Ranges have a unique position in the energy efficiency conversation. As it is, there really is no such thing as an "energy-efficient range," per se. In fact, no Energy Star rating exists for ranges and some states don't offer rebates for this equipment. But with the right specification and maintenance, foodservice operators can achieve energy efficiency and savings with their ranges.
"In this history of the range, nothing has really changed," says David Zabrowski, senior engineer at the PG&E Food Service Technology Center. "In the '90s, one manufacturer had a prototype with great potential based on our testing. Most gas ranges run at 30 percent efficiency, but this one was running at 45 percent efficiency."
What happened to that more efficient range? Cost won out in the end. The more expensive unit didn't have great turndown to begin with, and at a more expensive price point, it was a hard sell, according to Zabrowski. Still, "we're now beginning to see some action in the range category when it comes to energy efficiency," he says.
New Developments in Range Technology
About two years ago, an analyst from outside the industry began examining ranges and found two reasonable solutions: improve the burners or improve the cooking utensil. Enter better burner design and the development of thinner bottom pots.
"Manufacturers are beginning to play around with technologies for looking at the way burners are designed," Zabrowski says. Instead of open burner ports, they're looking into sealed burners for better control over combustion and to optimize the air going to the burner for better heat transfer. This helps slow down the flames so the pot absorbs them more easily.
The idea is that a sealed burner port premixes the gas and air better than before. "Inefficiency comes from too much air being released," Zabrowski says. "That causes the hot air to move past the pot more quickly so the pot has less time to absorb the heat, and the flames go up and out. If the air moves more slowly, the pot has time to absorb all the heat before it's gone."
Also helping to improve the efficiency of ranges is infrared technology. However, Zabrowski says, ranges using infrared technology feature a glass top, which means the buyer needs to evaluate the unit's durability and robustness.
Changes to pilots have also helped improve the efficiency of ranges in the past few years. Some manufacturers now feature spark pilots with essentially a built-in on/off switch to conserve energy overnight or during off-peak hours. For schools, which shut down for months at a time in the summer, this technology can be particularly useful. "These units are more expensive and very application specific," Zabrowski says. "If you're running a 24-hour operation, there is no reason to look into these units. But if you are closed after lunch for the rest of the night it might be worth it. For schools they are definitely worth it."
Problem is, with savings of only about $100 a year for traditional restaurants, depending on the cost of the unit, the investment might not make sense, not yet at least. As the demand for spark pilots improves, that could change. "The criticism for pilot technology is that pilots don't use a lot of energy so the added cost of that feature is currently questionable," Zabrowski says.
Fortunately, an ongoing California Energy Commission project has sought to examine these new technologies to more clearly define the savings potential for ranges, according to Zabrowski. But, because ranges are so behavior dependent, they must be tested in a typical kitchen to draw accurate efficiency scores.
"As it is, thin bottom pots look like they have the potential to save energy because if you heat up the food more quickly, you save energy," Zabrowski says, noting that Oregon offers some rebates for operators purchasing these pots. "But, if you don't shut the burner off, you're still wasting gas." Again, all behavior dependent. Ranges are manually operated, not controlled by a thermostat.
Induction and Electric Ranges
The advancement of induction ranges has been particularly exciting to Zabrowski in recent years. "Some manufacturers are comparing their newest induction ranges with standard electric and gas units and showing considerable energy savings," he says.
By using magnetic coils that react with non-aluminum pots, only a small, initial amount of energy is necessary. It's essentially demand-control technology for ranges. "The range isn't using any electricity if a pot isn't there," Zabrowski says. "Essentially, the pot becomes the heat source. Standard electric speed coil ranges are about 65 percent to 70 percent efficient, whereas induction ranges are 80 percent to 90 percent efficient."
Again, price becomes the issue. "The cost is a lot higher with these units and reliability can be an issue because electronics don't like heat, and kitchens are hot environments," Zabrowski says. While many models maintain fans beneath the surface to cool the units when not in use, we don't have the data yet to see if they can last in a hot kitchen for years on end. In addition, if you buy induction, you also need to buy all non-aluminum pots and pans.
"Where we're seeing induction more is in ground-up projects with new kitchens," Zabrowski continues. "The other place we're seeing more induction is in display cooking." In both cases, he adds, using induction cooking can reduce the strain on ventilation systems, which can help balance out the cost of these pricier units.
