INTEGRATION OF DEMAND RESPONSE INTO TITLE 20 FOR HOT FOOD HOLDING CABINETS

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1 Design & Engineering Services INTEGRATION OF DEMAND RESPONSE INTO TITLE 20 FOR HOT FOOD HOLDING CABINETS Phase1: Demand Response Potential DR Report Prepared by: Design & Engineering Services Customer Service Business Unit Southern California Edison November 30, 2009 What s Inside Executive Summary... Introduction... Market Size/Barrier... DR Strategies and Potential... Results... Recommendations... References

2 Integration of DR into Title 20 for Hot Food Holding Cabinets DR Acknowledgements Southern California Edison s Design & Engineering Services (DES) group is responsible for this project in collaboration with the Tariff Programs & Services (TP&S) group. It was developed as part of Southern California Edison s Demand Response, Emerging Markets and Technology program under internal project number DR DES project manager Devin Rauss conducted this technology evaluation with overall guidance and management from Carlos Haiad of DES, and Jeremy Laundergan of TP&S. For more information on this project, contact devin.rauss@sce.com. Disclaimer This report was prepared by Southern California Edison (SCE) and funded by California utility customers under the auspices of the California Public Utilities Commission. Reproduction or distribution of the whole or any part of the contents of this document without the express written permission of SCE is prohibited. This work was performed with reasonable care and in accordance with professional standards. However, neither SCE nor any entity performing the work pursuant to SCE s authority make any warranty or representation, expressed or implied, with regard to this report, the merchantability or fitness for a particular purpose of the results of the work, or any analyses, or conclusions contained in this report. The results reflected in the work are generally representative of operating conditions; however, the results in any other situation may vary depending upon particular operating conditions. Southern California Edison November 2009 Design & Engineering Services

3 Integration of DR into Title 20 for Hot Food Holding Cabinets DR ABBREVIATIONS AND ACRONYMS DR PG&E SCE SDG&E Title 20 Demand Response Pacific Gas and Electric Southern California Edison San Diego Gas and Electric California s Appliance Efficiency Regulations Southern California Edison Page i

4 EXECUTIVE SUMMARY This project assesses the demand response (DR) potential associated with hot food holding cabinets and the potential to include DR requirements for hot food holding cabinets in California s Appliance Efficiency Regulations (Title 20). Hot food holding cabinets are capable of responding to a DR event by turning off heating elements. Depending on the configuration of the cabinet, this can result in a complete shut off of the unit, or in reduced heating capacity, if multiple heating elements are present. The DR potential for hot food holding cabinets is dependent on the strategy selected, market size, and acceptance factors. The strategies suggested have the potential to reduce between 300 and 600 W per cabinet, depending on size and strategy. The statewide market size was determined to be 42,000 units, with roughly 23,000 in Southern California Edison s (SCE) service territory. Market acceptance is dependent on usage and insulation levels, but is ultimately governed by the need to maintain food quality and safety. The DR potential for the two strategies identified is shown in Table 1. TABLE 1. DR STRATEGY POTENTIAL SUMMARY STRATEGY MINIMUM POTENTIAL MAXIMUM POTENTIAL SCE CA SCE CA Unit Shut Off ,825 21,500 Use Staging to Reduce Heating Elements This study found that food quality and safety as a function of temperature and time is mostly unknown. However, this is the major driver behind the acceptance of any hot food holding cabinet related DR strategy. Therefore, it is suggested that additional studies be performed to determine this relationship. Additionally, technical feasibility should be demonstrated. Southern California Edison Page 1

