Vernacular architecture offers a viable and underutilized framework for addressing the sustainability failures of contemporary construction in India. Through a comparative literature review and analysis of documented case studies from Kerala, Rajasthan, Assam, and Ladakh, this study finds that traditional building systems consistently achieve lower embodied energy, superior passive thermal performance, and stronger cultural continuity than their modern counterparts — without reliance on mechanical systems. The study also critically examines the limitations of vernacular methods, including structural vulnerability, maintenance demands, and inability to scale in rapidly urbanizing contexts. It concludes that a hybrid model — integrating vernacular passive design, traditional materials upgraded through modern engineering, and digital fabrication tools — presents the most feasible pathway to a sustainable built environment in India.