Transforming Invisible Buildings

Buildings account for around 36% of carbon dioxide emissions and 40% of energy consumption in the European Union. At the same time, millions of homes remain vacant or underused, while new construction continues to consume land, materials and energy. Reactivating existing buildings offers a major opportunity to reduce emissions, especially embodied carbon, which can be up to 85% lower than in new construction.

The project is being implemented in Greece, Croatia, and Slovenia. In the capital cities of Athens, Zagreb, and Ljubljana, many homes remain vacant. At the same time, national strategies are increasingly focusing on energy efficiency, renovation, and urban renewal. However, vacant housing has so far received little attention in these efforts. This is where the project comes in: it links the reactivation of vacant buildings with modern energy efficiency measures. In doing so, it supports climate-friendly urban development, reduces emissions, and helps address the shortage of affordable housing.

The project reduces emissions from the building sector by reactivating vacant and underutilised buildings instead of constructing new ones. It integrates vacancy reactivation into existing One-Stop-Shop¹ services in Zagreb, Ljubljana and Athens, connecting housing, energy efficiency and urban policy.

The project maps vacant buildings, identifies reactivation potential and supports municipalities through policy labs², workshops and capacity-building activities. These formats allow local authorities, property owners and civil society to test policy instruments and practical solutions for bringing empty buildings back into use. Feasibility and activation measures focus on improving energy performance while making buildings liveable and affordable.

A replication programme supports six additional cities in implementing small-scale vacancy reactivation actions, enabling peer learning and transfer of tested approaches. Through advocacy, stakeholder dialogue and high-level engagement, including mayor-level exchanges, the project embeds vacancy reactivation into long-term urban and climate policies and supports replication across Europe.

¹ Central contact points where property owners or municipalities can access all relevant information and services in one place—for example funding schemes, advisory services, permits, and technical support. The aim is to reduce bureaucracy, clarify responsibilities, and make the renovation and reactivation of buildings simpler and more efficient.

² Practice-oriented collaborative formats in which public administrations, policymakers, property owners, and civil society work together to test new measures. Policy instruments, incentives, or processes are piloted on a small scale, evaluated, and further developed if they prove successful.