The other rarely considered aspect is that a small pump is constantly running which also uses electricity. This still has the potential to lose a considerable amount of energy as the water circulates. Another solution is an on demand hot water pump. Metlund manufactures a device that, at the push of a button, brings hot water to the furthest fixture from the hot water heater. This is how it works.
Hot water is drawn back to the remote faucet by the pump action.
When the water reaches a set temperature at the faucet the pump shuts down automatically. Hot water is immediately available.