Building Performance Metrics and Definitions – an Overview

The drive towards sustainable, low-energy buildings has increased the necessity for easy, yet accurate methods to gauge whether the building meets minimum standards for energy performance and human comfort. A key barrier to widespread adoption of sustainable design is the lack of availability of actual, measured performance information for sustainably designed and operated buildings.

Building energy performance assessment is crucial to ascertain the efficiency of energy use in buildings and is the basis for making decisions for enhancing energy efficiency. To assess the energy performance of existing buildings quantitatively, the energy use of the assessed buildings should be quantified first. The quantified energy use will be then used to compare with available assessment criteria, standards or benchmarks to determine the energy performance quantitatively.

This article, published on ISHRAE, aims to identify key performance indicators (KPIs) representing major and consistent variables affecting building energy use. The top-down approach to performance analysis begins with the whole-building annual benchmarks. This is drilled down to the system level and then to granular details around component performance that make up for the system. In a building, the ‘system’ refers to an aggregate total of all usage, electric or fuel, by a category of kit. Frequently used categories are HVAC, lighting and plug loads, with additional categories depending on the level of details of measurements. This article reviews building energy performance evaluation metrics at the whole-building, system, and individual equipment or component levels.