This book explores the legal barriers to energy modernisation in Germany's residential building sector, especially when low-income tenants are involved. It also examines potential solutions to the landlord-tenant dilemma and how they may be applied within the German legal framework. The book conducts an in-depth examination of the regulations, economic factors, and social dynamics that impede progress in energy efficiency improvements. Drawing upon extensive research, comparative case studies, and insights from the Swedish experiences, this book provides a comprehensive analysis of the challenges and opportunities surrounding the decarbonization of dwellings occupied by low-income tenants in Germany.  The book explores the concept of energy poverty in Germany and Sweden, and how these countries address it (or don't) within their legal frameworks. It delves the reader into the complexities of German and Swedish legal systems and how they impact the ability to address energy efficiency in low-income housing. The reader can explore the landlord-tenant dilemma and the hurdles faced when trying to invest in energy modernization, with a special focus on low-income tenants.  This book takes an in-depth look at the legal landscape, exploring both EU policies and national regulations. Sweden's experience, especially its use of municipal green bonds to finance energy transition projects, offers a valuable lesson for Germany. Drawing on comparative insights from Sweden, which has made strides in addressing similar issues, the book aims to identify transferable legal strategies to facilitate energy transition in the rental housing market. By dissecting the intricacies of regulations and legal frameworks, this book offers innovative solutions that can bridge the gap between climate goals and the realities faced by low-income tenants.  This book is intended for a diverse audience, including policymakers, legal professionals, researchers, academics, environmentalists, housing authorities, and advocates for social and climate justice. It serves as an essential resource for those seeking a deeper understanding of the legal complexities surrounding energy modernization in low-income tenant-occupied dwellings and the pathways to surmount these barriers. It serves as a comprehensive resource for those dedicated to dismantling legal barriers to energy efficiency and advancing social and environmental equity.