Commercial kitchens—such as those found in full-service and quick-service restaurants, hotels, and hospitals—are intense energy users, consuming as much as three times more energy per square foot than most other types of commercial buildings. Because energy costs for these facilities typically account for between 25 and 30 percent of total operating expenses, upgrading equipment to be more energy efficient can increase your bottom line while also providing significant non-energy benefits including improved operating performance, more-uniform cooking, and increased kitchen staff comfort.
Although some of the upgrades described here are simple and relatively inexpensive, others can involve significant upfront costs and require extensive implementation efforts. Ask your utility for more information before initiating such projects.
What are the options?
Many technologies in commercial kitchens use energy—from food preparation equipment such as ovens and boilers to operational essentials like ventilation and water heating—and almost all of them can be made to operate more efficiently. Although efficient equipment may have higher up-front costs, the energy savings it yields often produces short simple payback periods, making such upgrades economically justifiable in a wide range of circumstances.
Kitchen equipment such as ovens, fryers, broilers, and burners all require energy to function. By purchasing energy-efficient equipment in new construction or when existing equipment fails, facilities managers can significantly reduce energy use in the kitchen.
Purchase high-efficiency equipment Substantial energy savings are achievable by replacing conventional equipment (Table 1) with Energy Star–qualified products, which are often 15 to 30 percent more energy efficient than standard equipment, or other high-efficiency equipment if Energy Star specifications don’t exist. In the latter case, contact the Pacific Gas and Electric Co. Food Service Technology Center for a list of high-efficiency equipment models. In general, because of the capital investment required, the best time to install a new, more-efficient model is at the end of your existing equipment’s usable life. Steam cookers are a notable exception to this rule; they often yield large enough energy savings to warrant early replacement.
Use Turbo Pots Almost every food service establishment in the U.S. has at least one gas-fired range used to maintain a stock pot full of simmering water for various cooking uses as well as for heating up and cooking food. Turbo Pots incorporate metal fins into the bases of standard restaurant-quality cooking pots to improve convective and conductive heat transfer into the pot, thereby boosting cooking efficiency. An upgrade as simple as a new set of stock pots could mean a 50 to 60 percent decrease in the energy consumption of open-flame gas-range cooking—which equates to a simple payback period of about eight months. At present, these types of pots are only produced by cooking manufacturer Eneron.
Although ventilation is vital for maintaining air quality and mitigating smoke in the kitchen, it also uses a large amount of energy. Because a 50 percent reduction in fan speed can reduce fan energy consumption by as much as 80 percent, equipment that minimizes fan speed when possible can yield large energy savings.
Specify effective exhaust hoods Hood style has an impact on energy use because it affects the design exhaust rate. The proximity-style (backshelf) hood requires the least exhaust air and is therefore the most efficient, followed by the wall-mounted canopy hood and single-island canopy hood, respectively. To reduce the exhaust rate for any hood, install end panels and specify hoods that have a lip along the leading edge. Also, choose Underwriters Laboratory–listed hoods because they typically require lower exhaust flows than unlisted hoods. Group heavy-duty appliances, such as charbroilers and ranges, under the center of the hood, and place ovens at the ends. Push appliances as far back under the hood as possible. For any type of hood, turning it off at night may save energy.
Use variable-speed hood controllers Intelligent, variable-speed hood controller systems can significantly reduce energy costs in commercial kitchens. Standard kitchen exhaust hoods use single-speed fans and are left running at full speed throughout the kitchen’s operating hours, even during idle periods. A variable-speed hood controller uses a photoelectric smoke or heat detector to determine when and how much ventilation is needed and activates the exhaust fan at the proper speed. Given the large energy savings possible, this technology can yield simple payback periods as short as one to two years.
Introduce makeup air effectively Depending on the layout of the space, an effective method for reducing the energy costs associated with kitchen makeup air may be to pull makeup air from the dining room into the kitchen. That air must be supplied by the HVAC system to meet code requirements for ventilating the dining room. Using it in the kitchen as well reduces the total amount of makeup air required, thereby decreasing the fan power needed and the amount of air that must be conditioned.
When makeup air is introduced directly into the kitchen, discharging it downward starting from a low position on the wall behind the cooking appliances will cause the least disturbance in the exhaust system’s ability to capture and contain effluents. For makeup air introduction from the ceiling, use perforated plate diffusers and keep makeup air delivered near the hood at low velocity. Energy-efficient choices for makeup air conditioning include evaporative cooling and direct-fired heaters.
