Renamed Les Grands Voisins, or The Great Neighbours, the site is a magnet for Parisians and tourists alike, its former treatment rooms, A&E building and wards now a hub of social and commercial enterprise. Alongside a hostel providing 600 beds for the homeless are artisan studios, pop-up shops and startups.

It’s like a village, an inclusive space with social areas and job opportunities where different people can interact,” says William Dufourcq, director of Aurore, the charity that runs the homeless shelter. “We were overwhelmed with its success.”

Closed since 2011, the hospital is slated for redevelopment into a new neighbourhood with eco credentials, private and social housing, shops, commercial and public facilities and green space.

Planning, clearance and construction on such a large scale takes time and, rather than leave the 3.4-hectare site empty for years, the developer, Paris Batignolles Aménagement, opened it to local organisations rent-free. The lease was scheduled to end this year, but has been extended until mid-2020 while construction begins on other parts of the site.

Les Grands Voisins is an example of a “meanwhile space”: a disused site temporarily leased or loaned by developers or the public sector to local community groups, arts organisations, start-ups and charities. Calls for making use of such spaces in other crowded urban centres are getting louder. A report published in October by the thinktank Centre for London highlights both the need for and positive possibilities of utilising empty urban sites and how this could transform the landscape of cities around the globe.

“The aim was to show the value ‘meanwhile use’ can add in cities where there is pressure on space,” says Nicolas Bosetti, one of the report researchers. He says public and private operators in Paris are more ambitious than those in London in exploring the use of disused buildings from metro stations to former nightclubs for short-term use as charity and cultural venues.

Other meanwhile spaces in Paris include Exelmans, a former police residence repurposed as a shelter for the homeless and refugees, run by Aurore on a two-year lease, and the Parmentier electricity substation, where the art collective La Générale has operated since 2008.

The substation, which is soon to be redeveloped, was included in Paris Reinvented, an initiative from the mayor’s office currently in its second year. Disused public sites are put up for auction to developers and architects who compete with plans for their redevelopment. “Les Grands Voisins showed how something like this can change an area and help plan future urban projects,” says Marion Waller, adviser to Paris’s deputy mayor for urban planning. “We didn’t want to sell buildings to the highest bidder but to the most innovative solution.”

The idea of loaning empty urban spaces to worthwhile causes is gaining ground elsewhere, with thriving projects in the Danish city of Aarhus and Philadelphia in the US, where it’s called “temporary urbanism”. However, in space-squeezed London, urban sites can remain empty for years, mainly because they have no obvious commercial potential or are waiting for permission to be developed.

The Centre for London found that an estimated 24,400 commercial properties in London are currently empty, with around half having been unused for more than two years. The total available vacant space, 6.5m sq metres, is equivalent to 27 times the footprint of Westfield London, Europe’s largest shopping centre. The majority of such places are owned by local authorities and developers. “Only one of 33 London borough councils publishes a database of vacant property and only one council keeps a list of groups interested in vacant spaces,” says Bosetti.

Bosetti thinks property owners could do more to match available sites with needy groups but says local authorities are afraid of squatters or allowing in destructive elements. “One of the main barriers to meanwhile use is the perception that hoarding a site is safer,” he says. “Often the opposite is true. Opening a site to a community and encouraging interaction with residents usually sees a reduction in antisocial activity.”

Squatting and vandalism are more likely if a building remains empty for too long, so one benefit of temporary tenants is the reduction in security costs. Another, according to Simon Hesketh, director of regeneration with the British developer U+I, is the connection a meanwhile space can forge with the community prior to redevelopment.