This study develops a novel sustainability assessment methodology for energy systems using life-cycle emission factors and sustainability indicators. The assessment is applied to a hybrid energy system with hydrogen-based storage to meet the energy needs of a small community in southern Ontario. The energy system can meet the heating, cooling, and electrical energy needs of the 50-household community with a 2000 m(2) solar panel, 16 m rotor radius wind turbine, and 4060 kg of stored hydrogen capacity. The Global Warming Potential and Stratospheric Ozone Depletion Potential sub-indicators have the most significant impact on the Integrated Sustainability Index (ISI) of the system. The tolerable level of stratospheric ozone depletion over the time scale for considering sustainability is a critical parameter associated with a lot of uncertainty. The assessment is expected to prove useful as a quantitative, high-level, multi-criteria decision analysis tool for policy and decision makers to evaluate energy system sustainability. Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.