<p>Precast construction provides better quality control, improved site safety, and faster project timelines than traditional RCC (Reinforced Cement Concrete) methods. The push for sustainable building practices has increased in India, yet few studies offer a detailed comparison between conventional RCC buildings and modular alternatives. This study addresses that gap by conducting a comprehensive life cycle energy assessment (LCEA) of both construction types (Traditional RCC building and Light gauge steel frame (LGSF)-Ferron Modular Building in a mid-rise residential project in Maharashtra. Using a hybrid approach that integrates process-based and input–output methods, the study evaluates embodied, operational, and demolition energy, offering valuable insights into the energy efficiency of modular construction in the Indian context. Findings show that operational energy accounts for ~ 83% of total life cycle energy, followed by embodied (~ 15%) and demolition (~ 2%). The LGSF-Ferron building consumes 11.06% less life cycle energy (18,486.54 MJ/m²) than RCC (20,787.26 MJ/m²), mainly due to reduced embodied energy. This difference is specific to the case study and may vary with regional factors. The study provides evidence-based insights into material choices, construction methods, and energy-efficient strategies that contribute to India’s sustainable development goals. However, broader sustainability claims require further analysis of additional environmental impacts. The study also offers actionable insights for architects, engineers, and policymakers to explore energy-efficient modular construction, contributing to sustainable development in India.</p>