Will an induction cooktop save me energy?
The induction cooktop technology gives a far more efficient transfer of energy than a gas flame or heated electrical element and so boiling a pan of water, for example, is much quicker. This does not necessarily mean that there are great energy savings, but it is more efficeint and can save you time.
Why is it more efficient?
In non technical terms, this would be my explanation: The cooktop itself does not get hot. There is no energy wasted heating up the cooktop and then placing a pan on this hot area for the pan to get hot. Instead the induction field is generated just in the area covered by the pan. The pan itself heats up. Yes there will be some loss of radiant heat from the pan to the surrounding area, but nothing like as much as the wasted heat from a gas ring or electric cooktop heater that is too big for the pan.
There are many statements on the internet about how efficient induction cooktops are. How quickly they boil water. How efficiently they convey energy. What do these statements actually mean? What does it mean for your electricity bill? Your contribution to saving the environment? To summarize: Induction cooktops transfer energy fron the cooktop to the saucepan more efficiently than any other cooktop technology. Year by year you may save a small amount on your energy bill. At the moment, this saving will not offset the additional cost of an induction cooktop. (Much like solar panels. You have the latest, greenest technology. Your electricity bills are lower. But it cost you a lot to get them installed. Don't get me wrong. We all have to do our bit for the environment but, don't confuse short term savings with overall cost reduction.)
So are induction cooktops more efficient?
For the straight scientific answer I turned to a paper prepared for the US Depeartment of Energy, Office of Codes and Standards. I read most of this paper having found it online at US Department of Energy website. The main thrust of the paper is to look at the cost of appliances over their lifetime - so it looks at manufacturing cost, installation cost and running cost. The paper was written some years back (nineteen ninety something) and so reproducing those figures here is irrelevant. What is relevant however is the 'efficiency' of use of energy figures. The paper gives extensive detail on how these figures are calculated. It all seemed good to me. All very objective and scientific. Here is what they came up with. (And rememeber, a higher number is better in this list!)
Gas around 40, electric around 70, induction 84
The study looks at cooktops, conventional ovens, and microwave ovens which are rated using an energy factor. The energy factor (EF) is expressed as a percent and is the ratio of the annual useful cooking energy output of the cooking appliance (energy conveyed to the item being heated) to its total annual energy consumption. The annual energy consumption includes the energy input during the time the load is being heated plus the energy consumed by other features such as a clock, standing pilot, electronic ignition system, or self-cleaning cycles. The DOE test procedure also defines the efficiency of the cooking appliance, and it is important not to confuse it with the energy factor. The efficiency is analogous to a steady-state efficiency as its value is calculated from measurements taken only during the time the load is being heated. From the study we can extract the following key figures:
|Cooktop type||Efficiency||Energy Factor||Annual est. costs, 1990$|
|Electric - baseline||1 to 4||0.74||$18|
|Electric - Halogen||5||0.75||$18|
|Electric - Induction||5||0.84||$16|
|Electric - Radiant||5||0.71||$19|
|Gas - baseline||1 to 2||0.16||$20|
|Gas - electronic ignition||3 to 4||0.40||$8|
|Gas - sealed burner||5||0.42||$7|
|Gas - Reflec surface||5||0.42||$7|
|Gas - Tstat burners||5||0.42||$7|
NB: Costs in 1990$, electric 0.0772$/kWh and gas 5.94$/MMbtu
Source: TECHNICAL SUPPORT DOCUMENT FOR RESIDENTIAL COOKING PRODUCTS, (Docket Number EE-RM-S-97-700), VOLUME 2: POTENTIAL IMPACT OF ALTERNATIVE EFFICIENCY, LEVELS FOR RESIDENTIAL COOKING PRODUCTS, LAWRENCE BERKELEY NATIONAL LABORATORY Prepared for U.S. DEPARTMENT OF ENERGY Office of Codes and Standards
So what do we take away from all of this? At 1990 prices gas cooktops on the whole are cheaper to run. If you are using electric, induction is the hands down winner in terms of cost. Looking at the energy factor induction has the highest (best) score of 0.84 - almost 20% better than any other electric cooktop and twice the score of the nearest gas option.