TINY OFF-GRID HOUSE ENERGY EFFICIENT INDUCTION COOKTOP COOKING
INTRO TO INDUCTION COOKING
This research compares an induction cook top range to an electric cooktop range. Since gas & propane cooktops are not compatible with the air quality & sustainability goals of the Tiny Off-Grid House they were not included.
Natural gas is mainly comprised of >95% Methane. When Methane burns it becomes a catalyst between Oxygen (O2) and Nitrogen (N) creating Nitric Oxide (NO) & Nitrogen Dioxide (NO2); an indoor air pollutant known as Nitrogen Oxide (NOx). NOx is known to cause cardiovascuar and respiratory illneses.
According to the International Journal of Environmental Research, the use of indoor gas stoves, ovens and leaking gas pipes causes indoor air pollution which is attributable to 13% of childhood asthma rates in the United States. Several cities in the U.S. have passed laws banning the use of gas stoves and ovens in all “new” buildings construction: Berkeley, CA, 2019, San Francisco, CA, 2020, New York City, 2021, with several more cities being considered.
A Tiny Off-Grid House kitchen is designed for the home chef with the use of energy efficient electrical appliances. An induction cooktop uses electrical energy most efficiently, cooking food faster & using heat energy more efficiently; subsequently using less electricity. Also, by generating less heat inside the kitchen, less electricity is needed for cooling or venting the kitchen.
A copper coil under the black glass cooktop surface generates a high frequency magnetic field (eddy currents) that heats only the cookware by agitating the iron molecules within the cookware. Subsequently, only the cookware is heated instead of the surrounding surfaces—black glass cooktop or the air. The heated cookware transfers the heat to the food by conduction.
In contrast, an electric stove (Radiant cooktop) relies on heat transfer (conduction) less efficiently through layers of thermal resisters (First the resistance coil is heated, then the ceramic surface and then the mass of the pot). This contributes to a temperature drop as the heat generated in the coils travel through layers of thermal resistance.
STAINLESS STEEL COOKWARE
Photo courtesy of Williams-Sonoma
A discussion of induction cooktops must also include its symbiotic relationship with ferrous (Iron containing) cookware: such as food grade Stainless Steel, Enameled Steel and Cast-Iron. An induction cook top is not compatible with nonferromagnetic cookware; so it will not work with: Aluminum, Copper, Ceramic, Pyrex or Glass cookware.
A high quality stainless steel cookware comes in 3 to 5 alternating layers of Aluminum (AI) sandwiched on top and bottom by stainless steel: Aluminum fast heat conduction ability is balanced by stainless steel slower, retaining, heat conduction ability. Thinner stainless steel pans do not have enough mass to retain heat which may cause the pan to cool when food is added absorbing the heat and subsequently lowering the cooking temperature during the cooking process. Also, thinner stainless steel pans have a propensity to warp when heated. More economical models of stainless steel cookware called “clad bottoms” have a disc of AI or Copper (Cu) on the bottom of the stainless steel cookware. But this may cause food to burn along the edges of the disc seam. High quality stainless steel cookware has a propensity to produce better quality Fond (Pronounced Fahn) brown pieces of burnt food on the bottom of the pan cooking surface which is prized by chefs as an ingredient in pan sauces.
Even stainless steel cookware with an exposed copper bottom is not compatible with an induction cook top. To assess if a cookware is induction compatible simply use a regular magnet; if the magnet sticks to the bottom of the cookware it is induction compatible. Stainless steel cookware does not require seasoning (patina non-stick surface) like cast iron and carbon steel pans. Cast iron and carbon steel pans are also prone to rusting so moisture must be removed from the surface. Reactive metals such as carbon, aluminum, copper & cast iron pots have a propensity to leach metals when exposed to acidic foods, like pasta sauce, causing foods to have a metallic taste. Even nonreactive, food grade 18 -8 (18% Chromium, 8% Nickel), stainless steel cookware is not exempt; prolonged use may gradually release low levels of nickel and chromium which should be a concern for those with allergies or sensitivities to these metals. Exposure to elevated amounts of Nickel is known to cause liver/kidney damage, high blood pressure and lung cancer.
A Stainless Steel pan can easily go from an induction cooktop directly in to an oven for baking skillet pies, cooking thicker meats, roasting whole chicken . . .
