District Use of ENERGY STAR Portfolio Manager

The ENERGY STAR Portfolio Manager software tool was created by the U.S. Environmental Protection Agency (EPA) to help building owners track and manage energy use in their buildings. Portfolio Manager is the national industry standard for benchmarking energy performance in commercial buildings, and also has applications for building types such as schools and libraries in the pubic sector.

Building owners can benchmark the energy performance of their buildings by entering utility information (typically electricity and natural gas usage) and building characteristics such as size, hours of operation and occupancy into the Portfolio Manager software tool. Portfolio Manager calculates a key benchmark figure: energy use intensity per square foot (EUI) in kBTU/sq ft, for a building over a select period of time. (kBtu/sf represents 1,000 British thermal units per square foot, and is a standard conversion measure for various types of energy such as electricity and natural gas that may need to be compared or considered together.) Arriving at an EUI makes it possible to compare its energy use to previous periods, to other buildings within a portfolio, and to similar buildings nationwide (energy use intensity data is weather-normalized). The average EUI for libraries nationwide, for example, is 246 kBTU/sq ft, very close to the District's average EUI of 250 kBTU/sq ft for its library buildings. The EUI measure takes into account only a building's size and energy use, and a limited number of other physical characteristics. The number of occupants and hours of operation are not taken into account. The District, like EPA, uses "source" energy use information for comparison, which accounts for 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.

National EUI averages are established by the US Department of Energy's Energy Information Administration Commercial Building Energy Consumption Survey (CBECS). EPA also has established an energy rating score for a number of building types such as office buildings, schools, and warehouses, on a 0 to 100 scale. These "ratable" buildings have a larger sample of buildings to be compared against nationally, and the rating takes into account more detailed building information including the number of occupants and operating hours. The energy rating score offers a more finely tuned result that takes into account how a building is used. An energy rating score of 50 designates a building that performs at exactly the national average for its type, with 50% of buildings performing better and 50% performing more poorly for energy use. Building owners whose buildings earn an energy rating score of 75 or above can earn the ENERGY STAR label, indicating that they are in the top 25th percentile for energy performance nationwide. The Reeves Center complex, for example, has an energy rating score of 65, placing it well above the national average for office buildings but not efficient enough in its energy use to earn an ENERGY STAR label.

Local municipal buildings such as those in the District portfolio are quite different from the large, newer commercial buildings typically benchmarked with Portfolio Manager. A community center, for example, may include multiple uses such as gathering spaces, computer labs, training rooms, and kitchens with or without refrigerators. It may, like a school, combine an array of after-school activities ranging from library operations to boys and girls clubs. Such complex and rich uses in buildings made the Portfolio Manager benchmark process more lengthy and cumbersome, but District staff was able to arrive at reasonable results for most buildings. Some municipal buildings, such as the DC Armory, police training centers, fueling stations, fleet maintenance facilities and the DC Jail do not have categories or national averages under Portfolio Manager. These were incorporated into an "other" category which included EUI numbers but no comparisons. Benchmark results will be followed up with building condition assessments and energy audits to reach more comprehensive results for energy efficiency.