Planning a little holiday getaway this summer? Found someone to check the mail, feed the cat, and water the plants? But have you given any thought to your lonely appliances? No, they don’t need to be tended - quite the opposite in fact.

Everything electrical continues to pull power even when turned off. So consider some practical approaches before heading out the door. Plug electronics such as the television and DVD player into a power bar - then switch it off. Unplug kitchen appliances like the toaster, kettle, and microwave. Of course, some things probably need to stay on unless you are gone for a prolonged period - include the refrigerator and water heater on this list.

Now that electrical matters are on the radar, perhaps it is time to reconsider some year-round domestic arrangements. For a start, it is useful to find out which appliances are the greediest. EnerJar is a handy gadget that measures energy consumption. It won the Greener Gadgets Design Competition in 2008.

The EnerJar describes itself as an open source watt meter, which can measure the electrical draw of any appliance. The appliance plugs into the meter, which then plugs into the wall. An LED display gives the reading.

The design is still preliminary and undergoing further remodelling. However, the current specifications allow easy construction at home, provided soldering and programming is not too intimidating. A schematic is available online. The model is appropriate for 120 Volt AC voltage. There are critical cautionary steps to take with assembly - and these are noted on the plans.

A kit may be available in the future. In the meantime, the designers are keen to see their device used to rethink domestic energy consumption. Recycled parts can be obtained from old appliances. The whole assembly should fit into a jar.

Not feeling so handy? Maybe cautious about safety warnings? There are commercial watt meters available. Working on the same principle, short-term and long-term energy needs can be measured. The longer duration readings are useful for intermittent devices like refrigerators, air conditioners, and so on. The small size of these meters makes them inexpensive. If the entire home is a concern, or there are many appliances running on 240 Volts, a whole-house meter can monitor instantaneous and cumulative energy needs.

A slightly more involved process can give the same information. Using the electric meter on the house (or in the electrical room of an apartment building), it is possible to calculate energy use. See this site for an explanation of this method.

After all, knowledge is power - literally in this case. Not only can you decide what appliances could benefit from being on a power bar, but maybe some older versions should be replaced with Energy Star models. And, upon further consideration, some of those household items may not be necessary at all.