A building's energy use refers to the energy required to operate and sustain the project once it's occupied. The metric is expressed as the energy per square foot per year (kBtu/ft2/yr), more commonly known as the EUI or energy use intensity. By calculating the energy a building consumes annually, architects can better predict the project's cost as it is directly linked to a building's prospected energy consumption and expenditure.
When running energy simulation one must understand the toll each design decision will take on altering the EUI. Depending on the building assembly, glazing percentages, active and passive strategies implemented, loads, and costs can drastically spike and leave building owners and tenants paying millions more annually. Knowing the EUI values of design decisions and other iterations, one can get the best value for performance. To learn more about the breakdown of EUI, check out this article.
Pro Tip: Cove.tool can help understand the impact of energy and energy cost of specific façade decisions. A user can study the impact of varying glazing percentages, adding overhang, fins, or other façade elements on energy use and costages.