LONDON. The hollowed-out office blocks that punctuate city skylines from San Francisco to Sydney have become a defining emblem of the post-pandemic economy. As vacancy rates in central business districts reach historic highs, municipal authorities and property developers are being forced to confront a fundamental question: what to do with millions of square metres of empty commercial space?

The structural shift towards remote and hybrid work, accelerated by lockdowns, has left a glut of Grade A office towers with occupancy rates below 50%. In the United States, the national office vacancy rate hit 19.6% in the second quarter of 2024, according to Moody’s Analytics. In the City of London, vacancy stands at 11.5%, its highest since the early 1990s recession.

The response has been a wave of conversion projects that attempt to repurpose these assets for residential, educational, and cultural use. The logic is compelling: urban centres need footfall to sustain retail, hospitality, and public transport. Empty offices drain value, blight neighbourhoods, and reduce tax revenues.

In New York, Mayor Eric Adams’s “City of Yes” zoning changes, approved in December 2023, have made it easier to convert older office buildings into apartments. The policy waives certain density restrictions and reduces parking requirements. Developers have since filed plans to create 20,000 new homes in buildings such as the former Pfizer headquarters and the Art Deco tower at 1 Wall Street.

London is pursuing a more piecemeal approach. The City Corporation has granted planning permission for the conversion of 10 Fenchurch Avenue into a 1,000-student campus for the London School of Economics. Nearby, the owner of the “Walkie Talkie” tower has proposed turning eight floors into a “vertical village” with co-working spaces, a gym, and a cinema.

But the economics are difficult. Office-to-residential conversion in the UK typically costs between £300 and £500 per square foot, according to Knight Frank. The structural constraints of office towers – deep floor plates, core toilets, limited natural light – often require extensive demolition and rebuilding. Only about 10% of existing offices in London are considered feasible for residential conversion.

Other cities are experimenting with interim uses. In Tokyo, the government offers subsidies for temporary conversions of unused floors into childcare centres or art galleries. In Paris, the city council has acquired a vacant tower in La Défense to house a university and a public health clinic.

The long-term implications are significant. A permanent reduction in office demand could reshape tax bases, transit networks, and urban planning models. Central business districts that rely on commuters may need to become more mixed-use to survive. The mayor of Sydney, Clover Moore, has argued that “the future of our city centres lies in 24-hour communities, not just 9-to-5 workplaces.”

Yet critics warn that haphazard conversions risk creating substandard housing or sterilising valuable commercial land. The British Property Federation has called for a more strategic approach, including a national task force to assess the best uses for each building.

For now, the repurposing of empty offices remains an experiment. The outcome will determine not only the fate of billions of pounds in real estate assets but the character of cities themselves.