They say long-empty office buildings in Civic should be turned into apartments for retirees and young people and small office hubs for entrepreneurial start-ups.

The comments have come from three of the most powerful people to have operated on the ACT planning scene: former Land Development Agency deputy chief executive Dan Stewart, former National Capital Authority chief executive Annabelle Pegrum, and her daughter Elisabeth Judd, a former Housing Industry Association ACT executive director.

The three have created a merged enterprise, Elton Consulting, with Mrs Pegrum saying there was "no excuse for a city like ours to have vacant offices".

"[Canberrans] have had a very good run of commercial returns in office buildings, largely because of the public sector having long-term leases," she said.

"Property owners do have a responsibility to have buildings that meet contemporary demand."

She said incentives would help readapt buildings, many of which had good bones and brilliant outlooks in the upper levels looking back towards Lake Burley Griffin and City Hill.

They would also be wonderful residential locations, she said.

Canberra's office vacancy rate was about 15 per cent, one of the highest in the country.

Mr Stewart said the challenge with higher vacancy rates in the CBD was matching expectations with possibilities.

"Most of the vacancies in Civic are much lower grade accommodation and I think the building owners now are not going to achieve some of the premiums on that lower quality stock when you have much higher quality stock elsewhere around the wider city and CBD," he said.

According to the consultants, space for business incubators was in demand, and a mix of other tenancies, which would more likely take up cheaper space if leasing regulations and designs were changed. They cite Renew Newcastle as a good example to follow, where incubators, artists communities and others have moved into shopping centres on short-term leases.

Mr Stewart said Canberra did not have demand for massive redevelopments across the CBD and parallel alongside other renewal projects and developments mooted for Northbourne Avenue.

Quoting Danish urban visionary Jan Gehl, Mr Stewart said Canberra was having a party in too many rooms.

"We need to focus our energy in an urban renewal sense into one or two areas, and light rail gives an opportunity to focus it in Northbourne Avenue and in the city and step back from some of those other town and group centres," he said.

"There may be opportunities down the track, but we don't need to cannibalise the city projects by having a range of other projects in parallel. For the next three to five years I would love to see the CBD and Northbourne as the cornerstone of the government's urban renewal agenda," he said.

As former principal movers of government planning policy, the three said they had left the public sector for the private sector to recharge Civic.

Carpets have been ripped from floors at their new base, the old Royal Canberra Hospital medical superintendent's residence at Acton, and a live wire hangs from the ceiling on the ground floor.

After the floor is sanded and the wire tucked away in the 1940s home, they will move in, sparking life into the long vacant building and spreading energy across the city.

Using older buildings to accommodate homeless people would be the focus on November 26 of Design Canberra, a forum for architects and other design professionals.

Canberra CBD Limited chief executive Jane Easthope said it was time property owners embraced change and attracted new types of business, but the task would not be easy.

"These buildings are all owned by people so it does depend on what they want to do with them and whether they can be encouraged to embrace change," she said.

"Canberra is full of creative people looking for space, but very few of them are able to spend commercial rates per square metre and this discourages them entering the market."

Ms Easthope said attractive short-term or pop-up leases could regenerate interest in vacant buildings and increase the potential for long-term commercial contracts in coming years.