I use 3 S9's to heat my house in the winter. depending on the price of bitcoin, i mine during the summer in my garage if it's profitable, if not, i use at least 1 of them as a space heater in the basement.

i also am using a renewable energy provider, which ends up giving me cheaper electricity in volume compared to the rates from my local provider.

so, yes, to answer your question, it does make sense to mine if you have excess energy. excess energy is wasted energy.