Providing ancillary services through flexible load response has the potential to increase electric grid reliability and efficiency while offering loads a revenue generating opportunity. The large power draw of commercial buildings, along with thermal mass characteristics, has sparked interest in providing ancillary services through intelligent operation of building mechanical systems. As a precursor to participating in ancillary service markets, the quantity of service available must be estimated. This work presents a model-based approach for estimating commercial building frequency regulation capability. A model predictive control framework is proposed to determine optimal operating strategies in consideration of energy use, energy expense, peak demand, economic demand response revenue, and frequency regulation revenue. The methodology is demonstrated through simulation for medium office and large office building applications, highlighting its ability to merge revenue generating opportunities with traditional demand and cost reducing objectives. (C) 2014 Elsevier B.V. All rights reserved.