would have come to work each day unaware of the risks they faced while the building's issues remained unresolved, and this is unacceptable," PSA national secretary Erin Polaczuk said.

Smith defended CentrePort's decision, saying the company had been responsible in commissioning engineering reports, which recommended the work to repair the issues be completed within five to 10 years.

"The reality of the risks of earthquakes is that we will never have 100 per cent safety. It's about taking a prudent and sensible view."