Refrigerators, freezers, and ice makers are widespread in many commercial kitchens and typically represent a significant source of energy consumption.
Install evaporative fan controllers In almost all walk-in coolers and freezers, whether small or large, air is cooled by forced circulation evaporators that contain propeller fans powered by fractional-horsepower motors. Typically, these fans run continuously even though, on average, full airflow is required only about half the time. Controllers are available that slow these fans when full-speed operation is unnecessary, saving 10 to 60 percent of overall refrigeration energy. Users report paybacks as short as one year.
Use efficient fan motors For new walk-in refrigerators or freezers or those with failing fan motors, install or specify high-efficiency motors. A high-efficiency motor in a walk-in will do exactly the same work as a standard-efficiency evaporator fan motor, yet the annual cost savings per motor can result in about a one-year payback for the total cost.
Purchase Energy Star solid-door refrigerators and freezers Energy Star–labeled commercial solid-door refrigerators and freezers can reduce energy consumption by as much as 45 percent, so purchasers can expect to save $170 per refrigerator and $120 per freezer annually (at an electricity rate of $0.087 per kilowatt-hour). This results in a 1.0- to 1.2-year simple payback of the initial additional cost.
Install efficient ice makers When purchasing a new ice maker, consider both the capacity you actually need and the rated efficiency of the unit. A high-efficiency air-cooled commercial ice maker with a capacity of 1,200 pounds (544 kilograms) of ice per day can yield savings of up to $370 when compared with a standard unit.
Commercial kitchen staff have to do a lot of cleaning, and hot water—and therefore water heating—is an essential element of getting it done. By choosing equipment that uses less water, facilities managers can save money on both energy and water bills.
Purchase a high-efficiency dishwasher High-efficiency dishwashers are distinguished by their low water consumption per rack for conveyer or door-type dishwashers (this may not apply to under-counter units). NSF, a nonprofit that develops health standards, rates equipment for efficiency and consumption; this information is available on its website. Purchasing or renting a dishwasher with an NSF water consumption rating of less than 1 gallon per rack reduces both the amount of water used and the amount of water heating necessary.
Low-temperature dishwashers use less energy than high-temperature units, but operating costs are about the same because of the cost of the sanitization chemicals required for low-temperature units. If you choose a high-temperature dishwasher, consider installing a gas booster heater rather than an electric one—depending on local energy prices, energy cost savings often more than make up for the increased capital and installation cost.
What’s on the horizon?
Until recently, manufacturers have been reluctant to redesign food service equipment to improve efficiency, citing a concern that food taste and appearance could be negatively affected. However, food service operators are becoming more concerned with energy costs and are also seeing efficiency as a cost-effective way to participate in the trend toward green restaurants. These drivers are encouraging manufacturers to develop a variety of new products designed to cut energy use while also yielding improved performance, and many of these products are poised to enter the market.
One such product is the Advanced Underfired Charbroiler, developed by the Gas Technology Institute and funded by the California Energy Commission’s Public Interest Energy Research (PIER) program. Unlike most charbroilers, this unit incorporates a hood to lower cooking heat loss, minimize the heat burden to the space, and reduce grill warm-up time. A built-in temperature probe and thermostat control modulate the burners, maintain cooking setpoint, and reduce idle energy usage. Significant energy reductions are achieved by lowering the hood and cycling the burners off during idle periods, while maintaining the grill surface temperature required to impart grill marks and charbroiled flavor. When the performance of the prototype design was tested, researchers measured cooking energy efficiencies of 45 percent with the hood open and 52 percent with the hood closed—improvements of 50 percent over standard charbroiler efficiency.
Another promising product, also developed through the PIER program, is the Rocket Fryer. By incorporating an innovative heat exchanger with an oil-pumping system that uses recovered heat from the flue gas to heat the oil as it’s circulated through the system, this fryer yields efficiencies that are 16 percent higher than the minimum Energy Star criteria. In addition, it provides a lower average frying-oil temperature, eliminates hot spots that can lead to less-uniform frying, and uses one-third less oil than a standard fryer while maintaining typical fryer production capacity. Consumers and some health departments are now advocating for the use of healthier but more expensive non–trans fat oils for frying; by reducing the amount of oil required, the Rocket Fryer offers food service operators oil cost savings as well as energy savings.
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