Electric ranges, while they save more energy than gas ranges, come under fire — literally — for their difficulty to control. They can take more time to heat up and to respond to changes in cooking temperature needs. Many operators, depending on their location, must use electric, and in some of those locations, electricity is more expensive than gas. At that point, Zabrowski says, "if you're already using electric, then induction is a no-brainer. You get the responsiveness of gas because induction ranges are not slow to heat up and cool down like electric, and you have better performance because the efficiency is better."
Determining the right size range for the operation is critical. How many burners will the operation really use each day? Each hour? It's important to specify the right size range without exceeding the operation's actual needs.
Determining whether a foodservice operation really needs that oven underneath the range is another way to develop a specification that will lead an energy efficient choice. "I've been in tiny restaurant kitchens where they don't have much other than the range with an oven, and they're doing all their baking and roasting right in the range oven," Zabrowski says. "In a lot of those cases you could install a separate convection oven that would work much better."
Maintaining Ranges for Energy Efficiency
The second part of the energy-efficient range story involves proper maintenance, cleaning and care.
Cleanliness is the key to longer lasting, better behaving burners, according to Mark LeBerte, president of ATECH, Inc., in Nashville, Tenn., and winner of FE&S' 2012 Top Achiever-Service Agent award. Unfortunately, many operators neglect to clean their burners.
"Operators should clean up spills when they're done cooking for the day, that's the biggest thing," LeBerte says. "Food spills can block the pilots and the gas."
LeBerte notes that most cast-iron range tops require simply a wire brush to scrub them clean. In really bad cases, it's possible to soak the burners and grates, but not regularly, as cast iron rusts. LeBerte's team will conduct a deeper cleaning during tune-ups and checks, disassembling the different parts and blowing air in to make sure every hole is cleaned out and clear.
Still, it's important to follow the cleaning instructions outlined in the manufacturer's operation manual. "We tell our customers to refer to their user's manual for simple checks and adjustments," he says. "If the manual shows a specific task, the manufacturer wants the operator to do it. If not, a service agent can do it."
Regular preventative maintenance is also key. "We have a check sheet we go through about every quarter with our customers," says LeBerte, noting that most are on a quarterly check-up schedule. That list includes checking to make sure the gas pressure is correct, there are no leaks, and if the burners are running properly, along with checking oven door hinges and gaskets to make sure they're properly sealed and heat is not escaping. Over time, spring-loaded doors will stretch and potentially leak hot air. Thermostat calibration for ranges with ovens is also on that list.
Even with regular maintenance checks and tune-ups, operators need to know what to look for so they can call on service agents in between those regular checks. "That is the first step to recognizing a problem," LeBerte says.
For example, yellow flames can indicate a poorly functioning burner that takes too long to heat up. Blue flames indicate a stronger heat. "You may see two-inch flames and think you have all this power, but if it's all yellow, it's not as hot as you think," he says. Yellow flames indicate a problem with the air shutter and the air and gas mixture needed for efficient cooking. The first step to fix the problem is to clean the burners properly, but if they're clean and flames still aren't blue, time to call a service agent. Service agents can adjust the air-gas mixture by sliding the air shutter left to right on the venturi of the burner to control how much air releases when the shutter valve opens.
For ranges with ovens, operators can set a low cost thermometer on the middle rack to make sure the temperature matches up to the reading on the control panel when set at a test of 350 degrees F for 30 minutes. Otherwise, it's time for calibration.
Other best practices for ovens include not kicking doors shut or throwing them violently open, and certainly not standing on open doors to change hood filters, as LeBerte often sees.
Also, regularly grease burner valves, otherwise they will start leaking. A sign it's time for some greasing is if the valves are difficult or even slightly difficult to turn, or missing completely. "I've seen operators use pliers to turn on burners," LeBerte says.
Electric ranges require less preventative maintenance. Again, cleanliness is key to maintaining cooking efficiency. But another common problem happens when one of the coils in a multiple coil element goes out. "If one is out you might have had a 15kW element and now it's a 10kW element so things are taking longer to heat up," LeBerte says. In some cases, replacing the entire cluster of elements might be necessary versus just replacing one bad element — a common complaint with some electric ranges.