Novel method for benchmarking the energy performance of industrial refrigeration facilities

Abstract

An alternative "bottom-up" approach is proposed as a novel and sustainable method for benchmarking the energetic performance of industrial refrigeration facilities. The limitations of conventional benchmarking are highlighted and summarized with real case studies. The research presented reveals the primary energy components within specific types of industrial refrigeration facilities which include both refrigeration energy and non-refrigeration energy. Unlike the conventional method which considers the total facility consumption, the proposed method splits the refrigeration energy into two secondary components: Essential Energy and Wasted Energy. Essential energy represents the minimum energy required to satisfy a facility's essential refrigeration load. With the essential energy defined, an energy performance metric called Benchmark Energy Factor (BEF) is introduced. The unitless BEF of a facility compares the actual energy used by the refrigeration system relative to the minimum energy required to satisfy the essential needs of the facility. Unlike conventional performance metrics, the BEF is a normalized performance indicator which takes into account the variable independent parameters unique to each facility. An essential energy model is introduced and used to calculate the essential refrigeration load and the essential refrigeration energy for a given facility. Analyses of 10 facilities are presented, which does a comparison between the postulated performances of the facilities based on conventional benchmarking methods, and the proposed essential energy benchmarking using the benchmark energy factor. The analysis suggests that the conventional method does not accurately reflect the actual performance of the facility. On-site data collection, detailed history of demand side management activities and actual measurement and verification data for all 10 facilities revealed the true top and poor performing facilities which coincided closely with the proposed performance metric. Selected facilities are benchmarked before and after energy conservation measures were implemented, and the proposed essential energy benchmarking methodology is used to calculate the total energy savings achieved. The calculated energy savings are then compared against actual measured and verified energy savings. The analysis demonstrates that the proposed essential energy benchmarking can accurately estimate energy savings of implemented energy conservation measures and may be a more cost effective approach than traditional measurement and verification activities. Canadian Utilities and Natural Resources Canada used the outcomes of this research in setting a new Canadian Standards Association standard: "C500 - Guide on monitoring and energy performance measurement of industrial refrigeration systems using benchmark energy factor concepts".