Yeah sure, in the practical sense different terms are established for the different applications, but that doesn't change the fact that what you call a "heat pu

Yeah sure, in the practical sense different terms are established for the different applications, but that doesn't change the fact that what you call a "heat pump" works by the same principle as what you call an "air conditioner". I was more refering to the general thermodynamic principle of a heat pump and it appears that others too use the term in that general sense. Citing from Heat Pumps in Chemical Process Industry (by Kiss, Infante Ferreira) [1] > Notably, the term heat pump is more generic; it applies to many heating, ventilating and air conditioning (HVAC) devices used for space heating or cooling. When used for heating, a heat pump employs the same refrigeration-type cycle ... "When used for heating" clearly indicates that the term is valid for both types of applications. > And in either case the thermodynamics situation is simply the second law: it takes energy to do all that work, which turns into heat. You better read up on what the second law means. What you write "takes energy .. which turns into heat" is actually linked to the first law. > Sure, the energy from a fossil fuel was originally solar power, but that was millions of years ago. You can’t just magically claim its part of the current energy balance. I am not making that case. The claim I am making, is that it doesn't matter for what kind of purpose you use this fossil energy (except for the weird uses I mentioned) because _all_ purposes will eventually turn it into heat. Which is why I reject the claim that "AC heats up the planet". No, fossil energy use does, no matter what you use it for. > The significant contribution of air conditioning to heat islands has been widely discussed for decades. Your original claim was "AC heats up the planet though". Now you write "heat islands". Yeah, of course you have heat islands. I don't deny that. It's just something totally different from "heating up the planet". Because transferring heat from inside building to the surroundings doesn't change the planet's _thermal_ energy balance. It's the burning of fossil fuels that does so. [1] https://www.google.com/books/edition/Heat_Pumps_in_Chemical_Process_Industry/zx8NDgAAQBAJ?hl=en&gbpv=1&printsec=frontcover&bsq=heat%20pump%20generic https://www.google.com/books/edition/Heat_Pumps_in_Chemical_...