Thermal Modernization for Sustainable Cities: Environmental and Economic Impacts in Central Urban Areas

Maintaining a high-quality urban environment remains a critical yet challenging issue in modern cities, particularly in densely built and historically significant central areas. In response, the European Green Deal initiative aims to promote sustainable urban development. This study presents a multi-criteria assessment methodology for evaluating urban environments, with a focus on prioritizing thermal renovations of buildings to achieve substantial environmental improvements. The research adopts a centrifugal strategy, targeting buildings with the poorest energy performance for phased renovation efforts. Using the model city of Gubin, Poland, as a case study, the assessment proceeds through five stages: evaluating technical wear (Stages I–II), estimating replacement values and renovation costs (Stages III–IV), and finally, quantifying environmental benefits from energy efficiency upgrades (Stage V). Findings reveal that buildings in the lowest energy class (Class G) require investments of 111–193% of their replacement value but can deliver CO2 emissions reduced to 1/6.2 of the original level (an approximate 84% reduction). The primary contribution of this paper is the development and application of a novel multi-criteria assessment methodology for evaluating urban environments, specifically designed to prioritize thermal renovations in central urban areas to achieve significant environmental and economic benefits. The study provides valuable economic and environmental indicators that can guide the formulation of pro-environmental urban policies and support strategic decision-making in cities with dense populations and aging infrastructure.