For the record...watts are joules/second (where joules are a measure of energy). So multiplying
watts and hours, you get a scaled measure of energy. Electric meters, for example, either on the
side of the house or in the basement are measuring kW-hours, or again, a scaled value for energy.
It might have made sense to redo the electic meter display for Joules, but I guess kW-hours is
more traditional.