Metrics Terminology

To clarify how the terms are used in this project, a list of terms related to performance metrics are defined with examples and comments at the end of this document. The definitions are derived from common practice and the Merriam-Webster Dictionary.

Baseline — a standard reference case used as a basis for comparison Examples: a simulation model of a ASHRAE 90.1 compliant building, a control building, measurement of energy consumption prior to application of an energy conservation measure Comments: Establishing a clearly defined baseline is important and defining a repeatable baseline is essential if the work is to be compared to results of other work.

Benchmark — a standardized problem or test case that serves as a basis for evaluation or comparison (Merriam-Webster 2004) Examples: see examples under Baseline Comments: The terms Benchmark and Baseline are often used interchangeably.

Benchmarking — the act of comparing a performance metric to a benchmark or baseline Examples: ENERGY STAR® for buildings, LEED energy credits Comments: Consistent and repeatable benchmarking requires clearly defined performance metrics and protocols for developing the reference case to serve as the baseline.

Building Performance Index — A high level indicator of the performance of a building Examples: BPI is often used to refer to the energy use intensity Comments: There is no standard definition of this term. It is sometimes used to refer to the energy use intensity and sometimes used to account for many different factors (energy, environmental, economic, etc.) into one term. This term is not used in this project at this time because it is not specific and can lead to confusion.

Design Guideline — a set of rules and strategies to help building designers meet certain performance criteria such as energy efficiency or sustainability Examples: AHSRAE Green Guide, LEED, and BREEAM Comments: Although LEED and BREEAM are technically rating systems for new construction, they are often used as design guidelines for new buildings.

Energy Audit — A systemized approach to measuring, recording, and evaluating the operating performance of a building or building system with the intention of improving the performance Examples: ASHRAE's Guide for Commercial Building Energy Analysis

Index — a number (as a ratio) derived from a series of observations and used as an indicator or measure (Merriam-Webster 2004) Examples: Consumer price index Comments: An index is usually taken as a percentage.

Indicator — a parameter, or a value derived from a set of parameters, that points to, provides information about and/or describes the state of a phenomenon. It has a significance beyond that directly associated with the parameter value. (Flanders 2000) Comments: "Indicators are one of many tools for simplifying, quantifying, and communicating vast amounts of information in ways that are more easily understood. They are also useful for alerting us to what areas that need more attention, as well as areas that see improvement." U.S. Interagency Working Group on Sustainable Development Indicators, Council on Environmental Quality, (1998 report pending). From the Presidents Council on Sustainable Development Final Report

Measurement and Verification — refers to the process of examining and proving the results of implementing energy and water conservation measures Examples: International Measurement and Verification Protocol, ASHRAE Guideline 14

Metric — a standard of measurement (Merriam-Webster 2004) Examples: area, insolation Comments: A performance metric is a metric of some performance characteristic; however, not all metrics are performance metrics. For example, area is a metric but it is not a performance metric.

Performance Goal — a specific statement of a desired level of achievement Examples: Reduce annual building source energy consumption by 10% compared to year 2000. Comments: Performance metrics should be carefully chosen to measure progress toward performance goals.

Performance Index — a number (as a ratio) derived from a series of observations and used as an indicator or measure Comments: A performance index is a secondary level performance metric. Performance index is not used in this project to avoid introducing more terms than are necessary.

Performance Indicator — a high-level performance metric that is used to simplify complex information and point to the general state of a phenomenon. Examples: Average Building Energy Use Intensity for all office buildings, Number of Buildings with Daylighting Controls Comments: Performance indicators are used to communicate general trends and are often used on a program planning level to show progress toward goals. See the definition of indicator for more discussion.

Performance Metric — a standard of measurement of a function or operation Examples: Building Energy Use Intensity (BEUI), Net PV System Production, and Lighting Power Density Comments: Performance Metrics should measure and communicate progress toward achieving Performance Goals. There are different levels of performance metrics. The Performance Metrics Project is generally concerned with the primary level, which is the lowest level. The primary level performance metrics are applicable to a specific project, such as the BEUI and end use energy break down. Secondary performance metrics are often combinations of lower level performance metrics and other data, and they are used to show performance of a group of buildings or across an entire building category. An example of a secondary performance metric would be the gross energy intensity of a group of office buildings.

Performance Objective — a general statement of desired achievement Reduce building energy consumption, reduce emissions related to building operation Examples:

Procedure — a standard method or set of methods for determining one or more performance metrics Examples: Procedure for Measuring and Reporting Commercial Building Energy Performance, Procedure for Measuring and Reporting the Performance of Photovoltaic Systems in Buildings Comments: This is one of the primary products of the PMP.

Protocol — a detailed plan of a scientific or medical experiment, treatment, or procedure (Merriam-Webster 2004) Examples: International Performance Measurement & Verification Protocol Comments: Protocol is often used interchangeably with procedure; however, protocol usually infers something that is officially recognized as a standard.

Rating System — a system of rules for comparing the performance of a whole building or building system to benchmarks Examples: ENERGY STAR for Buildings, CalArch, LEED, and BREEAM Comments: Some rating systems, such as ENERGY STAR, are designed to rate the measured energy performance of existing buildings, and some, such as LEED, are designed to rate the expected performance during the design stage. In addition, LEED and BREEAM are environmental rating systems and energy is only one part of the rating. One point of confusion is that LEED is often used as a design guide.

References
Flanders, L. (2000). Assistant Director (UN Division for SD) at the conference Sustainable Development of Coastal Zones and Instruments for its Evaluation, Germany, 23-26 Oct. 2000. Merriam-Webster On-Line Dictionary. (accessed January 21, 2004).