A new model for predicting the thermal and electrical performance of solid-oxide fuel cell(SOFC) cogeneration devices for residential buildings has been developed and demonstrated. This is a system-level model that considers the thermodynamic performance of all components that consume energy and produce the thermal and electrical output of the SOFC-cogeneration device. The model relies heavily upon empirical information that can be acquired from the testing of coherent systems or components and is designed for operation at a time resolution that is in the order of minutes. Hence, it is appropriate for use in whole-building simulation programs, where it can be applied to assess the energy and greenhouse gas emission benefits of this nascent technology.