Biomass is a major source of fuel in many developing countries and used in cook stoves. The water boiling test or its variants are used to evaluate the performance. The evaluation is on an average basis throughout the test and does not provide the dynamics of the energy transfer process. To provide a better insight on this transfer process, the present study demonstrates energy utilization test, which enables analysis of the performance parameters with respect to time. The WBT experimental set up is modified to measure the variation of biomass fuel consumption and water evaporation separately with time by incorporating the separate top mounted weighing balance. The new variable, weight of the water pot, variation with time is also observed along with other standard WBT variables. This new test is validated by performing several experiments. It provides insights on the time-dependent behavior of thermal efficiency and other parameters when performed at different air flow rates. Based on the test results, a new air flow recipe is developed which provides better performance and outlines the significance of energy utilization test. With the formulated recipe, the runtime has improved to nearly 85 min which is an increase of more than 30%. (C) 2018 Elsevier Ltd. All rights reserved.