Energy v cost, do people really not know the difference?

[ericmark]

I have just read an article about saving energy.

Numerous households might not realise that various home gadgets can quietly drain modest amounts of electricity, accumulating costs on your energy bill over time.

Whilst they're not the primary culprits behind enormous electricity bills, switching them off represents a crucial tactic for energy conservation in every household.

and it lists things which switching them off does not really save energy, as in the main, electric used becomes heat, and so ones thermostat just adjusts how much energy is used for direct heating, so swings and roundabouts, no real energy lost.

However, since electric costs more than gas or oil in the main, there may well be a cost saving using oil or gas instead of electric, if one has the option.

Be it a gaming console, satellite TV box, old fridge, microwave oven, or desk top computer, there will be good and bad, but they are not in general high power users, just some, I tested a Sky+ box, and a free to air box, both satellite TV boxes, the Sky+ used around 15 watt on stand-by, the free to air so low I could not measure it with plug in tester.

The Microwave on stand-by uses so little, and I remember the problems when someone from social services told my mother to turn off the oven at the wall, and then she could not get it to work, as the clock needed setting first, the problems caused by general statements are massive. I have used a plug in tester, and yes there were some surprises, but in both directions.

I have looked at air fryer v microwave, and since the air fryer turns on/off and the microwave is going all the time, air fryer may be cheaper to run, but it depends on what is being cooked.

I was told vented tumble driers cost more to run than condenser type, but that is incorrect, as the vented can often be run at a lower setting, so 90 minutes at 1 kW cost less than 60 minutes at 2 kW. Vented only cost more if used on high setting.

Got the same with using an immersion heater compared to central heating boiler, the immersion heater uses far less energy, but it may cost more, but the operative word is "may", these reports never seem to say "If you don't have off-peak" or any other factor which could change the results.

So how much energy is used to save energy?

 

[JohnW2]

I have looked at air fryer v microwave, and since the air fryer turns on/off and the microwave is going all the time, air fryer may be cheaper to run, but it depends on what is being cooked.

A microwave only 'goes all the time' if it is set to "100%", otherwise the on/off duty cycle is varied.

However, by virtue of the nature of its operation, a microwave oven predominant;y heats the food (water within the food, actually) whereas an oven/air fryer will heat up the appliance to an appreciably greater extent. Furthermore, microwave cooking is generally much quicker, leading lower heat losses to the surrounding environment (which, at least in Summer, represents 'wasted energy'). For those reasons, I would expect a microwave to be appreciably more 'efficient' (higher proportion of energy used getting into (and 'cooking') the food).

 

[Harry Bloomfield]

For those reasons, I would expect a microwave to be appreciably more 'efficient' (higher proportion of energy used getting into (and 'cooking') the food).

There was a piece on TV, this morning, which suggested that the on all the time clock display, of a microwave oven, actually costs more per day, to run, than actual cooking in the oven. Our microwave, tends to get perhaps 4 minutes per day of use, on full power.

Gas heated, gas hot water, our big electric consumers are the fridges, followed by TV, with a base load of around 60w.

 

[ericmark]

The microwave is vented, and heat is lost all the time it is running, the air fryer recirculates the hot air. It will depend on the food being cooked, clearly can't use an air fryer to re-heat coffee. And microwave chips are not much good. But in general, the air fryer uses less energy.

But not the way my wife uses it. The basket is sculptured to circulate the air around the food, similar to a fan oven, but the speed of the air is higher, and it has the sculptured base to the basket, then my wife puts a rubber like thing inside the basket, so the basket does not need washing, which means the air is not being circulated as designed, then she wonders why it takes longer than the instructions say.

I have failed to get her to understand why she should not use the rubber things.

 

[ericmark]

There was a piece on TV, this morning, which suggested that the on all the time clock display, of a microwave oven, actually costs more per day, than actual cooking in the oven.

This is what the article also said. I will put an energy monitor on it, but don't believe it.

 

[Harry Bloomfield]

This is what the article also said. I will put an energy monitor on it, but don't believe it.

0.25 watts (at a guess), vesus our 4 minutes of daily use, rated 700w (I don't know if that's the energy input, or output.