5 INTRODUCTION This project seeks to validate and establish demand response (DR) potential for hot food holding cabinets. It is part of a multi-phase, multi-year effort to evaluate the potential for DR to be incorporated into the California Appliance Efficiency Regulations (Title 20) for a series of 13 commercial and residential appliance categories from refrigerated display cases to hot food holding cabinets. This project aligns well with the objective of Southern California Edison s (SCE) SmartConnect TM by fostering and accelerating the availability of DR-ready appliances in the market place. Furthermore, this project supports the California Public Utilities Commission goal of zero net energy for residential new construction by 2020 and commercial new construction by Phase 1 of this potential three-phase effort addresses the DR potential for hot food holding cabinets; if Phase 1 yields encouraging results, Phase 2 will demonstrate DR capabilities and strategies for hot food holding cabinets, and if the demonstration is successful, Phase 3 will develop a Title 20 Codes and Standards Enhancement initiative to incorporate DR requirements for hot food holding cabinets. This report reviews the findings from Phase 1 and estimates the DR potential for hot food holding cabinets. This phase entails assessing the demand reduction associated with hot food holding cabinets, the population statewide and within SCE service territory, and the market/consumer acceptability of DR strategies associated with hot food holding cabinets. TECHNOLOGY DESCRIPTION Hot food holding cabinets are electric appliances used in commercial kitchens and food service applications to maintain food temperature prior to serving, after cooking. These appliances are typically highly mobile, and can be transported to various service locations (e.g., a catering company). According to the California Energy Commission s 2009 Title 20 appliance regulations, a hot food holding cabinet is defined as: a heated, fully enclosed compartment, with one or more solid or partial glass doors, that is designed to maintain the temperature of hot food that has been cooked in a separate appliance. A commercial hot food holding cabinet does not include heated glass merchandising cabinets, drawer warmers or cook-and-hold appliances. 1 These cabinets are constructed of a metal exterior and come with either insulated or non-insulated cabinets. The heating is provided by an electric heating element, or multiple elements depending on the size and design. Additionally, these units can be designed to either have a fan circulating air throughout the cabinet, or without the fan. In either case a temperature control mechanism is included. Although these cases come in a variety of sizes, they can be classified into three basic sizes; small, medium, and large. CURRENT ENERGY CODE REQUIREMENTS Beginning in August 2003, hot food holding cabinets were able to receive the ENERGY STAR certification. In order to achieve the ENERGY STAR designation these cabinets are required to have an energy usage no greater than 40 W/ft 3 in idle mode. Southern California Edison Page 2

6 As of January 1, 2006 Title 20 requires that all hot food holding cabinets sold in the state of California meet the same requirements as ENERGY STAR, 40 W/ft 3. Although this does not preclude uninsulated holding cabinets from being sold, it greatly shifts the market towards insulated cabinets. There are currently no Federal standards associated with the performance of hot food holding cabinets. DEMAND PROFILE AND ENERGY CONSUMPTION The performance of these cabinets is highly dependent on the size and insulation level. As noted these units, regardless of insulation level, are required to use no more than 40 W/ft 3 in idle mode. Therefore, a performance level of 40 W/ft 3 will be used to estimate the demand profile. Energy consumption is dependent on the run time of these units. Using the same assumptions as the rebate programs, 2 the run time is estimated to be 5,475 hours per year. Additionally, the energy and demand are driven by the size of the unit. The ENERGY STAR website provides a list of qualifying products; 3 this list was used to determine three characteristic sizes. For the purposes of this report, these sizes are: small (10 ft 3 ), medium (25 ft 3 ), and large (40 ft 3 ). Table 2 details the demand profile and energy consumption values for these three size cabinets. TABLE 2. DEMAND PROFILE AND ENERGY CONSUMPTION EQUIPMENT SIZE DEMAND ENERGY CONSUMPTION (KWH) Small (10 ft 3 ) Medium (25 ft 3 ) Large (40 ft 3 ) MARKET SIZE Fisher Nickel Inc. recently commissioned a report on the market size and performance of hot food holding cabinets. Unfortunately, this study is still underway and as a result the report is not public. However, based on their findings to date the total California market size is estimated to be 42,000 units, of which 55%, or roughly 23,000, are within SCE s service territory. 4 Based on the ENERGY STAR list of qualifying products, an estimate of the distribution of sizes was determined. It is estimated that 50% of the units would fall in the medium (25 ft 3 ) range, with 25% in each of the small (10 ft 3 ) and large (40 ft 3 ) ranges. MARKET BARRIERS Hot food holding cabinets are used to maintain food quality and safety, prior to the food being served. Food quality is a subjective barrier and is dependent on the food type; some food may be better preserved at lower temperatures, while others could require higher temperatures. Food safety is governed by the National Science Foundation (NSF)/ American National Standards Institute (ANSI) Standard This standard requires that cooked food be maintained at a minimum of 140 F. However, it does give an allowance that food Southern California Edison Page 3

