In Boulder, where open space is a rare commodity, some developers are converting commercial spaces into housing as a way to expand housing stock in the city.

A new project at 3300 Penrose Place, located in an office park near the Diagonal Highway between 30th Street and Foothills Parkway, seeks to transform a portion of an office building into permanently affordable housing and add several more residential buildings on the site.

The site has served as the headquarters of the Geological Society of America, a society of scientists from academia, government and the private sector, for decades. The original building was built in 1971, and an addition on the west end of the building was completed in 1990.

Ian Swallow, senior development project manager for Boulder Housing Partners, said that during the COVID-19 pandemic, as more employees started to work from home, the Geological Society found it was not fully utilizing the space in the building, and the group expressed interest in giving the building a new purpose.

“For them, I think (they appreciated the) opportunity to repurpose an asset they have. And also, I think they were excited about a cause like affordable housing and the ability for the property to be used for that,” Swallow said.

Boulder Housing Partners bought the building in April 2022 for $10.3 million and has been leasing it back to the Geological Society since then, according to Swallow.

The original, 53-year-old portion of the Geological Society building will be one of several residential buildings in the finished complex, which will add 113 new permanently affordable housing units to the city’s supply. Boulder Housing Partners is also pursuing historic landmark status for the original part of the building, which exemplifies Brutalist architectural design.

Permanently affordable housing units are deed-restricted so they stay affordable in perpetuity for people making no more than a certain percentage of the area median income, or AMI. Swallow said the specific AMI cutoffs for the complex haven’t been set yet.

In addition to the housing units, there will be an on-site leasing office and a daycare center with a play area that will serve about 20 children. Boulder Housing Partners used its own funds to buy the land, but the housing will be funded in part by the Low Income Housing Tax Credit. Swallow said he also anticipates funding from Boulder, the county, the state and other sources.

Although 3303 Penrose Place is a relatively large housing project for Boulder, it is similar in size to several other housing developments that have sprung up recently. A comparable example is the Rally Flats development, which is repurposing the old RallySport Fitness Center building near 29th and Bluff streets and turning it into a 100-unit affordable housing project. That project broke ground last fall.

Swallow said turning a commercial building into a residential space presents some added logistical challenges, but it may become more common in the years ahead, especially in Boulder, where there’s little room for the city to expand outward. He said the housing authority is excited about the idea of taking underutilized spaces and turning them into housing in desirable areas to live.

“We’re not expanding out. So this is a way to do really good infill development in areas that already have really good access to services, which is what we see with this site,” he said.

The site is located close to Wonderland Creek, the Diagonal Plaza Shopping Center and several transit routes, including the BOLT and the BOUND buses. The zoning on the site also already allows high-density residential uses.

Swallow said the housing authority will need to secure funding and permits for the project, but he expects construction could begin as soon as 2026.