Compressed air is typically one of the most expensive utilities in an industrial facility. As a result, potential savings opportunities are aggressively sought out and identified. Once identified, projected energy savings must be calculated in order to justify the cost of implementing the savings opportunity. It is important to calculate projected energy and cost savings as accurately as possible. Unfortunately, savings are frequently overestimated because the methods used to estimate savings neglect to consider important factors such as compressor control and type, storage, and multiple compressor operation.

In this paper, a methodology is presented for modeling air compressor performance and calculating projected energy savings from easily obtainable performance data such as full-load power, no-load power, rated capacity, average fraction full-load power or average fraction rated capacity. The methodology is applied in case study examples that illustrate the difference between estimating savings using this method and rule-of-thumb methods.