Can Sufficiency Approaches Solve the Housing Crisis and Save the Climate?

There is a lack of affordable housing in Germany and France. Two key factors in this crisis are the uneven distribution of living space and the continuing upward trend in the per capita consumption of living space. This not only exacerbates the housing crisis, but also cancels out energy savings achieved through building renovations. We need creative solutions to make better use of the housing stock. Our new RIFS Discussion Paper takes a look at approaches in both countries.

Creative local solutions

In 2021, the city of Brest in north-western France suddenly surged in popularity among students. The university residence halls were unable to accommodate the sharp rise in the number of young people who wanted to move to the harbour city. In response, the city launched a campaign to encourage homeowners to rent spare rooms to students. This creative solution was not only cost-effective and space-saving, it also helped to strengthen communities and foster social cohesion. So-called “empty nesters” – older people whose own children have left home – often have spare rooms in their homes that they could (sub)let to young people. 

Obviously, it will take more than a PR campaign to solve the housing crisis. However, the example invites us to rethink our approach to housing issues. At the Franco-German Forum for the Future, we set out to learn more about creative local solutions like this and present them in a RIFS Discussion Paper. There is enormous potential in the existing housing stock to create new living space through subletting, restructuring, and home swapping. Housing economist Daniel Fuhrhop has written about the phenomenon of "invisible living space" and estimates that the equivalent of 100,000 new flats could be unlocked every year. Unlocking existing residential space also contributes to efforts to protect the climate and environment through energy and resource savings and by slowing the sealing of urban soils.

Sufficiency approaches have many advantages

Local government entities in particular can play an important part in promoting what is known as “housing sufficiency” – gains in energy and space savings achieved through social innovations. Interestingly, our research showed that local authorities in France and Germany are not significantly motivated by environmental concerns. Rather, unlocking existing residential space promises to deliver a range of benefits. Take Hiddenhausen in North Rhine-Westphalia (Germany), for example, where local authorities launched a grant programme called "Young buys old", which offers grants to young people for the appraisal, purchase and renovation of old buildings. The programme attracted young people to the town, helping to revitalise its inner precinct and limiting urban sprawl. 
 

Downsizing or subletting can also have advantages for individuals: Lower energy costs, less or shared maintenance and improved accessibility to community spaces. Surveys show that around a fifth of the population in Germany and France would be prepared to downsize (Gaspard 2024; WWF Germany 2024). The proportion is even higher among 60- to 69-year-olds. A lack of alternatives is currently preventing many people from freeing up living space for those who urgently need it. It is the availability of suitable housing for home swapping that decides whether people experience downsizing as a loss or a gain in personal freedom and quality of life.

A political rethink is needed

The housing crisis is a complex problem and there is no silver bullet. Efforts to ramp up the construction of new builds in Germany and France have done little to reduce inequalities in the distribution of living space – at the expense of huge areas of land lost to development and the consumption of enormous amounts of resources. The local sufficiency approaches that we analysed have had only limited impact to date. One reason for this is that the major trends in the rental and property market are pushing in the opposite direction. Downsizing is often not a financially attractive option. On the other hand, we are also culturally accustomed to seeing large living spaces and owner-occupied homes as status symbols or are emotionally attached to them. 
Looking at the many advantages of sufficiency can help to change our perspective. Demographic trends and our ageing society mean that we really need to rethink our approaches to housing and community-building. We hope that these examples from Germany and France might inspire people to consider subletting or to find out more about converting their building or apartment. 
 

Read the full RIFS Discussion Paper on housing sufficiency: 

• Spinrath, T. E., & Davenas, M. (2025). Wohnsuffizienz: das vergessene Potenzial der Energiewende? Thesen aus dem deutsch-französischen Dialog. RIFS Discussion Paper, February 2025. 

Find out more about the Franco-German Forum for the Future and our recommendations for action at:  https://df-zukunftswerk.eu.