I think there's some application for heating the home, vs the energy to heat the tanks/personal comfort etc.
You can measure the difference between the tank and ambient vs the energy usage.
Takes a lot more heat energy to warm an aquarium that's in a room at 65F compared to 75F if the goal in the tank is 78F. You save heating the whle room/house etc, but the tank's heater is going nuts.
You can use more heaters etc during the winter or over build for that issue also. Still, the energy to keep tanks warmer during the colder months is a dramatic issue in terms of energy usage. More than light energy.