Termatics is an Earth Observation (EO) spinoff from the University of Salzburg. We introduce Thermopolis (TRL-2), a city-scale 3D urban thermal digital twin designed to accurately categorize buildings based on their thermal performance. This tool will support the prioritization of renovations towards net-zero emissions and compliance with the Energy Performance of Buildings Directive. Our expertise in AI, geoinformatics, and geovisualization, enables large-scale and high-resolution thermal mapping. By mapping heat patterns from cities, we can also identify potential losses in district heating networks and evaluate the effectiveness of urban greening measures. Utilizing satellite-based and proprietary mobile thermal mapping – we deliver precise, cost-effective, and detailed building heat data for smarter, greener cities.