An energy demand load analysis of the 2001 Cafeteria complex, at the University of Lagos, with the budget of a feasible supply of biogas from a bio-degradable food waste using a downdraft bio-digester, is conducted. A walkthrough energy audit of all the appliances that are installed or operated within the complex and the thermophysical properties of the building envelope toward achieving the ASHRAE standard for thermal comfort and indoor air quality, is considered. The design and optimization process, involving collection, storage and management of the food waste from about twenty vendors operating inside the complex, is proposed. Using a standardized performance index for a conventional downdraft bio-digester, the level of dissatisfaction of occupants in each of the energy stocks within the 2001 Cafeteria is presented. The results are useful for the estimation of the economic and environmental impact assessment of a proposed development of a compact solar bio-reactor for independent generation and storage of hydrogen and the estimation of the thermal comfort of the occupants in the building, using an improved Predicted Mean Vote (PMV) model.