Conservation in Commercial Kitchen Design

By Susan R. Ecker

Rumsey Engineers Inc.

Water is essential to human life, and, while two-thirds of our planet is covered with water, the supply of fresh, potable water is very limited. It is crucial that water use be as efficient as possible so that there is an adequate supply of this vital resource. There are many appliances that utilize water in a commercial kitchen. This article will examine some of the most water intensive processes and discuss ways that a food service operation can be water efficient.

Steamers

Traditional steamers are water-intensive appliances, incorporating a separate boiler or steam generator to produce steam for the cooking compartment. "Connectionless" steamers generate steam in a reservoir at the bottom of the cooking compartment, and water is added and drained manually at the beginning and end of the day. Condensed steam simply returns to the reservoir instead of draining outside the compartment. Since there is no continuous flow out the drain, these steamers do not require condensate cooling water. A typical 6-pan "connectionless" steamer consumes 1 to 2 gallons per hour (gph), as compared to 30 - 40 gph for a traditional steamer, while operating at peak capacity. Replacing a boiler-style steamer with an equivalent sized connectionless steamer could save 174,500 gallons of water per year.

Estimated total water savings = 174,500 gallons per year

Combination ovens

The original combination ovens were ovens and steamers in the same box. These combination ovens incorporated a separate boiler or steam generator to maintain humidity in the cooking compartment and required a continuous stream of cooling water to lower the temperature of water exiting the cooking cavity before it reached the drain.

Combination ovens offer multiple cooking modes, including dry heat, moist heat and steam. Boilerless combination ovens generate humidity by spraying a fine mist of water on the heat exchangers at regular intervals. The mist is quickly flashed into steam and circulated throughout the cooking cavity. This design requires less water to maintain humidity in the cooking environment and, subsequently, less cooling water. A 10-pan boilerless combination oven consumes 10 - 15 gph, as compared to 30 - 40 gph for a traditional combination oven, while operating at the highest humidity level and would save 110,000 gallons per year over a boiler-style combination oven.

Estimated total water savings = 110,000 gallons per year

Pre-rinse spray valves

Pre-rinse spray valves are used to wash food particles off dirty dishes before running the dishes through a dishwashing machine. Most of the valves on these sprayers are designed to spray water at 2.5 gallons per minute (gpm) to 5.0 gpm. To save water in a dishroom, replace the high-flow pre-rinse spray valve with a low-flow unit, defined as 1.6 gpm or less. If the dishwasher is pre-rinsing dishes for three hours a day, and if the 2.6 gpm valve is replaced with a 1.6 gpm valve, daily water consumption will drop from about 470 gallons per day (gpd) to 290 gpd, saving about 66,000 gallons of water a year.

Water from a properly designed low-flow spray valve hits the dirty plate with a higher velocity than the velocity produced by a high-flow valve. With a low-flow spray, cleaning performance can be as good or better than with the high-flow units. This means that water savings will not impact dishroom productivity.

Estimated total water savings = 66,000 gallons per year

Dishwashing machines

Dishwashing machines use large volumes of water during the course of operation. Chemical-sanitizing machines are known as "low temp" machines, and those using hot water for sanitizing are known as "high temp" (180 F) machines. Dishwashing machines have a wide range of water consumption, but a typical food service operation serving 300 meals per day, using a door-type machine, could expect the appliance to consume 600 gpd. A larger operation, serving up to 600 meals per day and using a conveyor type dish machine, could expect the water consumption to be 1000 gpd. Proper selection, operation and maintenance of the dishwasher are important in minimizing water use.

Dishwashers that use less than one gallon of water per rinse cycle should be specified. A door-type dishwashing machine consuming 1.5 gallons per rinse cycle would consume 164,250 gallons per year. A machine consuming 1.0 gallons per rinse cycle would consume 108,000 gallons annually, saving 56,250 gallons of water. When comparing dishwashers, even a small difference in rinse cycle water consumption equals significant water savings. Dishwashing machine per-rack water consumption data can be found in the NSF International listings (www.nsf.org/Certified/ResAppliances).

Estimated total water savings = 56,250 gallons per year

Waste disposal systems

Garbage disposers consume between 5 and 8 gpm during operation, while pulpers and scrap collector systems consume 2 gpm of water during operation. Garbage disposers have recently undergone scrutiny in various areas due to tighter restrictions on dumping solid waste into sewer systems. Scrap collector systems accumulate solid waste in a centralized bin that can be emptied into the garbage. A typical disposer could consume anywhere between 400 and 1800 gpd, depending on whether it employs a flow control.

Scrappers are an alternative to pre-rinse stations. These devices employ a high flow of recirculated hot water to rinse dishes before loading into a dishwasher. These systems typically consume 7 gpm of water during operation. Typical daily consumption for these units ranges between 1,600 and 2,500 gallons. Scrap collectors consume substantially less water than standard scrapper systems. A typical scrap collector would consume 500 -700 gpd. A scrap collector would be a better choice for a waste disposal system.

Estimated total water savings = 328,500 gallons per year

Dipper wells

Dipper wells are used as utensil rinse-and-hold stations on the front line. Most have a single spigot and valve, and they may use either cold or hot water. Typically, the dipper well valve is turned to full flow and never turned off during serving hours. Because dipper wells are small, many operators don't think they have much impact on water consumption. At a typical flow rate of 0.5 gpm, and a 16-hour operating day, a dipper well will use 175,000 gallons a year.

In order to conserve water, turn the dipper well off when it is not in use. Turning it down during the operating day or completely replacing the valve with one rated at a lower flowrate are two more ways to save water.

Estimated total water savings = 43,750 gallons per year

Conclusion

The commercial kitchens of yesterday wasted large quantities of water. Due to the possibility of drought in many parts of the country, water is becoming a valued commodity. As such, water conservation is becoming an integral part of commercial kitchen design. Commercial kitchens can use less water with the same amount of meals produced and while maintaining the required quality.

If the equipment noted above were to be installed as part of a commercial kitchen design, approximately 779,000 gallons of water would be saved per year, as compared to more traditional kitchen equipment. In addition to water savings, the cost of water and sewage charges would be saved, thus improving the bottom line while helping conserve this most precious of resources.

References: www.energystar.gov, www.nsf.org