It's still impossible to measure if you are getting into semantics here. How much energy does it take to keep the coinbase servers running? How much energy does it take to keep the coinbase IT people's houses heated? How much energy does it take to keep the lights on in the coinbase office? That's also impossible to track if you wanted to jump down the B.S. rabbit hole.
Financial institutions offer a vast array of services, safeguards, and functionality and significantly higher transactional infrastructure versus Bitcoin/cryptocoins.
Exchanging cash versus submitting a Bitcoin transaction would be more on par.
Existing financial systems process many orders of magnitude more transactions than Bitcon does. There's no acceptable excuse for its current consumption VS the throughput it provides.
Honestly it's really unlikely that bitcoin will be the place where energy efficient cryptocurrency will be debuted.
There's lots of people working on more energy efficient, yet still secure cryptocurrencies, but IMO we won't see truly energy efficient cryptocurrencies until we shift the trust away from the central chain and into individual actors.
Theoretically you should be able to establish a trust coefficient for an action given the signature of the actor & the gossip on the network about their outstanding debts, their current balance & their non-transferable value.
You'd still need to pay the cost for obtaining the information about the actor and a method for verifying that you haven't been subjected to a sybill attack w.r.t. that information, but that amount of data transfer/computation should be orders of magnitude lower than the current PoW technique that bitcoin uses.
There's no way that the rough system I am talking about would be adopted by bitcoin, and I'm not gonna be working on it, I haven't seen a project that looks similar so I'm guessing it will still be quite some time.
If I was going to go with a cryptocurrency that is energy efficient and currently exists I'd probably take a serious look at https://www.nanode.co/
Existing systems, banks and all adjacent institutions and companies, are close to impossible to track and measure.