Which Energy Audit is Right for Your Facility?
An energy audit systematically identifies and develops opportunities to help reduce energy use in an institutional or commercial facility and, as a result, decrease building operating costs. Focusing the audit is imperative for maintenance and engineering managers.
Determining the areas and systems to include in an audit depends partly on the resources an organization is willing to invest in energy efficiency, the facilities' complexity, and the amount of detail and analysis desired from the audit. Understanding these factors will help managers select the audit level that fits the needs of the building and organization.
ASHRAE developed guidelines on energy audits in its paper The Procedures for Commercial Building Energy Audits, which describes a preliminary analysis of energy use and three levels of audits. The guide also details uniform means of reporting building, system, and energy-use characteristics, as well as analysis results. The three audit levels are:
- Level I, walk-through analysis
- Level II, energy survey and engineering analysis
- Level III, detailed analysis of capital-intensive modifications.
The guide describes a preliminary energy-use analysis, which is a precursor to the audit. This procedure analyzes historic utility use and cost, then develops the energy utilization index (EUI) of the building and its systems. The analysis compares the EUI to similar buildings to determine if further engineering study and analysis are likely to produce significant energy savings. When used for comparison between functionally similar structures, this value indicates relative building efficiency.
The preliminary energy-use analysis is the broadest form of energy audit and does not recommend energy-conservation measures. At a minimum, managers can better understand: the energy and cost index for each fuel or demand type; the comparison of the building's EUI to similar buildings; target energy, demand and cost indices; and related energy and cost savings if the facility meets targets.