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December 2009
ENERGY STAR REPORT

Griddles: Long Road To 'Star Status

By Mike Sherer

One of the most recent foodservice equipment categories added to the Energy Star program also may be the longest in development so far. Griddles were the first type of equipment for which Pacific Gas & Electric Co.'s Food Service Technology Center in San Ramon, Calif., developed a standardized test method more than 20 years ago, but they didn't become an Energy Star category until this May.

Back in 1987, PG&E helped fund and open the FSTC to benchmark the energy performance of commercial kitchen equipment. Recognizing that a preponderance of operations used griddles, folks at both FSTC and PG&E figured that was as good a place to start as any. Some data were already available on the category, since Southern California Gas & Electric had developed a test method to determine energy performance of gas griddles for the American Gas Association.

But FSTC co-founder Don Fisher and PG&E's Dan Kaufman wanted to take it a step further and measure both energy efficiency and production capacity, or throughput, under actual cooking conditions. Further, they wanted to simulate high-volume, medium-volume and light-duty production.

"It was as much of a learning curve for us as anyone else," says David Zabrowski, FSTC's director of engineering, who says the initial effort predates his tenure there. "There were so many variables to consider, and a uniform testing procedure had to address them all."

First Challenge: Accurate Temperature Read
An accurate temperature reading of a griddle's cooking surface was the first challenge. Infrared temperature sensors didn't provide a true indicator of griddle-surface temp, so the team welded surface probes directly to the griddle top. Using a grid pattern of probes, the team mapped average temperatures across the entire surface of the test griddles. Affixing probes directly over the thermostats enabled them to adjust the temperature settings so they could achieve a set surface temperature to measure idle-energy rate.

By using these sorts of test criteria, testers hoped to get as uniform a temperature across the griddle surface as possible. What they discovered, though, was a much bigger discrepancy in surface temperatures than the 5°F that several manufacturers claimed their griddles would maintain. The lowest difference between hot and cold spots was 37°F, the highest an amazing 91°F.

Coming up with a consistent product to cook was another challenge. To come as close to real-world production as possible, the team chose hamburgers, but quickly realized that moisture content, fat content, grind, patty thickness and initial temperature of a hamburger patty all would affect how long it took to
cook.

Variables To Consider
Testers considered a synthetic burger product made with soy protein, but decided producing it entailed just as many variables. They stuck with ground beef patties and developed specs for burgers that would meet uniform testing procedures. To determine how long to cook the product, FSTC identified the correlation between the internal cooked-product temperature and the weight loss after cooking. With those specifics nailed down, FSTC was able to decrease the variation in results from different batches.

Another variable that cropped up during testing was the effect ventilation might have on idle performance. The team took a look at idle-energy use of the four test griddles while running the hood fan at different speeds. Sure enough, one of the griddles used measurably more energy when the hood's ventilation fan was cranked up high. So, the team set test specifications for the vent hood, too. Other variables FSTC considered and addressed in the test specification included things like the heating value of the gas to determine the actual quantity of energy used in a test.

By '89, the team had published its uniform testing procedures for gas and electric griddles, and in '90, the procedures were approved by ASTM Int'l. as an industry standard. Since then, the test procedures have been revised twice, in '95 and '99, to improve and update them, but it took another 10 years to include the category in the Energy Star program.

"Nobody did anything in the category until AccuTemp submitted a griddle for testing about 10 years later," Zabrowski says. "Manufacturers' R&D departments focused on other equipment. Griddles were really considered a commodity item. Denny's asked us to performance-test griddles several years ago, which was the first time we really tested a range across the category from low end to high.

"In 2005, the California Energy Commission wanted to push an appliance-rebate program for energy-efficient equipment, and we tested even more products. By then we felt we had built a solid database which at least had a good range of griddles from low to high efficiency, so we went to Energy Star and suggested they consider the category."

Why did it still take so long for Energy Star to approve and release the specs?

"As long as a test method is voluntary it's okay," Zabrowski says. "But when the Environmental Protection Agency gets involved, everyone looks at it more seriously and evaluates it more thoroughly. The discussions over both the methodology and where the bar should be set stretch out the comment periods. And to be fair, Energy Star doesn't have unlimited resources, and their people were working on convection ovens at the same time."

Compared To What?
To be qualified as an Energy Star griddle, gas equipment must have cooking-energy efficiency = 38% and a normalized idle energy rate = 2,650 Btu/hr. per sq. ft. of surface area.

For electric griddles, the standard is cooking-energy efficiency = 70% and a normalized idle energy rate = 355 watts per sq. ft. Those efficiency rates apply when the griddle is cooking heavy loads per the ASTM Int'l. F1275 and F1605 standards.

What's it all mean? Energy Star says, in round terms, its qualified griddles are about 10% more efficient than standard griddles. (That figure can be conservative, though: Qualified gas units' 38% actual cooking efficiency, compared to 32% for typical units, is a 19% improvement during actual cooking.)

Energy Star-qualified electric griddles can save businesses about 2,270kWh annually, or an average of $190/year on utility bills. Energy Star gas griddles can save 15 MBtu annually, or an average of $175/year on gas bills.

Visit www.energystar.gov/index.cfm?c=griddles.pr_comm_griddles to find a list of qualified models.

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