Numerous strategies exist for crafting indoor environments that not only deliver thermal comfort but also align with well-established principles derived from over a century of research conducted in both laboratory and field settings. This extensive body of work spans multiple disciplines, including psychology, psychophysics, biophysics, and physiology. However, despite the profound under-standing of the factors contributing to thermal comfort, there remains a notable gap in exploring the complex relationship between thermal comfort, energy consumption—particularly in buildings—and sustainability. This chapter explores the concept of thermal comfort and highlights its pivotal role within the building sector. Additionally, it examines the contemporary trend of using eco-friendly insulation materials in construction. While the basics of thermal comfort have been thoroughly studied, the intersection of designing for comfort and achieving sustainable building practices remains relatively underexplored. As we delve into these aspects, it becomes evident that the synergy between thermal comfort and sustainable building practices is an evolving area that warrants further investigation. This article offers a comprehensive review of modern eco-friendly insulation materials, particularly those derived from natural or recycled sources. Through a comparative analysis with conventional insulation options, the re-search highlights the benefits and challenges of these emerging materials. The study concludes with key insights into the evolving relationship between thermal comfort, thermal conductivity, and sustainable building practices, emphasizing the need for continued exploration in this field.