The objective of this paper is to demonstrate the advantages of using a combined heating and power (CHP) system operating at full load to satisfy a fraction of the facility electric load, that is, a base load. In addition, the effect of using thermal storage during the CHP system operation (CHP-TS) is evaluated. A small office building and a restaurant with the same floor area, in Chicago, IL, and Hartford, CT, were used to evaluate the base-loaded CHP and CHP-TS operation based on operational cost, primary energy consumption (PEC), and carbon dioxide emissions (CDEs). Results indicate that, in general, the use of thermal storage is beneficial for the CHP system operation because it reduces cost, PEC, and CDEs compared with a CHP with no thermal storage. The CHP and CHP-TS operation is more beneficial for a restaurant than for a small office building for the evaluated cities, which clearly indicates the effect of the thermal load on the CHP system performance. Copyright (C) 2011 John Wiley & Sons, Ltd.