"The suburban office market has suffered in the last five years, losing tenants to the city and vacancies increasing.
"Out in the suburbs we've got vacancies up to 16.4 per cent at the moment and rents in the suburban areas have drifted backwards and stagnated, whereas in the [central business district] we are finally getting some rental growth because there's competition for space," he said.
Sellars said there was currently no corporate office space larger than 350 square metres in the central city's inner core, the area that covered the retail precinct through to Cathedral Square.
He did not believe a commercial building boom was on the horizon, but felt more buildings were needed.
"It's more likely to be a considered redevelopment process and I'd be surprised if we see any more than three or four, or maybe five at the maximum office buildings built in the next five to six years."
It wasn't just office vacancies diminishing, retail vacancies also reduced year-on-year, according to Colliers data.
In 2018, nearly a quarter of retail space in the central city was vacant, and it was now at 6.1 per cent, Sellars said.
- RNZ