What does it cost to bake my bread?
I have sometimes felt a bit guilty about baking in the summer when it is really hot outside. Wouldn't it be cheaper if I bought a small oven for baking my mostly tiny test loaves? So, being a total nerd I decided to estimate how much it costs.
Duke Energy provides access to my daily energy consumption and by consulting my GitHub repository I can determine when I baked. I collected the data from July 20 to August 21. I baked 16 times over that interval.
My first question was did we use more energy on days I baked than on those that I didn't? The answer was yes, about 2.5 kilowatt hours more.
The second question was could this be simply random fluctuation? Only about 20% of random assignments of baking days have greater mean power consumption. Not a publishable result but better than random. I'd need to collect more data to nail down better.
My final question was supposing this is correct how much does it cost? My electricity cost about $0.13 per kWh so it cost about 34 cents to bake a loaf of bread in the summer.
I'm going to stick with baking my big oven.
Details:
- This is the total energy used including the air conditioning required to keep the indoor temperature at 78F.
- I'm baking in an old JennAir electric oven at 350F.
- I typically bake for 30 minutes + about 10 minutes of preheating.
- My house has central air.
- I live in central North Carolina where the air conditioning runs nearly every day.
Gary
FWIW - with an old oven - cost - including time - is about half of the cost of a loaf of bread - cheap bread! Enjoy!
Interesting, Gary. For my last electric bill I paid $0.147 (US) per KHh, all fees and taxes included. Typical home ovens run 3 - 5 KWh. KW. Counting preheat time, a baking session of mine would be around 1.45 hours, or 5.8 KWh using 4 KW as an average. That would cost $0.85. Note that I pre-heat my baking steel for a long time at 450 deg F. Baking in a loaf pan without a steel at a lower temperature might cut that in half, roughly, to $0.425.
Reasonably close to your SWAG, I would say.
TomP
I did a similar estimate but realized that the duty cycle of the heating element was an important factor that I didn't know. I could stand there and time a few on-off cycles but then I'm missing the air conditioning load.
I have read that for data centers it takes 3 watts of cooling for every 1 watt of heat. If that's the case at my house then I'm only using 600 Wh for the oven? That seems low to me.
My number may be off since I'm not controlling any other loads in the house but I hope that by averaging over many days I'm compensating for that.
In the winter the cost will be lower because the heat is going to good use.
The bottom line is that compared to what I spend on ingredients and gear the electricity is a trivial component of my baking hobby.
Gary
I think the air conditioning load will be about the same whether the oven has cycled on or off since the oven will still be emitting about the same amount of heat. The AC cost should be a smallish fraction of the cost of electricity to generate the heat, maybe even 1/10.
You are really close again. After a journey into strange units I learned:
If I did that correctly, the air conditioning adds about 25% to the power required to bake.
Gary
I started on the same route but once I realized how small the extra cooling cost would be I didn't bother to take the last step or two.
If someone got a countertop oven thinking they would save on electricity costs, they would be baking a *lot* of bread before recouping the purchase cost.
whether standalone or in the form of a bread machine, can easily be put out on the porch in the summer, taking their heat load out of the house completely.
The BM's which bake the best draw 500-700W while baking, quite a bit less electricity than a built-in oven. And with their small volumes, they're MUCH more efficient. I haven't quantified it in detail, but I would guesstimate they use 1/6 the elec as a built-in electric oven.
mine💕💕💕doesn't heat up the kitchen nearly as much as the big oven does. It only affects its surrounding area and cools down much quicker with a blast from a floor fan.
Yippee
I stood in front of my oven with a stopwatch and measured the time it was heating (there is a visual indicator) during a 45 minute bake of 1 kg of dough in a 2 L Pullman pan.
After the 8.5 minute preheat the oven was heating for 26% of the 45 minute bake; a duty cycle of about 1:3. During the 2 hours it took to bake and cool down my excess energy consumption was 1.25kWh or about 18 cents.
A large well insulated box might actually use less energy than a small uninsulated box.
Gary
Even lower than we had first guesstimated. Basically, it's just not a cost factor in the overall cost of making a loaf of bread. Heat in the kitchen during hot weather, that's a different matter.
If one thinks about making bread at home to sell, say, in a farmer's market, the cost is dominated by how much you want to get for your time and expertise.