Power Kitchen: Energy-Efficient Cooking Equipment

key_points
  • Significant savings can be found in ENERGY STAR-qualified appliances.
  • The Fisher-Nickel Food Service Technology Center (FSTC) offers life cycle cost calculators for various cooking equipment.
  • The use of hot-food-holding cabinets is another cooking technique that can reduce overall energy use.

Electric cooking appliances are generally very efficient, though the following suggestions may help to further reduce energy costs.

  • Upgrade equipment or change operating procedures to reduce energy costs. Significant savings can be found in ENERGY STAR-qualified appliances.
  • Under part-load operation, electric fryers and griddles have proven more energy efficient than gas fryers and griddles. Under idle conditions, the energy consumed by a gas unit may exceed that of an electric unit by a factor of three or more.
  • Use TRIAC controls for regulation of energy. The TRIAC is a three-terminal device that controls and conducts current flow to ensure that the proper amount of power is being used.
  • Flat ribbon, low-watt-density heating elements consume less energy and have longer lives than traditional round calrod heating elements.
  • Add insulation or upgrade insulation for electric units. Improved compartment insulation on steamers and kettles reduces heat loss to the kitchen and standby energy consumption.
  • Incorporate demand ventilation, which modulates the range hood and makeup air fan speeds using infrared sensors and variable speed motors. A case study has shown a 60% decrease in demand (kW) and energy (kWh) consumption, as well as an equivalent savings in heating of outdoor makeup air using this technology.
  • Use energy-efficient exhaust hoods that use outside air rather than inside conditioned air for ventilation.
  • Side curtains around cooking equipment can help restrict the flow of conditioned air to the outside.

An ENERGY-STAR-qualified electric open-deep fat fryer must meet a minimum cooking efficiency of 80%, and also meet a maximum idle energy rate of 1,000 watts. In addition to shorter cooking times, a commercial restaurant may be able to increase production throughput with more energy-efficient appliances. The user may also want to consider frypot insulation to further reduce standby losses and to lower the idle energy rate. The Fisher-Nickel Food Service Technology Center (FSTC) offers life cycle cost calculators, including one for electric fryers.

The use of hot-food-holding cabinets is another cooking technique that can reduce overall energy use. An ENERGY STAR unit must meet a maximum idle energy rate of 40 watts/cubic foot, and is generally 50% to 60% more energy efficient than standard models. Models that meet this requirement incorporate better insulation, which reduces heat loss, and may also offer additional energy-saving devices such as magnetic door gaskets, auto-door closures, or dutch doors. The insulation of the cabinet also offers better temperature uniformity within the cabinet from top to bottom. FSTC’s hot-food-holding cabinet cost calculator provides a means to compare various designs.

Electric steam cookers can also achieve ENERGY STAR ratings if they meet a minimum cooking efficiency of 50% while also meeting maximum idle energy rates. Idle energy rates are specified for 3-, 4-, 5-, and 6-pan sizes. These more efficient units use considerably less water (in some cases almost 90% less—from 25 gallons per hour down to 3 gallons per hour for the top rated units). This lower water use can add up in a busy commercial cooking establishment, and will also lower the facility’s water utility bills. The FSTC offers an electric steamer life cycle cost calculator on its Web site.

A commercial kitchen will also include refrigeration equipment. Where possible, the end user should select the more energy-efficient solid door, as well as reach-in refrigerators and freezers that are designed with components such as Electronically Commutated Motor (ECM) evaporator and condenser fan motors, hot gas anti-sweat heaters, or high-efficiency compressors, all of which will significantly reduce energy consumption and utility bills. Compared to standard models, ENERGY-STAR-labeled commercial solid door refrigerators and freezers can be 40% to 50% more energy efficient compared to standard models. FSTC also provides a helpful cost calculator on refrigerators so that the restaurant owners can do their own analysis.

Comparison of Energy Consumption for Gas & Electric Cooking Appliances
GasElectric
CapacityOperating Hours per Day (h/d)Duty Cycle (%)Annual Energy (kBtu)Duty Cycle (%)Annual Energy (kBtu)Annual Energy (kWh)
Fryers
Open Deep Fat35-50 lb1220%74,90020%38,30011,200
Pressure/Kettle30-50 lb1030%56,60033%21,3006,200
Flat Bottom – Chicken/Fish125 lb.1030%168,00020%53,20015,600
Flat Bottom – Donut80 lb820%34,90014%17,0004,985
Griddles
Single-sided3-foot1234%>86,10024%38,30011,232
Broilers
Underfired3-foot880%210,00070%85,20024,960
Overfired3-foot870%115,00070%74,50021,840
Ranges
Range Top6 Burner1220%120,00025%38,30011,200
Range Oven840%39,90025%17,0004,990
Chinese Range2 Wok1030%187,000
Ovens
Standard38 X 38835%62,40025%42,60012,500
Deck1030%65,50020%21,3006,240
Conveyor1050%212,00050%213,00062,400
Rotisserie860%74,90065%42,60012,500
Steamers (boiler*)
Pressure*6 Pan1415%140,00012%74,50021,800
Pressureless*6 Pan1415%140,00020%74,50021,800
Connectionless6 Pan1414%37,30010,920
Kettles, Steam60 Gal.440%62,40040%34,0009,980
Braising Pan30 Gal.445%49,90060%29,8008,730
Source: Commercial Kitchen Appliance Technology Assessment, Food Service Technology Center, 2002