7 may be kept below 140 F for up to 4 hours, which would likely provide enough time to respond to a DR event without jeopardizing food safety. Given this allowance, the market will likely be confined by food quality constraints. Other barriers that may impact market acceptance rely on understanding the usage profile of the cabinet, (e.g., frequency of openings), and the physical construction, insulated vs. non-insulated. Either factor will impact the ability of the case to maintain temperature, impacting food quality and safety. DEMAND RESPONSE STRATEGIES AND POTENTIAL For the purpose of this evaluation, the DR potential is defined in Equation 1. EQUATION 1. DEMAND RESPONSE POTENTIAL DR potential = (kw reduction /unit) x (Market Size) x (Market Acceptance) STRATEGY 1 UNIT SHUT OFF STRATEGY DESCRIPTION This strategy consists of shutting off the entire hot food holding cabinet during a DR event. This strategy is enabled through communicating technology that receives a signal indicating an event. Additionally, the hot food holding cabinet should have a temperature sensor that determines if the cabinet is operating above the minimum 140 F temperature. Based on the temperature of the holding cabinet, the appliance is able to accept or decline the signal. TECHNICAL DEMAND REDUCTION As this strategy centers on the shut-off of the entire unit, the demand reduction is equivalent to the power draw of the unit. As noted previously, this is dependent on the size of the cabinet, but using the same assumptions the potential is 400 W, 1000 W, and 1600 W, respectively for the small, medium, and large cabinets. MARKET ACCEPTANCE Market acceptance of this strategy is governed by the food quality and safety concerns noted previously. It is highly dependent on the usage of the cabinet and insulation level. Given the fact that the peak period corresponds to the period when restaurants are preparing for the dinner rush, it is assumed that cabinet usage is high, and as a result acceptance is low. Estimates for the market acceptance place it between 1% and 50%. DEMAND RESPONSE POTENTIAL Using Equation 1 the technical demand reduction, market size and breakdown, and various acceptance factors, the DR potential was determined. The results of these calculations are shown in Table 3. Southern California Edison Page 4

8 TABLE 3. DR POTENTIAL: STRATEGY 1 - UNIT SHUT OFF SIZE 1% 5% 10% 20% 50% ACCEPTANCE ACCEPTANCE ACCEPTANCE ACCEPTANCE ACCEPTANCE SCE CA SCE CA SCE CA SCE CA SCE CA Small (10 ft 2 ) Medium (25 ft 2 ) ,750 Large (40 ft 2 ) Total ,825 21,500 STRATEGY 2 USE STAGING TO REDUCE HEATING ELEMENTS STRATEGY DESCRIPTION Similar to strategy 1, this strategy would rely on communicating equipment and a temperature sensor to receive and respond to DR events. Rather than turning the entire unit off, this strategy relies upon the fact that some hot food holding cabinets use more than one heating element. This strategy shuts off one, or more, heating elements to reduce the power drawn by the cabinet. TECHNICAL DEMAND REDUCTION For the purposes of this study, it is assumed that hot food holding cabinets have two evenly-sized heating units. Additionally, it is assumed that each heating element uses ½ the total power drawn by the unit. Based on these assumptions, it is determined that the DR reduction potential ranges from 200 W to 800 W, depending on cabinet size. MARKET ACCEPTANCE Again, the acceptance of this strategy is governed by the need to maintain food quality and safety. However, as this strategy does not completely eliminate the heating capabilities of the cabinet, the acceptance is estimated to be relatively higher. To be consistent with other strategies, a range of 1% to 50% is used for the market acceptance rate. DEMAND RESPONSE POTENTIAL Using Equation 1, the technical demand reduction, market size and breakdown, and various acceptance factors, the DR potential was determined. It is important to note that an assumption is made that only 50% of holding cabinets will have multiple heating elements and subsequently be capable of this strategy. The results of these calculations are shown in Table 4. Southern California Edison Page 5

9 TABLE 4. DR POTENTIAL: STRATEGY 2 - USE STAGING TO REDUCE HEATING ELEMENTS SIZE 1% 5% 10% 20% 50% ACCEPTANCE ACCEPTANCE ACCEPTANCE ACCEPTANCE ACCEPTANCE SCE CA SCE CA SCE CA SCE CA SCE CA Small (10 ft 2 ) Medium (25 ft 2 ) Large (40 ft 2 ) Total RESULTS DR potential for hot food holding cabinets range from 59.1 kw with 1% acceptance when heating elements are staged within SCE service territory to 21.5 MW with 50% acceptance for unit shut off statewide. Table 5 shows the range of total DR potential for the two strategies identified. TABLE 5. RANGE OF DR POTENTIAL STRATEGY 1% ACCEPTANCE 50% ACCEPTANCE SCE CA SCE CA Unit Shut Off ,825 21,500 Use Staging to Reduce Heating Elements RECOMMENDATIONS For both DR strategies identified, the greatest obstacle for implementation is market acceptance. Market acceptance is driven by food quality and safety, and DR strategies need to be designed to not impact either variable. Therefore, it is recommended that additional studies be performed to better understand the impact that these DR strategies would have on temperature and also what temperatures are required for various end-uses (or food types). Additionally, as these strategies have not been demonstrated previously, it is recommended that a demonstration of technical feasibility be performed. Southern California Edison Page 6

10 REFERENCES 1 California Energy Commission California Appliance Energy Efficiency Standards, page Southern California Edison Work Paper WPSCNRCC0003, Insulated Hot Food Holding Cabinets, ( SCE Work Papers part 1.zip ) Personal communication: from David Zabrowski, October 7, NSF/ANSI Standard : Commercial Cooking, Rethermalization and Powered Hot Food Holding and Transportation Equipment. Available for purchase at: Southern California Edison Page 7