>I would guess kWh/yr is an extension of this idea. you could use J/yr, but most people don't have an intuitive sense of how much power that is. Just using kW

>I would guess kWh/yr is an extension of this idea. you could use J/yr, but most people don't have an intuitive sense of how much power that is. Just using kW for your average power usage over a year seems more intuitive to me.