Portable Power Meter
These plug-in power meters are low cost and great for checking appliances etc.
You can move them around, leaving connected to each appliance or a group of appliances for a week or so and see where all the power money is going.
Switchboard mounted Portable Power Meter
I have another electronic power meter on the switchboard that meters all power except the hot-water. Over the last 5-days I have recorded power use and noted that it was only half of what our power supplier thinks it is. Adding in some hot water, I think there is still a large difference. I wonder if this is due to power factor?
In the process of collecting up the info I noticed that our power-factor on some equipment is not as good as it could be and we may be paying quite a bit more for power than we need to. I will have to put a meter on the hot water and do some more research.
Note: You need an electrician to install this type of switchboard mounted power meter.