Energy modeling can be more than simply determining how much heating and cooling a building requires, it can provide unique insights into a building’s full potential. Technical analysis of heating and cooling loads combined with real world economic considerations yields an inventory of sustainable solutions that will determine not only first cost, but the maintenance and operating costs for the life of a building. Energy 1 provides a full-building approach to economically optimize energy and water use that will improve the efficiency of the building well into its own legacy.