Figure 1
Distribution of households by household size and residential units by number of rooms in existing and new buildings in Germany. Own depiction based on (Destatis, 2022c, 2026a; Statistischen Ämter des Bundes und der Länder, 2022).
Figure 2
Environmental impact of the new construction of one average German SFH; own calculation and depiction based on Mahler et al. (2019) & Zimmermann et al. (2023).
Figure 3
Municipal development and infrastructure costs per residential unit for SFHs and MFH apartments. Own representation based on cost data from the Federal Foundation for Building Culture (Bundesstiftung Baukultur, 2020), converted using the construction price index (BKI, 2026) to Q4/2025.
Table 1
Forms of change in the living situation of SFH residents (Zimmermann et al., 2025a, p. 28, own translation).
| MOVING TO AN MFH | CONVERSION AND RENTING OUT SEPARATE APARTMENT | SHARED LIVING THROUGH PARTIAL RENTAL OF ROOMS | |
|---|---|---|---|
| Description | Current household moves to a smaller apartment in an MFH | Rebuilding of the SFH to create two separate residential units (e.g., a granny apartment) | Renting out individual rooms within the SFH that have not previously been used for living; part of the living space (e.g., kitchen) is shared |
| Impact on the housing market | Increasing availability of SFHs for sale or rent, allowing a family or shared living community to move in | Increasing availability of (small) apartments within the SFH | Increasing availability of single or several rooms within a shared SFH |
| Dealing with existing SFH |
| Remaining in the possession of the previous owners | Remaining in the possession of the previous owners |
| Necessary structural changes | None (if necessary, by new owners/inhabitants) |
| Minimal to none |
| Type of living space created | Entire SFH | Individual apartment in a single-family home | Individual rooms (shared apartment) |
| Time frame for implementation |
| Medium term | Short term |
| Legal form of new living situation (in SFH or MFH) |
|
| Rental |
Figure 4
Willingness to change the living situation of SFH residents over the age of 50 in 1–2 person households in districts with a vacancy rate below 6% (Bader et al., 2026; Gabriel et al., in publication).
Table 2
Housing potential of households in SFHs with one or two persons in regions with low vacancy rates (Destatis, 2022b, 2022c; Gabriel et al., in publication).
| POTENTIAL | EXTRAPOLATION OF THE SHARE OF RESPONDENTS WHO CAN IMAGINE … | MILLION HOUSEHOLDS (TOTAL = 8.7 m) | |
|---|---|---|---|
| YES | YES + MAYBE | ||
| Any form of change | … at least one form for change. | 2.5 m | 4.0 m |
| Moving to an MFH | … moving out of their SFH into an MFH. | 1.6 m | 2.7 m |
| Conversion of a SFH and renting out | … converting/splitting their SFH and renting out a new separate apartment. | 1.0 m | 1.9 m |
| Shared living in the SFH | … renting out individual rooms in their SFH. | 0.7 m | 1.3 m |
Figure 5
Results GHG calculations per SFH household changing its living situation; own calculation and depiction based on Mahler et al. (2019) & DGNB (2025).