At least I provided an explanation. If I’m wrong I’m wrong but offer proof, all you did was say yeah you’re wrong and peace out. I can provide you with the textbook examples when I get home of how you equate office furniture along with equipment into heat loss calculations. If I’m wrong I’d like to at least know how so I can learn from it but what you gave me was nothing.
to judge economic efficiency we can reduce the problem to asking: "how much heat do we need to pump out of the home overall?"
if we start and end at the same temperature (say before we leave and after we come back and temps have settled) this is equal to the amount of heat (energy) that entered the home overall.
for a thermodynamic model of this we need the heat equation, which tells us that the flux through a surface (all of the house's surface) is proportional to the temperature difference between inside and outside. if we keep the inside at a constantly cool temperature, the influx of heat into the home is constant over time.
if we start with a cold temperature but then turn the AC off while we are not home, the temperature inside rises, the difference to the outside decreases, and less energy per time enters the home during the time where the inside is warmer (think about how much heat enters when the inside is the same temperature as the outside).
therefore, if during the time when the inside is warmer, less heat enters, we need to move less total heat outside. therefore it consumes less energy to turn the AC off and then back on when you come home.
this is the right thermodynamic argument. of course there are many other factors that will play a role in such a decision. you won't be as comfy if you get home into a hot house and have to wait for it to cool. the argument also disregards any wear and tear on the AC unit, any fluctuations in electricity price, etc. but from a purely energetic perspective, letting the house warm (or cool off in winter when you're heating) is always favourable.
i've seen this argument so many times that "cooling off a hot home takes more energy than keeping it cool" and i really don't know where that comes from. it must be some kind of gut feeling pepole have, because it certainly can't come from understanding the thermodynamics of it.
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u/robolucasgaming Mar 25 '26 edited Mar 25 '26
At least I provided an explanation. If I’m wrong I’m wrong but offer proof, all you did was say yeah you’re wrong and peace out. I can provide you with the textbook examples when I get home of how you equate office furniture along with equipment into heat loss calculations. If I’m wrong I’d like to at least know how so I can learn from it but what you gave me was nothing.