Is there a way to use X10 modules to read the current drawn at the panel? I would be fine with just a single measurement for the whole house (I don't need things broken up by circuit). I saw a thread where the water heater was monitored, but I'm not really clear on how that worked.
With X10 the best you can do is apply and disconnect power, which dosn't tell you much unless you want to do some major hacking.
The iMeter X10 program sounds interesting. You need to put a current transformer on your major electrical appliances you want to monitor (water heater, electric furnace, heat pump/ air conditioner outside unit, dryer, etc.) the current transformers get connected to X10 PowerFlash units. When the major power consumer turns ON the Power Flash sends a HCUC address "ON" signal to Active Home Pro which then logs it's status. I haven't looked at iMeter X10, but I assume it allows you to input how much power the appliance uses when running and then uses the run time and kWh $ to calculate cost.
Do you have a heat pump with electric heat back up, or just straight electric heat? If you have a new heat pump, find out at what outside temp the heat pump is being locked out. If it is high, like 30 degrees, you can knock it down much lower. I just bought a new system where the pump is never locked out, although I don't know how much the heat pump can do with outside temp below zero.
Tuiceman is correct about the electric furnace being the largest consumer of power and water heater second.
FWIW years ago we had a hot tub which stayed hot all the time. I found a 120V hour meter at a surplus shop and using a 220V to 120V transformer wired it across the heater. I kept a weekly log and calculated kWh each week. Cheaper than TED but more work.
