In a house, you are cooling the entire volume of space enclosed so that wherever a human happens to go, they are comfortable. It is still littering, regardless of the scale.
Do you use AC? Or any mode of transportation other than walking? Or any convenience that relies on fossil fuels or grid electricity? Do you use any manufactured products? Eat any food that has been shipped a distance farther than your garden?
I assume (perhaps I should not) that by "littering" you are referring to the production of greenhouse gases. If this is so, I'd like to point out that if you are breathing, by your definition, you are littering with every breath.
Yes, I do all of that. I was only continuing the parent's claim that idling a car for AC is littering. I don't actually believe it is - merely stating in that worldview that airconditioning a house is littering too.
I assume (perhaps I should not) that by "littering" you are referring to the production of greenhouse gases. If this is so, I'd like to point out that if you are breathing, by your definition, you are littering with every breath.