HAZARDS OF NON-STICK COOKWARE
Stainless Steel cookware with “non-stick” coating has health concerns unrelated to induction cooking. The “non-stick” layer of PolyteTraFluoroEthylene (PTFE), Dupont trade name Teflon, is a plastic polymer which has the proclivity to chip and become embedded in the food during cooking. Also temperatures of cookware starting at >500° F / 260° C can release toxic fumes known to cause a condition called Teflon Flu or Polymer Fume Fever. Signs and symptoms include, but are not limited to, shortness of breath, fever, nausea . . . The toxic fumes are known avian toxins that can be fatal to companion birds inside the house. The small size of birds make them easily overwhelmed by the toxic fumes. An example are the canaries once used in coal mines to warn miners of poisonous gases emanating from inside the cave. Perfluorooctanoic Acid (PFOA) aka C8, is used in the manufacturing process to help spread the PTFE smoothly on the surface of the cookware. PFOA, along with PTFE, are known carcinogens. The U.S. E.P.A. had asked manufacturers of PFOA to voluntarily remove the toxin from the production of nonstick coating on cookware by 2015.
Aluminum cookware & foilpaper is a neurotoxin, along with Copper, when used to cook food or especially with acidic foods like lemons. Ceramic coated cookware is not durable and can crack or chip releasing lead and cadmium which are toxic to the cardiovascular, reproductive systems, prostrate and bones.
Precision heat control is accomplished using energy efficient touch screen controls and digital LED’s, unlike, an electric cook top analog knobs, used to control the level of the heat. Both controls are maybe comparable, but the induction touch screen control has better precision and more ranges.
Induction cooks food more evenly because the cookware becomes the heating element; not an external flame. Subsequently, this avoids areas of the cookware that maybe hotter or cooler than other areas.
Induction cooking enables rapid heat production of the cookware. Even when the cookware is temporarily removed, then replaced on the cooking zone of the black glass cook top the cooking process rapidly resumes—as long as the auto-off safety feature is not enabled whenever the cookware is elevated off the cooking zone. If the auto-off safety feature is activated sautéing foods may prove to be a challenge. The base perimeter of the cookware should be no more than 1/2” (1.3 cm) beyond the cooking zone. If the cookware is smaller than the cooking zone it will not heat up. Wearing stainless steel jewelry and other ferrous items during induction ion cooking is not a risk because they do not contain a significant amount of iron molecules to activate the cooktop sensor.
INDUCTION COOKTOP IS SAFER
Induction cooking is safer since no flames from a fire is produced. Also, the induction cook top doesn’t get hot, only the cookware. The electricity targets the metal cookware heating the cookware only while keeping the cook top cool. Once the cookware leaves the cooking zone it rapidly cools and the cook top automatically powers off. Cleaning the black glass surface around the heated cookware can be performed while cooking. An induction cook top has the potential to interfere with nearby cardiac pacemakers or similar devices but consult your medical professional for advice. All forms of cooktops should be installed away from the refrigerator since heat sources may interfere with the normal operations of the latter.
The induction cook tops are the easiest to clean. The black glass surface can be easily wiped clean and immediately after cooking without having to wait for the surface to first cool and food to harden. If spills are anticipated during cooking a thin paper towel can be position under the cook ware to catch any spills.
The black glass creates a flat clean surface appearance especially in contrast to some countertops made of stainless steel, marble or cement. The glass surface is susceptible to scratches by sliding cookware along the glass. Electric cook tops give a visual and thermal indicators, that is intrinsic to our visual and tactile senses, when it is ON generating heat. Other than the ON indicator light, an induction cook top black glass surface does not glow when ON. No coils are lighted, no heat emanates from the cooking zone. However, this should not be a concern. As mentioned in the previous two paragraphs: Once the cookware leaves the cooking zone the induction cooktop surface should no longer be hot.
An induction cooktop can have a tendency to generate a low humming while generating heat. This normal operational noise is caused by the magnetic fields. Some additional crackling noises can be generated by low quality cookware that are made of different iron molecules being agitated. Cookware with uneven bottoms or loose fitting handles can create noise from vibrations when heated on an induction cooktop. Cookware and lids constructed with quality, properly attached handles with an evenly balanced flat bottom —no ridges— will prevent vibrations when the cookware iron molecules become agitated. The only other known noise is caused by the fan that may continue to run while the cooktop is powered off to keep the operational controls at a normal temperature.
Ferrous cookware with flat square bottoms are the ideal to create a conductive contact surface. But how do we cook using a Stainless Steel Wok on an induction cook top? Stainless Steel discs can be placed between the induction cooking zone and the Wok or even with a nonferrous cookware; heating the nonferrous cookware by thermal contact.
The number of cooking burners depends on your needs and electrical load. An average meal may use no more than two burners at a time when cooking and the amount of electrical usage would be another consideration to have a conservative number of burners when cooking off-grid.
Achieving good indoor air quality with an induction cooktop is incomplete without proper indoor ventilation. Where possible, a range hood that vents to the outside should be installed directly above an induction cooktop (Especially above gas stoves).
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