The performance metrics defined by the Commercial Buildings Integration Program offer different tiers of information to address the needs of various users. On this page you will find information about the various goals users are trying to achieve by using performance metrics and the tiers of metrics.
Goals in Measuring Performance
Many individuals and groups are involved with a building over its lifetime, and all have different interests in and requirements for the building. Although these interests differ, the value in using metrics reflects a small number of driving factors:
- Controlling energy costs and energy consumption
- Minimizing environmental impacts
- Enhancing the image through marketing
- Improving load forecasting, energy management, and reliability
Tiers of Metrics
Energy performance is measured throughout the life of a building, from design to commissioning to ongoing operations. To be effective, the measurements and resulting analyses should be consistent at all stages. The Commercial Buildings Integration Program (CBI) has defined different levels, or tiers, of energy performance metrics to address this concern. To learn more about the analysis tiers, read Procedure for Measuring and Reporting Commercial Building Energy Performance. You can also view a list of terminology with definitions and examples.
Tier 1 Metrics
The metrics available at Tier 1 represent the most basic level of a procedure yielding fundamental results. General characteristics of a Tier 1 analysis are that it:
- Generally yields only monthly and annual results
- Often requires only existing data, including utility bills, building drawings, and a physical examination (walk-through) of the building
- Typically does not require additional metering equipment
In Tier 1, utility bills and other rapid, inexpensive means of data gathering are used to determine monthly and annual purchased energy, electrical demand, facility energy production, and related metrics. Tier 1 analysis compares annual facility energy performance. A Tier 1 analysis may or may not describe building energy performance, depending on other energy uses at the facility.
Tier 2 Metrics
The metrics available at Tier 2 represent the advanced level of a procedure yielding detailed results. Most analysts who are interested in a detailed examination of a building's performance will perform a Tier 2 analysis. General characteristics of a Tier 2 analysis are that it:
- Yields seasonal, daily, hourly, or subhourly (if appropriate) results
- Yields results itemized by type of end use
- Requires new data to be recorded in addition to existing building data
- Generally employs submetering and a data acquisition system (DAS)
A Tier 2 analysis must be performed for end-use energy totals or predictions of savings from changes in systems. A Tier 2 analysis can require a substantial effort, and its benefits should be weighed against the associated costs.
Managers and policy makers use the data collected in Tier 1 and Tier 2 analysis to derive indicators. Indicators are used to communicate general trends. They are often used to set policy and demonstrate progress toward goals. Indicators are also useful to identify areas of a project that need more attention.