 

[JohnW2]

The microwave is vented, and heat is lost all the time it is running, the air fryer recirculates the hot air.

In an air fryer, it is the hot air which does the cooking. However, the air in a microwave doesn't have to be hot at all, and only warms up a little as a result of heat escaping from the cooking food. I would therefore expect that heat losses from a microwave in the manner you describe would be pretty small. ... and it's not just 'venting' - the casing of our air fryer gets pretty hot (hence losses into surroundings), whereas the case of our microwave hardly gets warm - so, particularly given the generally much shorter duration of microwave cooking, again leads me to suspect that heat losses will be much less with the microwave.

However, given that conversion of electricity into heat is essentially 100% efficient, the lack of 100% efficiency of heating food does not represent 'wasted' energy during the Winter, since it merely heats the house. However, in terms of cost, if the alternative means of heating the house is gas, that would usually be much cheaper ... and, of course, in Summer, both energy and cost are 'wasted'.

 

[JohnW2]

There was a piece on TV, this morning, which suggested that the on all the time clock display, of a microwave oven, actually costs more per day, to run, than actual cooking in the oven.

Who knows, but in the case of our microwave, it would have to be the electronics in general, not the 'display', which was using energy, since the display switches off after a minute or two of 'inattention'.

Our microwave, tends to get perhaps 4 minutes per day of use, on full power.

Well, yes, as with any "standing charge" situation, the impact of that 'standing charge' becomes much greater if one's usage is very low.

 

[JohnW2]

0.25 watts (at a guess), vesus our 4 minutes of daily use, rated 700w (I don't know if that's the energy input, or output.

Again, who knows, but one would like to think that even 0.25W was a lot more than some trivial electronics would (should) consume - that being 50 mA for 5V electronics.

 

[Jurassicspark]

There was a piece on TV, this morning, which suggested that the on all the time clock display, of a microwave oven, actually costs more per day, to run, than actual cooking in the oven.

And I wonder how long they used the heating function on the microwave.

And how modern was the clock display?

And how was it configured?

Did they really show these on camera?

Seriously though, heating food requires hundreds of watts, regardless of the setting used, easily surpasses the clock’s consumption in mere seconds.

I wonder how it resonated with the audience and whether they decided to reflect on it but with other devices similar in nature.

 

[morqthana]

I need to do it again with proper timings, but I recently boiled the same amount of water using an induction hob on a (claimed) 2000W setting and a 2520-3000W kettle.

Kettle much faster than the hob, far more than the difference in power would lead you to expect.

 

[Jurassicspark]

Iwould expect a microwave to be appreciably more 'efficient' (higher proportion of energy used getting into (and 'cooking') the food).

Depends on the food.

I’m sure it’s advised and recommended on which method of cooking is the best.

Well, yes, as with any "standing charge" situation, the impact of that 'standing charge' becomes much greater if one's usage is very low.

But is it much greater here considering the trivial amount consumed by standby.

 

[Why Not Indeed]

0.25 watts (at a guess), vesus our 4 minutes of daily use, rated 700w (I don't know if that's the energy input, or output.

That will be the RF power into the food, I reckon [unless it really is tiny].

My "900W" microwave uses 0.9W idle, 1.5W with the door open [the bulb is broken] and 1600W in use.

So uses as much at idle in a day as about a minute's worth of use.

 

[JohnW2]

I need to do it again with proper timings, but I recently boiled the same amount of water using an induction hob on a (claimed) 2000W setting and a 2520-3000W kettle. .... Kettle much faster than the hob, far more than the difference in power would lead you to expect.

Electric kettles these days tend to be very light, often plastic, and hence of low thermal capacity. Heating on the hob was probably done in a relatively heavy metal saucepan/pot (or maybe kettle), probably of much higher thermal capacity? If so, I suspect that at least some (maybe most?) of the difference would be due to having to heat up the 'heavy metal utensil'?

 

[Harry Bloomfield]

But is it much greater here considering the trivial amount consumed by standby.

Based on my guessed numbers 0.25w standby, 700w for 4 minutes. 6wh for the display, 47wh for the cooking per day.