The kitchen of one of Stay Alfred's short-term rentals in downtown Denver. 

(Courtesy Stay Alfred)

As Denver's City Council works on new rules for Airbnb and other short-term rental services, regulators are facing a vexing question: how to enforce regulations once they are enacted.

Other cities, including San Francisco, have passed strict rules on how often a unit can be rented. But they are having trouble enforcing them. Airbnb and its peers don't share internal data with regulators, so officials don't know who to go after.

“Unless we go knocking on every single person’s door, it’s hard to be proactive about this,” said Denver City Councilwoman Mary Beth Susman, who's been working on the new rules for more than a year.

A ballot measure in San Francisco that would have, among other things, required Airbnb to share its data with the city, failed by a wide margin this week. The company says it's the hosts' responsibility to make sure they aren't breaking local laws.

Denver is looking at a different strategy. Short-term rental rules under consideration in a council committee would ban hosts from renting a property that isn't their primary residence. The draft rules would also require hosts to obtain a business license from the city and pay the same taxes hotels pay.

Susman also wants platforms like Airbnb to include license information on each listing in Denver. If the license is missing, regulators can then follow up with the host. "It will help us with the enforcement," she said. Whether Airbnb and others will play along is an open question, however.

Susman's efforts have been hampered by a lack of information. But the councilwoman said a data-heavy CPR News report published earlier this week has helped illuminate the extent of short-term rental usage in the city. We scraped Airbnb.com and found nearly 1,700 listings in Denver. We estimated that 118 of those are busy enough that they probably are full-time vacation rentals. A housing expert at the University of Denver said that's not enough to affect rental prices in the area. 

Still, not all are convinced the problem has been overstated. Margie Valdez, chair of the Inter Neighborhood Cooperation's zoning and planning committee, said our reporting didn't sway her. 

“Any impact is significant," said Valdez, who's been involved in the City Council discussions for months. “I don’t want to come across as opposing, totally, short-term rentals. I just think we have to do it the right way."

Valdez is worried investors who buy up apartments and homes and rent them out on Airbnb. Our data shows 54 Airbnb hosts in Denver have three or more listings, suggesting they are professional landlords and not someone renting out their home only occasionally. 

But data what the data proves and what it suggests are two different things. The Airbnb host with the most listings in Denver -- "Jordan" -- is actually a legally licensed luxury hotelier called Stay Alfred. It uses the platform to facilitate rentals. 

“These aren’t affordable homes we are taking off the market," Stay Alfred's marketing director Skyler Reep told Colorado Matters host Ryan Warner. 

The company doesn't own its properties, either. It picks up leases on empty units from building owners and then rents them out on a short-term basis. So some of these "super hosts" like Stay Alfred already play by the rules.

The primary residence requirement will likely be the most controversial. The Denver Short Term Rental Alliance, a group of hosts who use Airbnb and other platforms, say it violates their property rights and unfairly makes them a scapegoat for the city's housing woes. 

Susman expects the debate to heat up as the draft rules are finalized and move to the full Council, which is expected early next year. And Airbnb, fresh off its victory in San Francisco, is mobilizing its huge user base to engage in public policy debates across the country. Expect to see that here, too.​

CPR News' Kareem Maddox contributed to this report.