I think it’s really useful to flip the paradigm. To call all the energy used for heat the thing that wanted when it’s wanted and all the computation be it for Bitcoin or AI model building the extra benefit. The “waste” would be the amount of energy going towards computation vs heating up a simple tungsten wire. The difference is that chips cannot be heated to boil water or fry veggies but it can be used for warm water, warm air and even dehydrating which is already a lot of opportunity to replace tungsten with silicon. 

 yes i read about a swimming pool heated with a crypto mining rig - i like that idea a lot.  however modern heating technology is based on heat pumps which are at least 2X more efficient than resistive heating.  mining rigs are resistive in terms of their performance as heaters. 

 Heat pumps use compressors only? No heating elements? 

 heating elements may sometimes be used to defrost the coils in winter but for the most part yes - heating pumps are based on compressors.