A solar-biomass hybrid power system may be a feasible approach for decarbonizing and achieving a sustainable energy transition in an academic building. This cutting-edge technology generates clean, sustainable power by fusing the advantages of biomass and solar energy. The present research analyses and optimises a Hybrid Renewable Energy System (HRES) for the Department of Mechanical Engineering, Delhi Technological University (located at 28°44' N and 77°06' E). Hybrid optimization model for electric renewable (HOMER) software is employed for simulation, and analysis primarily focuses on the techno-environomic assessment of the system. HRES is designed to fulfil daily energy consumption of 588 kWh at a peak load of 65kW. System generates 3,76,780 kWh of power every year. The cost of energy (COE) is ₹16.96 (US$ 0.207)/kWh and the gross net present cost (NPC) is ₹41,603,969.8 (US$ 5,07,737). Throughout lifetime (25 years), biomass gasifier and solar PV contribute 23.4% and 76.6% of the total energy production. Around 161 metric tons of CO2 is prevented from entering the atmosphere. Therefore, proposed HRES is technically consistent, dependable, economically viable, and environmentally sustainable.