How to Buy an Energy Monitor

Using home energy monitors

Home power meters for monitoring electricity usage come in two basic types: "plug monitors" that measure usage from one outlet at a time and "whole-house monitors" that measure overall electricity usage. You can also use a whole-house monitor to calculate usage and cost of a specific large appliance or devices controlled by a wall switch.

Keep in mind that average savings from using an energy monitor range from about 9 to 12 percent. Some owners report bigger savings, but it's wise to be conservative when estimating the payback period for a power monitor. Of course, the information from a monitor doesn't in itself cut costs -- so the faster you act on new knowledge about your electricity usage, the faster you'll see savings.

• Some monitors offer more detail than others. This is a matter of individual taste. Some owners prefer the simplest possible solution, while others want to see a lot of detail or even prefer elaborate software analysis of usage. Think about your initial goals; you can always get more elaborate if you decide to make this a kind of hobby.

• A plug-in energy monitor may be all you need. This simple home power meter plugs into an outlet, then shows on an LED display the electricity used by an appliance or other device you plug into that outlet. You can reset the monitor to calculate the cost of using a different device you plug into the outlet, and also move the device to different outlets till you've checked all the electrical devices you have.

• For large appliances, consider a whole-house monitor. In addition to keeping a running total of your electricity usage, this type of home power meter can calculate the cost of drying a load of clothes, and can also monitor usage from outlets and fixtures controlled by wall switches. You can read the data on an indoor display.

• Consider installation requirements. A plug-in energy monitor is foolproof if you can reach the outlet to plug it in. Some whole-house monitors only require attaching a sensor to your utility company's meter box; these work with most but not all meters. Others, however, require working in your home's panel box, which can be intimidating for some. However, a professional electrician can usually do the installation in about 15 minutes. 

Google PowerMeter

Some utility companies provide free Smart Meters to their customers; others make them available, but charge installation costs to the consumer. These next-generation meters can send data on electricity usage (about every 30 minutes) to a free online service, Google PowerMeter. You don't get a tabletop display inside the house, but you can monitor usage from any computer with Internet access, even when you are away from home. Google PowerMeter shows real-time and cumulative data about electricity usage and costs, so it's easy to see how to lower electricity bills with the least inconvenience.