A System Dynamics model specially built to analyze residential energy policies is presented. The model allows to simulate substitution of household equipments for more efficient ones using two stage economic decision process. In the first stage the user select the most economic alternative and in the second stage the user compares the financial condition to acquire the chosen energy alternative considering his buying capacity during the period of analysis (delays are condidered). The model allows to examine several aspects such as: alternatives on technology diffusion, energy consumption growth and effects of pricing policies on diverse energetic demands. The model was applied to the Medellin Metropolitan Area, Colombia. Results are included.