On occasion, a dropped network connection or an inappropriate house description can cause the DOE-2 engine to experience failure. The Home Energy Saver has error traps in place to prevent the loss of data in a situation where there is a DOE-2 failure. After the results of the DOE-2 run are returned to the web application, the returned energy consumptions are tested for valid values. If an error is detected, the web application discards the returned values, continuing the calculation with the previous energy consumptions for heating and cooling. If results are not returned from DOE, the application again reverts to previously stored data.