Comparing HOT2000 results to actual, metered data.

You have been using HOT2000 to determine if house designs meet the R-2000 energy target and have always believed that it does a good job. One day you decide to model your own home and compare the results to the utility bills. You find that the predicted and measured energy usage differs by a significant amount! Does this sound familiar? What's going on? Why the difference? Does this mean the utility meters are no good (unlikely); that you don't know how to perform take-offs (shudder); or that HOT2000 is no good (shriek)? Don't panic. There are a number of reasons why HOT2000-predicted energy consumption may differ from utility-measured consumption. Most of these are not caused by HOT2000 but in the way the house is interpreted by you, the user, for input to the program.