Casa Fernández de Muras, a historic building in the heart of the Spanish city of Valladolid, is undergoing a pioneering transformation into a Positive Energy Building (PEB). This initiative seeks to demonstrate how heritage preservation and modern sustainability can coexist, turning an 18th-century palace into a model of energy efficiency. The project builds on lessons from the EXCESS demo case and aims to inspire similar upgrades across Spain and Europe.

The building’s protected status presents regulatory challenges, requiring careful compliance with local, regional, and national laws. Despite these constraints, the structure’s layout and roof orientation make it well-suited for photovoltaic installation and energy-efficient refurbishment. Proposed upgrades include improved insulation, aerothermal heat pumps, and a rooftop solar system capable of producing more energy than the building consumes.

Socially, the project is driven by a community of apartment owners, who are encouraged to form energy-sharing cooperatives. This approach not only reduces costs but also fosters innovation in urban energy management. The initiative promotes the idea of energy communities, enabling residents to trade surplus energy and collaborate on maintenance and sustainability goals.

Financially, the renovation requires significant investment, but various support mechanisms are available. Public subsidies, energy savings certificates, and low-interest loans from the Official Credit Institute (ICO) offer viable funding options. Local governments are urged to support such projects through technical advisory services, visual integration of solar technologies, and dedicated funding schemes to accelerate the adoption of PEBs in heritage contexts.