Energy conservation and efficiency are often widely touted as non-controversial, cost-positive methods of reducing energy consumption and its associated environmental effects.  However, past programs to encourage residential energy efficiency and conservation have failed to make an impact.  A growing amount of research identifies energy feedback as a method to provide consumers with the information and motivation necessary to make appropriate energy-saving decisions.  JouleBug is a social, playful, mobile smartphone application designed to help users in the U.S. reduce energy consumption and live sustainably through behavioral changes.   This project initiated the design of an energy feedback system for JouleBug that provides estimates of a user’s energy savings for completing 38 residential energy saving actions.  Mathematical models were developed to estimate JouleBug users’ energy savings for each of the energy saving actions, based on 13 input parameters. A method was developed to aggregate each of the savings actions across various energy end-uses into a summary of the user’s energy savings over a given time period.  Additionally, the energy models were utilized to analyze an average user’s potential energy, cost, and greenhouse gas savings over a year. Research into the design components of effective feedback systems was applied in the context of JouleBug to compliment the engineering work.  The components of frequency, measurement unit, data granularity, recommended actions, and comparisons were examined.  Design suggestions based on these components that utilized the energy models to provide effective energy feedback to JouleBug’s users were proposed.  Finally, this report describes opportunities for future research using simple energy modeling methods to provide effective consumer energy feedback in a mobile smartphone application.