EUI, or energy use intensity, is a unit of measurement that describes a building’s energy use. EUI represents the energy consumed by a building relative to its size.*
A building’s EUI is calculated by taking the total energy consumed in one year (measured in kBtu) and dividing it by the total floorspace of the building. For example, if a 50,000-square-foot school consumed 7,500,000 kBtu of energy last year, its EUI would be 150. A similarly sized school that consumed 9,000,000 kBtu of energy last year would have a higher EUI (180) to reflect its higher energy use. Generally, a low EUI signifies good energy performance.
Certain building types will always use more energy than others. For example, an elementary school uses relatively little energy compared to a hospital. Similarly, a small office building that supports 80 workers will use less energy than a skyscraper that supports thousands. To help you understand where each contestant stands, here are some rules of thumb for typical EUI values:
|Building Type||Average EUI 1|
|Medical Office Building||134|
1 EUI values are presented in kBtu/ft2
Of course it’s not fair to compare these buildings directly to each other, so they will be judged on the percent reduction they achieve in their EUI. A building that reduces its EUI by 15% will do better in the competition rankings than a building that reduces its EUI by 6%, even if that building’s EUI was lower to begin with. EPA will also adjust this percentage to account for changes in weather to ensure that no building is credited or penalized due to changes in weather over the course of the competition.
* Here, EUI refers to source energy use intensity. Source energy represents the total amount of raw fuel that is required to operate the building. It incorporates all transmission, delivery, and production losses, thereby enabling a complete assessment of energy efficiency in a building.
Source: Commercial Building Energy Consumption Survey (CBECS), 2003. The data is gathered from the Dept. of Energy’s Energy Information Administration (EIA) and can be found at http://www.eia.doe.gov/emeu/cbecs/contents.html. Please note all source EUI values displayed are annual figures.