A University of British Columbia undergraduate geography student says Airbnb is having a major impact on Vancouver's rental housing stock.

Iain Marjoribanks just finished a study on Airbnb — with guidance from the B.C. Non-Profit Housing Association — to find out how many people are just renting out an extra bed here and there, and how many are de facto commercial operators.

"What I found in my research was about 77 per cent of Airbnb's revenues come from hosts that don't appear to live in the units they list on Airbnb — what I call commercial hosts as opposed to casual hosts, which is how Airbnb tends to portray itself," Marjoribanks told All Points West host Robyn Burns.

"The top 10 per cent of hosts are these 'mega hosts' who bring in about 27 per cent of Airbnb's revenue and list three or more listings. So those are the people who either take a single house and run it like a hotel with individual rooms, or people who are renting those multiple houses all over town."

Airbnb disagrees

Marjoribanks' conclusions fly in the face of what Airbnb Aaron Zifkin, country manager of Airbnb in Canada, told On The Coast host Stephen Quinn in April.

"The vast majority of Airbnb listings in the world are in people's principal residences," he said. "These are people who are renting out their homes or a room in their homes on an occasional basis."

Marjoribanks says his research suggests only 47 per cent of hosts are principal residences, and if the service was no longer offered in Vancouver, the rental vacancy rate would double from 0.8 to up to two per cent.

Make the company pay?

Victoria is looking to regulate Airbnb in some way, which Marjoribanks says is easier said than done.

He says San Francisco and Portland have had some success regulating the number of days per year a property can be put up for short-term rental and also requires Airbnb hosts to register their rental properties.

"Unfortunately, San Francisco has about a 9.5 per cent compliance rate, and Portland has an 11 per cent compliance rate," he said.

"There's no way for [cities] to go after these hosts, because Airbnb protects the identity of hosts, and therefore, we're unable to figure out who they are, where they are, or how many days they are or aren't renting their units as a short-term rental."

Marjoribanks' proposal is for the cities or the province to fine Airbnb itself for violations, and then presumably Airbnb would pass those fines on to non-compliant hosts.

"If you're going to be taking a full house off the market all year round, you should be paying for the cost that transfers to society," he said.

With files from CBC Radio One's All Points West

To hear the full interview, click the audio labelled: Vancouver Airbnb rentals mostly commercial operations, not extra couches: researcher