This document discusses energy efficiency reforms in Ukraine's building sector. It finds that Ukraine's heating sector is highly inefficient compared to EU countries, consuming over 2x more energy per square meter. Success requires coordinated action in 3 pillars: legislation, financial mechanisms, and communications. Estimates suggest reforms could save over $5 billion annually through reduced subsidies and gas imports while creating thousands of new jobs. Key actions proposed include establishing an S2I Fund to finance projects, prioritizing thermoregulation and insulation, and expanding the role of municipalities in initiating and administering efficiency projects based on Lithuania's successful model. Significant financing sources were also identified to support municipal energy efficiency projects.