Okay a related question: I have a toaster oven and a new electric regular oven. The toaster oven is not very insulated or tightly sealed but it is small. If I am making meatloaf for two and it fits in the toaster oven then is that less waste heat and energy because it is smaller, or more because it is radiating and leaking more, thus on more of the cooking time?
It will depend on the exact size, insulation characteristics and power usage of the two ovens. Obviously for a toaster oven that is 1 millimeter smaller than the regular oven, the lack of insulation will dominate and it will heat the house more than the regular oven. A pretty good estimate can be obtained by comparing the average power usage of the two ovens when in operation. Whichever uses more power will heat the house more. For realistic ovens and toaster ovens, I would expect the regular oven to use more power and to heat the house more.
I think it is important to be clear about what you mean by ‘heat the house.’
If you are talking strictly about how much thermal energy is transferred into the building, then I would tend to say that (relatively inefficient) ovens are worse. However this depends on whether either of them have extractor fans sending the hot gases outside, which would change everything.
If there is no external extraction, then the insulation of the oven is irrelevant. All heat generated in the oven will eventually end up in the house.
However, this is where the question of ‘heat the house’ comes into play. If by heat you mean perceived warmth, then a well-insulated oven may be better as the heat will dissipate over a much longer period of time than an open stove.
Thank you! This has been bugging me since the OP 3 days ago but I’m always catching up on this thread on my phone, where posting an essay screed is too hard. Lucky for you all.
If your air conditioner is adequate to your house’s needs, running the oven doesn’t “heat the house”. It makes the air conditioner run more. So it adds cost to your month, but no discomfort to your day.
Of course, no home air conditioner has perfectly uniform distribution, so there will be a warmer area in your kitchen. If you’re hanging out there, your perception will be the house is hotter. OTOH, if you’re hanging out n some other room, your perception may well be that the house is cooler, because now the room you’re in is being overcooled by the AC’s less than perfect air distribution.
Now if you live where air conditioners are rare but are now needed due to AGW, or you can’t afford to own or run one, that’s a different story. For sure now your goal is adding as little heat as possible as slowly as possible, and probably mostly while it’s as cool as it gets, so at night and preferably while you’re asleep and so out of the kitchen.
Not irrelevant, because if it’s well insulated, it won’t have to generate as much heat in the first place.
I think you took my quote out of context. I had already posited that the oven was relatively less efficient and when I said that the insulation was irrelevant I was speaking only in the context of heat dissipation.
(though technically speaking, if the oven had 100% perfect insultation and was never opened, the heat would be contained for infinity. But then the OP’s pot roast would be jerky)
Well, obviously “never opened” is unrealistic. But it could still heat up once, hold the heat inside for the duration of the cooking, and then release the heat when it’s opened, as opposed to needing to constantly generate heat to match continual heat loss and maintain the desired cooking temperature. For a long, slow cooking, this could be significant.
just to be clear, I am not saying that an oven can’t ever be efficient. What I am saying is that if it isn’t efficient, even good levels of insulation will not stop the heat energy from entering the house and increasing the thermal load
It will but not that much and through numerous paths around the house. If the pan is covered you don’t need much airflow to pull the heat away. I have a variable speed exhaust fan and just a slow fan speed pulls the heat away. I can’t do that using the oven.
Except for boiling any water in the food.
Depends on what you mean by heating the house. If you mean “X joules of excess heat energy enter the house” then yes. If you mean “the house is X degrees hotter” then probably not. Think 1 degree warmer for 12 hours vs 10 degrees warmer for 30 minutes.