The estimated annual energy use totals should be derived using a whole-building energy simulation model. The model inputs must include all intended/predicted energy use from all fuel sources (electricity, natural gas, steam, chilled water, propane, etc.).
Because the EPA tools are comparing the predicted annual energy totals to actual performance data, it’s imperative that the energy model include realistic expectations of operating patterns in order for the tools to provide meaningful results. Avoid using default values for the final inputs unless they truly match the operating intent. The model must also account for all regulated loads (equipment and systems), non-regulated loads (plug loads and process loads) and the effect of energy use once the systems are scheduled to perform the functions necessary for the occupants to use the building.
For example, the energy model and predicted estimated energy use for an office building should be calculated based on the expected values for weekly operating hours, number of workers, and HVAC/lighting schedules at the building instead of default values from an ASHRAE 90.1 baseline building or any other generic assumptions. For more information, please see the ENERGY STAR Tips for Effective Energy Analysis of Commercial Building Designs.