20C Freezer Evaluation

Laboratories remain one of the best candidates for energy efficiency. After data centers, laboratories consume more energy per square foot than any other type of facility. This is due to their energy-intensive equipment, around-the-clock operations, and uniquely demanding heating, ventilating, and air-conditioning (HVAC) requirements. A 2015 study conducted by the Center for Energy Efficient Laboratories (CEEL) identified a minimum of 116 million square feet of laboratory space in California in just the academic, life science research, and hospital market sectors. During this study a substantial, untapped opportunity for energy savings in California’s laboratory plug loads, which were found to comprise ~2% of commercial electrical consumption in the state, or up to ~3 billion kWh/year was uncovered. This report constitutes the next critical step in a widespread multi-year effort to realize savings from laboratory plug load reductions. The study extends previous work on laboratory refrigeration to examine opportunities for energy efficiency in -20°C freezers. The 2015 CEEL study found that California is home to at least 74,000 -20°C freezers, consuming an estimated 100-300 million kWh/year. This product category is further subdivided by the Environmental Protection Agency (EPA) into ‘laboratory-grade’ and ‘highperformance’ -20°C freezers, defined in terms of allowable levels of temperature variation. High-performance freezers have been the focus of energy-efficiency efforts to date, with 19 models meeting the EPA ENERGY STAR® program criteria. Laboratory-grade freezers have not received this level of attention; no models are currently ENERGY STAR-certified. Preliminary data indicates that laboratory-grade freezers consume between 1 and 15 kWh/day depending on the model, suggesting that there is strong potential differentiation in this category. This Emerging Products study seeks to evaluate the installed base of laboratory-grade freezers to identify energy-efficient models that can be recommended for the ENERGY STAR program. The energy performance of 47 laboratory-grade freezers was evaluated at seven field test sites in Southern California. The collected field data were inconclusive, and the scope was expanded to include tests of two additional freezers in a controlled environment test facility. The additional testing of energy and temperature performance, using the ENERGY STAR test method for laboratory refrigeration, helped to clarify the field results. The findings of these tests illuminated a previously-overlooked nuance of the laboratorygrade freezer product category: it is, in fact, comprised of two distinct product subcategories. The CEEL named these two categories ’general purpose (GP) and ’enhanced general purpose’ (EGP). GP freezers consume significantly less energy than EGP freezers. They also exhibit less thermal stability. EGP freezers use ~4 times more energy than GP freezers, but the internal temperature of these freezers is more stable. This distinction is also recognized by scientists, whose responses to a CEEL market study indicate that they intentionally purchase EGP freezers to store valuable samples presumed to be sensitive to thermal fluctuations (e.g., tissue, DNA), whereas the purchase of GP freezers is often based on cost considerations for the storage of samples presumed to be unharmed by storage temperature variations (e.g., serum, enzymes). It was found that all GP freezers consume approximately the same (relatively small) amount of energy. EGP freezer energy consumption was found to be more variable; however, EGP freezers are typically designed with the ability to operate below -20°C, with some freezers being able to maintain temperatures down to -30°C and others to -40°C. On average, EGP freezers capable of maintaining temperatures to -40°C consumed more energy than those capable of maintaining temperatures to -30°C. More variability in energy consumption was observed for those EGP freezers capable of maintaining temperatures to -40°C. However, the observed variability was not due to energy-efficient technology; the same model of freezer was seen to exhibit a two-fold difference in energy consumption between units. While these findings explain previous reports of vast differences in energy consumption among -20°C freezers, they do not support the hypothesis that there are energy-efficient GP or EGP freezers available on the market. Furthermore, this study shows that while the majority of the estimated 74,000 laboratory-grade freezers in California are GP freezers (65% by number), collectively the EGP freezers consume twice as much energy. These results can also be used to update the previous estimate for the total energy consumption of laboratory-grade -20°C freezers in California; the 74,000 freezers consume a total of ~84 million kWh/year. The results of this study were unexpected. All previous data pointed to the existence of energy-efficient technology in this product space. Because this was ultimately not the case, this report functions as a detailed summary of the installed base and a catalyst for the restructuring of the ENERGY STAR categories to reflect the GP/EGP distinction. When energy-efficient technology becomes available, it should then be a simple process to obtain an ENERGY STAR rating. The market study and HVAC modeling study also conducted as part of this report provide useful data for the development of an incentive program should energy-efficient freezer models become available. Natural refrigerants are becoming more widely adopted and are now used in Ultra-low Temperature (ULT) freezers and commercial grade foodservice freezers. The -20°C laboratory-grade freezer market has not yet adopted R290 natural refrigerant; most of the current units run on R404. However, it is feasible for the laboratory freezer industry to shift to natural refrigerants. This shift may lead to system redesign with an emphasis on energy efficiency. In the absence of technological advances, the investor owned utility (IOUs) should focus on reducing energy consumption in this product category through education. All customers with laboratories should be made aware of the importance of purchasing the right type of freezer for their application. Although this Emerging Products study evolved into a market study of existing technology, this report can nevertheless be used to drive the market toward greater energy efficiency by providing guidance to the California IOUs, constructive feedback to -20°C freezer manufacturers, and valuable data to those purchasing freezers, designing laboratory facilities, and to the EPA to refine the ENERGY STAR program.