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Induction cooktops respond quickly, avoid gas combustion, are tops in energy efficiency, and limit risk of burns.

Our induction cooktop blends in well with our matt-black Richlite countertop. Click to enlarge.
Photo Credit: Alex Wilson

One of our early decisions in the planning for our farmhouse renovation/re-build was to avoid any fossil fuels. If the State of Vermont can have a goal to shift 90% of our energy consumption to renewable sources by 2050, we want be able to demonstrate 100% renewables for our house today.

That decision meant using electricity, rather than propane, for cooking. Electric cooking was actually a very easy decision for us. When our daughters were very young, roughly 25 years ago, my wife and I replaced our gas range with a smooth-top electric range. I had read too many articles about health risks of open combustion in houses; I didn’t want to expose our children to those combustion products.

And I knew that even the best outside-venting range hoods don’t remove all of the combustion products generated when cooking with gas.

Deciding on induction

We were surprised back in the late ’80s how quickly we adjusted to an electric cooktop. It’s not as controllable as gas, but we made due just fine for 25 years. Nonetheless, friends always complained about electric cooktops being too slow or not controllable enough, so we wanted to try out the electric option that top chefs are increasingly turning to: induction.

Controls are very easy, though all electronic. I'm hoping they'll hold up.
Photo Credit: Alex Wilson

For our new house we bought a KitchenAid induction cooktop for our kitchen island. I had wanted to go with the technology leader, Miele, but at about $2,500 for Miele’s 30-inch model, the cost was just too high for our budget. Even the less-expensive KitchenAid version stretched our budget considerably.

What is induction?

Electromagnetic induction, which was discovered in the early 1800s by Michael Faraday, is the process in which a circuit with alternating current (AC) flowing through it induces current in a material placed nearby. It is key to the functioning of induction (asynchronous) motors and most electric generators.

In the case of induction cooking, there’s an electric coil under the glass surface of the cooktop through which AC electricity flows. This current, in turn, generates current in a ferrous metal (iron or steel) pan that’s very close to it (separated by the glass cooktop). Electromagnetic current flows through the bottom of the pan, but because iron and steel aren’t very good electrical conductors, that electric current is converted into heat—more specifically, into electric resistance heat, since the material resists the flow of electric current.

Because the stovetop surface doesn't heat up, induction cooktops are much safer than any other type. This pan of water boiled with no impact to the newspaper.
Photo Credit: Alex Wilson

The result is that the pan or skillet heats up and transfers that heat to whatever is being cooked. So, in effect, the pan becomes the heat source.

If you have a rice cooker, you’re probably already using induction cooking, since that’s how most rice cookers work.

This is different than conventional electric cooktops in which the cooktop itself is heated by electric resistance, and the heat is transferred to the cooking pot. Again, with induction heating, the cooktop only has electricity running through it as it induces heating in the pot.

Advantages of induction cooking

Speed and controllability. Because the pan generates the heat directly, induction cooking is very fast—heating up immediately when turned on and cooling down immediately when the current is reduced or turned off. Heat output can be adjusted even more quickly than with gas burners.

Energy efficiency. Induction cooktops are the most efficient of any option in transferring heat generated by the stove to a pot or pan. According to a study done by Lawrence Berkeley National Laboratory for the U.S. Department of Energy, gas cooktops are about 40% efficient, electric-coil and standard smooth-top electric cooktops are 74% efficient, and induction cooktops are 84% efficient (see Table 1.7, page 1–22). Before you get all excited, though, be aware that cooking accounts for less than 3% of average household energy consumption—so don’t expect an attractive payback for the extra cost of an induction cooktop!

Only ferrous metal pans work on induction cooktops—such as cast iron and stainless steel that a magnet sticks to the bottom of.
Photo Credit: Alex Wilson

Less waste heat. Another aspect of that energy efficiency is greater summertime comfort. We’ve only been in our house for a couple months so haven’t used it in hot weather (that’s for sure!), but a friend who has an induction cooktop raves about the summertime benefit of not heating up his kitchen as much as he used to with a gas cooktop.

Safety. Induction cooktops, like other electric cooking elements, avoid combustion and gas lines, so are inherently safer than gas burners. But induction cooktops go further, dropping a piece of paper on a cooktop that’s on can’t cause a fire. In fact, as shown in the photo, you can cook with a piece of paper between the cooktop and the pot (although doing so probably isn’t a good idea). The electromagnetic induction happens through the paper.

Drawbacks of induction cooktops

Ferrous metal cooking vessels required. Aluminum, copper, and some stainless steel cookware won’t work, so buyers of induction cooktops may have to invest in new pots and pans. Use a magnet; if it sticks to the bottom of the pot, it will work on an induction cooktop. Fortunately, there are lots of options, including plenty that are reasonably affordable.

High cost. While the cost of induction cooktops has dropped in the last few years, they are still pricey. We spent $1,400 on our 30-inch KitchenAid Architect Series II induction cooktop, and the list price of that model is $1,849. A comparable KitchenAid standard electric cooktop (non-induction) lists for $1,299. The high cost of induction today is partly because of the induction technology, and partly because induction is only available in the high-end product lines from appliance manufacturers. The cost should come down and induction gains popularity and spreads into lower-priced product lines.

Health concerns? There is some concern that the electromagnetic fields (EMFs) created by induction cooktops could be hazardous. I understand that the field drops off (attenuates) very quickly with distance from the cooktop, though I haven’t borrowed a gauss meter to actually measure EMFs from our cooktop. I haven’t read credible reports of health problems from induction cooking, but I couldn't rule it out.

Our cabinets were made by Greg Goodman of Brattleboro using native sugar maple along with Columbia Forest Products' formaldehyde-free PureBond hardwood plywood.
Photo Credit: Alex Wilson

Bottom line

I like our induction cooktop a lot. I’ve only had one frustrating experience: the time last month when I set out to make a big batch of chili for an office gathering and discovered that the largest of the skillets in our cookware set doesn’t work with induction elements, even though all the others do. I’m assuming that because the diameter of that pan is so large, the manufacturer used a disk of aluminum or copper, rather than steel, to conduct the heat to the edges more evenly.

Overall, my wife and I are very pleased with induction, though it does take some getting used to. We got a rimless model, and the black ceramic-glass surface blends in quite well with the black Richlite countertop material.

Alex is founder of BuildingGreen, Inc. and executive editor of Environmental Building News. In 2012 he founded the Resilient Design Institute. To keep up with Alex’s latest articles and musings, you can sign up for his Twitter feed.

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Comments

1 electricity draw posted by Tristan Roberts on 03/17/2014 at 10:16 pm

Alex, how many watts does the cooktop draw when it's on at full tilt? Partial? Any idea how many kilowatt-hours you consume through it on a daily basis?

2 Wattage of my induction cooktop posted by Alex Wilson on 03/17/2014 at 10:59 pm

Unfortunately, I don't have a fourth eMonitor circuit for 220-volt loads, so I'm not currently collecting that information. I'm hoping to figure out a way to add a few circuits for data collection.

3 induction can change how you think about design posted by Lloyd Alter on 03/27/2014 at 05:19 pm

My former boss Graham Hill, who built a high end tiny apartment after he left TreeHugger, used induction in an interesting way: since they use so little power and are so cool, he has three plug-in units that he keeps in a drawer and takes out as needed. Most of the time he needs only one; for dinner (who cooks in Manhattan) he might use two. being cool and portable has some big space-saving advantages. http://www.treehugger.com/slideshows/interior-design/visiting-graham-hills-amazing-lifeedited-apartment/page/8/#slide-top


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