comparison of reported and evaluated savings, the evaluators generally revised the vetted vendor’s analysis approach with trended and metered data. In some cases, the evaluators created an original analysis approach when the vendor analysis was deemed insufficient or impractical to update. 3.3.3.2 Refrigeration Head Pressure Controls (Electric) The evaluation sample included 4 RCx projects with refrigeration head pressure optimization measures at grocery stores. During the site visits, field engineers inspected refrigeration control panels to document setpoints such as suction pressure, condenser pressure, and condensing temperature differential with the ambient temperature. Temperature loggers were deployed on refrigerant pipes located at compressor discharge or condenser drop leg, and trended data was gathered from the facility’s refrigeration control system on outdoor air temperature, condensing temperature setpoint, and actual condensing temperature. The evaluators obtained the vendors’ savings analyses, which leveraged a custom software tool developed for modeling refrigeration systems. The software simulates the hourly energy use of the compressors and condensers based on thermodynamic and heat transfer calculations. The evaluators reviewed the applicant software analysis methodology and determined it to be appropriate for this measure category. For the most unbiased comparison of savings, the evaluated energy savings were calculated using the applicant’s savings analysis software tool, updated with actual compressor and condenser system performance metrics from trended and metered data. Discrepancy Analysis The primary objectives of this include identifying why the evaluated gross savings estimates differ from the program-reported savings estimates. The evaluators completed separate discrepancy analyses for the following five program-measure combinations: Steam trap O&M, RCx Electric, RCx Gas, PRIME, and Electric O&M projects. The various discrepancy categories considered within each discrepancy analysis are summarized in Table 3-4 and are defined further in Appendix A. The discrepancy categories are customized for the various BES programs and measures to most appropriately tailor the evaluation findings and recommendations to the programs. Table 3-4. Discrepancy Categories for BES Programs and Measures Program / Measure Category Discrepancy Categories
The revised method and model coefficient values led to a 27% reduction in evaluated natural gas savings, compared with the PSD approach for the same project. Differences in steam conditions between those assumed in the applicant analysis and observed by the evaluators on-site was the next highest contributor, resulting in an overall 11% increase to the evaluated O&M natural gas savings. For 3 projects in the sample, the evaluators observed higher steam pressure at the traps than stated in the project application, leading to higher savings from trap repair/replacement. The evaluators encountered decommissioned steam traps during the site visits, which resulted in a 7% reduction to the evaluated O&M natural gas savings. For 3 out of the 18 evaluated steam trap projects, the evaluators found one or more claimed steam traps to be decommissioned, leading to lower evaluated savings than anticipated. Retro-Commissioning Program (RCx) In order to contextualize this study’s findings with prior evaluation results, Table 4-9 compares key evaluation criteria and findings for RCx with the prior impact evaluation completed in 2013. Table 4-9. Comparison of Key Criteria and Findings with Prior Impact Evaluation for RCx Parameter Impact Evaluation Report Year Program Profile 2013 2018 Study period (program years) 2008-2010 2015 Average reported annual savings (kWh) 1,955,185 4,845,471 Average annual number of electric sites 6 16 Average annual reported electricity savings/site (kWh) 345,033 302,842 Average reported annual savings (MMBtu) 2,500 8,463 Average annual number of gas sites 1 10 Average annual reported gas savings/site (MMBtu) 1,875 846 Evaluation Approach Method(s) Census M&V Census M&V Results ‒ RRs Electric energy 74% 105% Summer seasonal peak demand 113% 126% Winter seasonal peak demand 90% 175%