The renovation twin: a digital breakthrough to unlock large-scale energy renovation 

The Energy Agency of Plovdiv (EAP) is redefining how cities can accelerate residential energy renovation through its Digital Renovation Twin for Plovdiv City. Built on a robust Geographic Information System (GIS), this pioneering platform combines dynamic 3D visualisations of residential buildings with interactive decision-support tools, empowering homeowners while strengthening the city’s renovation ecosystem. 

Over the past decade, renovation rates in the Plovdiv Region have remained critically low, with fewer than 0.5% of dwellings upgraded. Progress has largely depended on national grant schemes, leaving limited room for informed private investment and proactive decision-making by homeowners. The Renovation Twin was developed to break this deadlock. By placing reliable, building-specific information directly in the hands of citizens, EAP aims to transform renovation from a complex, opaque process into a clear and actionable pathway. 

At the centre of the platform is an intuitive self-service tool called the Renovation Motivator. It allows homeowners to instantly visualise their building’s current energy performance and explore the impact of different renovation scenarios. Through simplified outputs and clear visual comparisons, users can understand potential energy and cost savings in just a few clicks. In doing so, the tool lowers entry barriers, builds confidence, and supports more informed renovation decisions at an early stage. 

The innovative character of the 3D Renovation Twin has already gained international recognition. In 2025, it was awarded at the City Lovers competition, which highlights pioneering urban solutions. The jury recognised the platform as a concrete example of how digital tools can modernise residential renovation markets and support a new generation of data-driven urban planning. 

A living energy performance model built for scale 

Developing the Renovation Twin required overcoming significant data gaps. To do so, EAP consolidated building-level information from multiple sources into individual Digital Building Logbooks, creating a comprehensive and evolving repository of the local building stock. These logbooks integrate basic characteristics such as construction year and building type with spatial, technical, and occupancy-related data. 

At the core of the system lies an advanced, “living” smart Energy Performance Certificate (EPC) algorithm, developed entirely in-house by EAP. Unlike conventional static EPCs, this algorithm continuously improves as new data is added to the logbooks. It dynamically refines performance estimates and renovation scenarios, ensuring increasing accuracy over time. By translating complex datasets into accessible insights, the algorithm powers the Renovation Motivator and provides homeowners with realistic previews of energy, cost, and emission savings. 

From digital innovation to renovation acceleration 

As the Renovation Twin moves into public deployment, EAP is already expanding its functionality through a modular and scalable architecture. New modules can be added to respond to evolving policy priorities and market needs. A recently introduced solar module, for example, enables homeowners to simulate rooftop photovoltaic production and assess the potential for creating citizen energy communities. 

The Renovation Twin also marks a new phase in the digitalisation of EAP’s one-stop shop renovation services. By centralising data and automating technical and financial pre-assessments, it significantly reduces the time required for initial consultations. What previously took over an hour can now be achieved in minutes, benefiting homeowners, renovation professionals, and public authorities alike. More broadly, the platform demonstrates how digital tools can make renovation processes more transparent, scalable, and accessible, a prerequisite for increasing renovation rates at city level. 

“The Renovation Twin is a first-of-its-kind solution in Bulgaria and a genuinely ground-breaking development. It combines a full-scale building stock observatory with intuitive, user-friendly tools for both homeowners and experts. Our ambition is for this model to inspire more citizens to renovate and to be replicated well beyond Plovdiv.” 
Liyana Adjarova, Executive Director, Energy Agency of Plovdiv 

This best practice is extracted from our publication ‘Sustainable Regions in Action‘. Discover more best practices here!