Real estate owners and developers have not rushed to convert office buildings into housing because many are fundamentally unsuited – they are land-locked or have large floorplates resulting in areas deprived of natural light required for residential use. Could uses be found for these “dark spaces” that would allow more buildings to be candidates for conversion from office to residential use?

Architect Charles Bloszies FAIA has pondered this question, and his firm has come up with some novel ideas for filling dark spaces with viable uses. All tall buildings have (and need) dark spaces for core components like elevators, stairs, and utility shafts. In fact, an office conversion actually adds more dark space because office buildings contain more elevators than similarly sized apartment buildings.

Over the last year, Bloszies’s architecture and engineering firm has evaluated costs and timeframes for specific buildings as well as for typical conversion projects, which offer some revealing takeaways. One analysis addresses the “dark space” issue, which offers ideas for dark space uses in areas not suitable for residential uses or not required for the building core.

Dark Space
"At first glance, many high-rise office buildings may seem unsuitable for conversion to residential use. This is because the depths of their floorplates would preclude sufficient natural light from reaching housing units in the center of the building,” says Bloszies. "However, upon further analysis it becomes evident that the darker cores of high-rise office buildings can be adapted to host dark uses – commercial and other uses that do not require natural light." 

The graphics attached show evaluations for iconic San Francisco office structures, revealing the amount of dark space can range from 12% to 19% of the available floor area. “In contrast to cutting in light wells and thereby reducing floor area, the dark spaces can be repurposed as income generating real estate,” adds Bloszies. These uses include:

• Autonomous Vehicle Fleet Bases
• Vertical Farming in Unused Elevator Shafts
• Self/Public Storage
• Server Farms

Dark space could be consumed by live-work type units with work-at-home offices occupying deeper floorplans. On lower floors where access to perimeter light may not be available, dark space uses could include gyms, music studios, nightclubs, movie theaters, black-box performance and cultural spaces, broadcast facilities, or even fulfillment centers.

Bloszies believes “office conversions must engage the city at the street level to be a contributor to the urban fabric, and again, dark uses can fill the need.” 

New Regulations
In addition, new policies enacted by San Francisco’s city planning department have the potential to ease office-to-residential economics. These include the brand-new "Commercial to Residential Adaptive Reuse Program" as well as updated policies for:

• Permitting for live-work arrangements.
• Eliminating restrictive unit mix requirements.
• Placing older buildings under consideration for conversion eligibility.