John Barnes


Ex Ante Reviews

We have wide-ranging experience in performing project baseline assessments and reviews of project energy savings performed prior to project implementation. Below, ADM engineer John Barnes answers some questions relating to ex ante project reviews performed for commercial and industrial energy efficiency programs.

We can help establish reliable understanding of project energy savings and data collection needs throughout the entire program participation process. This may improve participant, particularly if program incentives are depending on achieved energy savings. We can also reduce the likelihood of unexpected findings during the evaluation process.

To give an example: for a project involving the installation of a variable speed drive compressor to be used in a manufacturing setting, the installing contractor provided detailed, one-minute data taken directly from the compressor’s on board control system. The raw data provided by the contractor was unlabeled, and the project’s ex ante energy savings calculation assumed the data was the compressed air cubic feet per minute (CFM) output of the compressor. This CFM estimate was then used to calculate the compressor’s power usage and ultimately energy savings.

During the ex ante review, we interviewed the contractor who had conducted the monitoring and found that the unlabeled data taken from the compressors on board control system was actually compressor amperage data and not CFM data. This discovery drastically changed how the data was used in the energy savings calculation and resulted in a greatly improved ex ante energy savings estimation.

Performing the ex ante review requires a solid understanding of the project scope, the applicable baseline conditions, and how the project will generate energy savings. It also requires identification of the appropriate methods to estimate energy savings with the available data.

Understanding how energy savings will be realized may require engagement with program participant staff. Involving the program participant staff during an ex ante review may be important because they have important information about their systems, processes, and operating conditions. Their insight is key to answering questions early in the evaluation process.

Identifying the appropriate energy savings calculation method during the ex ante review is determined by the measure characteristics and type of data collection that is feasible and that will facilitate the evaluation of energy savings. Certain energy savings methods may not be workable due to the unavailability of information or specific data collection. In these situations, alternative energy savings calculation methods are selected during the ex ante review as opposed to after the project has been commissioned, saving the participant’s and evaluator’s time. Also, the ex ante review helps to inform the participant of expectations about the scope and duration of monitoring and helps the evaluator establish a plan to optimally utilize the available data.

While ex ante review can mitigate risk for many projects, intricate projects with relative high energy savings are best suited to ex ante reviews. Typically, energy savings of more intricate projects are associated with more variables and greater uncertainty regarding energy savings as well as the optimal energy savings calculation method. Through an ex ante review, the variables impacting energy savings and energy savings calculation methods are identified and uncertainty is minimized. The criteria for performing ex ante review varies from evaluation project-to-project, but typically ex ante reviews of relatively few large projects can minimize risk for a significant portion of a commercial and industrial program’s overall expected energy savings. In this way, ex ante reviews can significantly reduce uncertainty regarding energy savings for programs and portfolios as a whole.

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