Perhaps the first step on the road to being green comes from learning a bit more about the various appliances in the modern home and how much energy they actually use. There are a range of home energy meters available for just this purpose, reporting not only current usage in monetary terms, but also estimated CO2 emissions, power consumption and historical data that can be used to identify and cut down during periods of excessive consumption. So what are the options?

Monitoring total home consumption

Home energy monitoring devices have been with us for some time. Gizmag looked at CENT-A-METER back in 2003 and since then we've looked at a number of variations on the theme including the The Energy Detective (USD$145) and Black & Decker’s Power Monitor (USD$99.99).

These devices work by attaching a clip-on sensor to the live cable of an electricity meter and wirelessly transmitting usage to a display unit. It is then possible to see, in real time, consumption rise and fall as devices such as computers, TVs, home audio equipment and various other appliances are switched on or off, thereby identifying those that require the most power.

The Efergy (£50) is another well known example. It features the ability to set an alarm when consumption reaches a preset level, an indication of how much money and CO2 can be saved by being more energy-conscious and support for multiple tariffs.

Not enough to chose from? There are even more alternatives out there doing the same job like the Owl meter (which appears to be a re-branded version of the CENT-A-METER and costs around £35), the Eco Eye (£49.99) and the Wattson (£99.95) which vary in terms of design, response time and additional features to better suit individual requirements.

Incidentally, we were so impressed by the CENT-A-METER that we arranged to keep the test unit after our 2003 review and we can report that after six years of continuous use, it's still happily reporting our energy consumption.

Monitoring individual appliances

For a more simplistic approach to monitoring power consumption of individual appliances or collections of devices on an extension cable, a standalone energy meter such as the Kill A Watt (starting at around USD$24) or the Ecosavers (£14.95) provides a cheap and cheerful alternative to real-time monitoring. This needs to be plugged in between a mains socket and the device in question, simply reporting current consumption levels, cost and operating time to help build up an idea of cost over a set period.

It is difficult to judge exactly how long it will take for an energy meter to pay for itself as to a large extent this depends on how eco-conscious an individual is and how willing they are to use the information gained from the readings. Overall the difference in functionality between products is minimal and price will be a key factor in determining your purchase.

One thing it is sure to do is raise awareness, and it may come as quite a shock to discover exactly how much it is costing to leave a light bulb or two on unnecessarily, bake potatoes in the oven instead of the microwave or leave a collection of devices on standby rather than turning them off at the wall. Potentially an energy meter could pay for itself in less than six months, and anyone who is concerned about excessive usage would almost certainly consider such a product to be a wise investment.