There are a few options to meet this need. Currently there are 3 major home energy monitoring systems on the market:
1. Power Cost Monitor
2. Energy Detective
3. Black and Decker Power Monitor
Each of these are designed mainly to monitor whole house energy use in real time and each costs between $100 and $200. A certified electrician should install the monitor (that goes into the electrical panel).
Out of the three, the only monitor that can give circuit specific information is the Energy Detective. To do this, you will need to purchase additional current sensors. A full package including the monitor, display and 4 current sensors (one for the main line and three for the circuits of your choice) costs $455.80! Additional sensors beyond that cost $84.95.
These power monitoring systems - and other tools that work in different ways - may be fun to learn about how energy is consumed in your house or condo. But if your goal is to reduce your home's overall energy usage, you're probably better off first spending money on real measures that reduce usage: air sealing; insulation for your attic, walls and floors; Energy Star rated appliances (especially for fridges and washing machines); upgrade your heating system; etc.
If you're not sure where to start, consider hiring an energy auditor who can provide you with a comprehensive, prioritized list of to-do's that are specific to your home.
Read more on this subject: Power Usage Monitors topic in our topic library.