"It should be a concern to every business. For small businesses, margins aren't as large so the slightest increase in rent can affect whether they can go back into the CBD and whether they can trade."
She said some landlords had signalled they would work with their tenants to help them return to the city centre.
"But everything is such an unknown. I would love to go back into the CBD."
Matthews said getting businesses back into the CBD would take four or five years.
He said space would have to be used more efficiently. "Previously, there was a ratio of one person per 20sq m, but they will need to start to use less space per person. Rents will go up but the overall costs will remain the same."
He said a lack of demand from smaller businesses that could not afford new rents would eventually drive landlords to break down larger buildings into smaller areas.
Dacombe-Valentine had not been able to get an accurate idea of what the new rents would be. "We won't know until the building is built."
Pete Townsend, of the Canterbury Employers' Chamber of Commerce, said he did not expect all the small businesses that had been in the CBD would return. "Small businesses going back into the city need to remodel so they don't need the same footprint."
He said retail space would cost more a square metre but retailers could get around that by changing their model, so that only a limited amount of stock was on display and customers could browse the rest of the stock online. "Perhaps with a flat screen on the wall. People who change and accept the challenge are doing very well. Yes, it's going to be more expensive but it's a completely different economic environment. Those who understand that will prosper."