Source of Performance Comparison Data
The U.S. Department of Energy’s (DOE) Building Performance Database (BPD) is the nation’s largest dataset of information about the energy-related characteristics of commercial buildings, including more than 230,000 commercial building across the country. The BPD combines, cleanses, and anonymizes data collected by federal, state, and local governments, utilities, energy efficiency programs, building owners and private companies.
The BPD includes data across real estate sectors and regions and enables comparison of various physical and operational characteristics to gain a better understanding of market conditions and trends in energy performance. Building characteristics and energy consumption data can be used to compare similar buildings, i.e., same use type, and identify under-performers. The BPD can be used to analyze trends within custom defined local peer groups for specific real estate sub-markets and to benchmark a subject building’s performance against peer buildings in the same geographical area or climate zone.
The goal of the BPD is to leverage the law of large numbers to achieve performance benchmarking validity at the local level (same geographical area or climate zone), as opposed to a representative national sample as the U.S. Energy Information Administration’s Commercial Building Energy Consumption Survey (CBECS) and EPA’s ENERGY STAR Portfolio Manager (1 to 100 rating), which is based upon the CBECS, is designed to do. For this reason, the BPD is the preferred source of benchmarking data provided sufficient peer buildings are available in the same geographical area or climate zone to confidently determine the median energy use intensity (EUI) of peer buildings.
For multifamily buildings, in addition to the BPD, the U.S. DOE’s Residential Energy Consumption Survey (RECS) is used to benchmark the subject building’s EUI to peer multifamily buildings in the same geographical area, climate zone, or nationally.
Peer Group EUI
The median energy use intensity (EUI) of all peer buildings in the same geographical area or climate zone (Peer Group) is the 50th percentile EUI as determined in the U.S. DOE’s Building Performance Database (BPD) for commercial buildings and Residential Energy Consumption Survey (RECS) for multifamily buildings. In view of the variability that may exist in peer building EUI data, the EPIC Report PDF displays the peer group’s median EUI range, including a variability allowance of 10% in accordance with ASTM E3224 Building Energy Performance and Improvement Evaluation (BEPIE) standard methodology.
Benchmark Energy Performance
To determine if the subject building’s energy consumption is greater than, less than, or at parity with that of its peer group, the building’s weather normalized EUI data is used to benchmark its performance against the peer group’s median EUI range reflecting a 10% uncertainty allowance.
If the EUI of the subject building is less than that of its peer group, it generally would be viewed as more energy efficient and typically have lower operating costs, be more valuable, and be more attractive to tenants, making it more competitive in the marketplace.
If the EUI of the subject building is greater than that of its peer group, it generally would be viewed as less energy efficient and typically have higher operating costs, be less valuable, have a higher risk of obsolescence and be less attractive to tenants, making it less competitive in the marketplace.
For mixed-use buildings, whole building performance comparison with peer buildings is enabled by utilizing the peer group median EUI for each use, determining a weighted (by sq. ft.) whole building EUI benchmark and applying an HVAC adjustment factor to take common floors and ceilings into consideration. For example, in a mixed-use building with two uses: ground floor retail and upper floor office space, the “ceiling” of the retail space would be the “floor” of the office space. The net impact would be less whole building energy consumption than if each use was considered as an independent building, i.e., the whole building EUI would be less than the weighted (by sq. ft.) EUI associated with each use.