In the Paris region, over 5.6 million square meters of office space sit vacant. At the same time, demand for housing (especially social housing) has reached critical levels, with fourteen applications per allocation on average. This mismatch – between empty offices and overcrowded homes, raises important issues about how we can make better use of the built environment to meet urgent housing needs.
The post-pandemic city
The rise in remote work post-pandemic, company relocations and shifting lifestyles have left many commercial buildings obsolete. Office vacancy rates surged across major cities, and land developers have paused new projects, deterred by soaring land prices and shifting demand.
Converting offices into housing is an appealing and pragmatic option, and a French law to facilitate offices-to-homes conversions received unanimous support in the National Assembly and was adopted last June. But can it work?
Not a new idea – but a new urgency
Switching offices for homes was an idea pushed in another OECD Cogito article four years ago (“Can office conversion help solve the housing crisis in cities?”). And indeed, in older European cities, the conversion of buildings to new uses has always been part of the policy toolkit. Former factories became lofts, convents became schools, and post offices turned into housing long before the pandemic arrived.
Doing so makes sense. Reusing existing buildings can emit up to 50% less embodied carbon than demolition and reconstruction while addressing housing shortages.Conversions should ideally go hand in hand with energy-efficient upgrades (insulation, efficient heating/cooling, ventilation), a strategy which would result in lower total emissions over a 25 year period.
In Frankfurt, Germany, high office-vacancy rates in the neighbourhood of Niederrad, originally conceived as an office district, motivated a large-scale conversion project at the end of the 2000s.
Between 2007-15, about 3 000 apartments were completed and the office district became a lively, mixed-use neighbourhood equipped with new amenities and infrastructure, such as child day-care facilities, parks, and bicycle lanes.
Learning from Britain: A step too far?
Yet other countries have had more mixed results. In the United Kingdom, a similar mix of housing shortages and vacant commercial properties in certain areas prompted legislation allowing Permitted Development Rights (PDR): office-to-home conversions without traditional planning approvals.
This regulatory free pass enabled the creation of more than 24 000 affordable homes in a decade. However, there has been a backlash in some areas. In Croydon, a south London business district, many conversions were flagged for poor quality and safety issues. One office block was converted into flats despite lacking proper fire safety infrastructure. Another project delivered nearly 600 flats – many with no outdoor space or natural light.
A study by University College London (UCL) found that overall, only 22.1% of PDR met national space standards, compared to 73.4% of those created through full planning permission, not to mention standards for ventilation, natural light or habitability. While fast, this model raises serious questions about quality, liveability, and long-term inclusion, especially in already fragile neighborhoods.
France’s cautious but committed approach
France is taking a more measured path. Rather than removing regulations, it is adapting them. The 2025 law aims to scale up conversions by relaxing certain technical standards (under supervision), granting targeted exemptions from planning rules and streamlining slow administrative procedures.
The goal is to make conversions faster without compromising on quality or sustainability. Several projects have already set the tone. In Pantin, a former office building was transformed into 70 residential units by Croix Marie Bourdon architects. In Brest, a post office became a retirement home, preserving Art Deco features while upgrading for modern needs. And in Paris, the Reuilly barracks and Îlot Saint-Germain showcase how public-sector leadership and design competitions can deliver high-quality, large-scale social housing.
These projects combined architectural simplicity with comfort – but also revealed the cost and complexity of adapting office space to residential uses. Excessive floor depth, low ceiling heights, and ventilation and natural lighting constraints make many buildings difficult to adapt without major renovation work. Deep conversions often involve significant investments such as reworking floor layouts, installing new ventilation or insulation, possibly removing hazardous materials, upgrading building services, which in many cases can make conversion per square meter as expensive as new construction.
Recent French data show that conversions typically cost from €2 050 to €4 500 per m² of habitable floor area, slightly above the €2 000 – €2 200 per m² typical for new social housing in Île-de-France. However, in dense urban areas like Paris, where land prices are high and building land rare, conversions can still be financially competitive once the cost and time savings from avoiding demolition, displacement and lengthy planning permit processes are considered.
Source: https://www.croixmariebourdon.fr/?work=transformation-de-bureaux-en-70-logements-pantin & https://www.chatillonarchitectes.com/portfolio/anciennepostedebrest/
What about other countries?
Beyond France and the UK, other OECD countries are adopting similar approaches. In the Netherlands, simplified planning rules supported conversions in Amsterdam’s Zuidas district. In Canada, the federal government’s Housing Accelerator Fund includes provisions to support downtown office-to-residential conversions. In Japan, flexible zoning in Tokyo allows obsolete office buildings to be partially converted into co-living or senior housing.
These examples show that success not just on deregulation but on streamlined systems that integrate housing, planning, and climate objectives.
What next?
France’s new legal framework is a step forward, and other countries are watching closely. The key will be to act quickly, but without cutting corners, and to remember that the right to housing should never come at the expense of dignity.
Read more from the OECD’s report Cities Turning crisis into change Post-pandemic pathways to resilience in complex times. Check out a related Cogito article Can office conversion help solve the housing crisis in cities?.
Marie Cardwell de Bryas is an architect working between Paris and London, where she serves as co-director of the French office of Stephen Taylor Architects. Her practice has focused primarily on delivering high quality contemporary buildings and urban projects with a strong social and cultural focus, including public sector projects such as the delivery of housing schemes for several London boroughs. Marie holds a Master of Architecture from the University of Edinburgh and a BSc in Architecture from the University of Bath and is a registered architect both in France and the UK.