Many European cities suffer from a misallocation of space: an oversupply of office real estate and a lack of affordable housing. Vacant offices carry high potential to provide centrally located and low-carbon housing. This report explores how repurposing offices can provide a practical, and often faster, solution to affordable housing. While office conversions are already widely carried out, there has been no clear understanding about common challenges faced and regulatory changes needed across Europe.  

The report presents an analysis of five cases (four completed and one ongoing conversion)  in five countries across the EU, identifies the key success factors that have enabled such projects and which could inform replication, and assesses their ecological, economic, and social impacts and benefits. 

Key findings 

• Repurposing existing structures does not necessarily mean compromising living standards or quality of execution. On the contrary, conversion projects provide opportunities to combine energy efficiency renovation, innovative solutions and forward-looking design principles. 

• Conversions provide an opportunity to create more needs-based residential units. This means that apartment sizes, building functions and features are adjusted and tailored to the demographics and social needs of tenants.  

• Every conversion project is unique, making it impossible to generalise whether conversions are consistently cheaper or more expensive than new construction. What is clear, however, is that they involve greater risks and uncertainties than building new, due to potential hidden structural defects or the presence of hazardous materials which can lead to unforeseen issues once work begins on site.  

• The four completed cases explored in this study, however, have all achieved lower costs than equivalent new-build projects. This demonstrates that, under the right conditions, conversion can be both technically feasible and financially viable.  

• Cooperation and support from local actors, including both the public sector and private developers, is a key factor for success. A favourable acquisition price (particularly for publicly-owned buildings), along with financial support and fast-track approval processes, are essential for successful and high-quality implementation. 

• Streamlined permitting and mixed-use zoning are important success factors. In contrast, compliance with overly detailed building regulations requires complex adjustments which drive up costs. 

• Public procurement that prioritises the reuse of existing buildings acts as an important lever for shifting mindsets from new construction to conversion. 

• Unlocking affordable homes through office-to-housing conversion in cities can avoid carbon emissions not only from new construction but also from the needed infrastructure (e.g. roads, utilities) and commuting typically associated with suburban development. High energy performance is also achievable in office-to-affordable housing conversions.