They don't give it in Joules because I have no way of understanding how many Joules it takes to run my 17W bulb for two hours per day - but I do understand rath

They don't give it in Joules because I have no way of understanding how many Joules it takes to run my 17W bulb for two hours per day - but I do understand rather easily how many kWh/day that comes to. So while kWh/day may be confusing from the standpoint of relating it to the amount of coal burned, in point of fact it is the natural unit to use when discussing consumption.