Measuring your energy usage

Sales brochures and the energy labels will give you an idea of how much energy each device in your house should use — but how much they actually use in practice depends on how they are run and for how long. For example you might run your fridge very cold, or relatively mild; your dishwasher might get used every day, or only once or twice a week; full or with just a few dishes in it. These variations have major impacts on how much money you can save by changing appliance.

One of the easiest ways to measure how energy hungry your appliances actually are is to use an electricity monitor. These come in a huge variety of types and sizes from portable digital displays of the home’s total energy usage, to plug-in monitors or power meters. The plug-ins are probably the most useful in assessing your appliances. Most work by acting as a link between your plug and the electricity socket; monitoring the rate at which the power is being drawn from the system (this is measured in Watts).

Even devices that are commonly available for under £20 can also tell you the energy used in kilowatt hours (or electrical ‘units’) for the whole period that you are measuring it. To find out how much this is in cash terms multiply the kilowatt hours by the price of electricity (about 13p/unit in 2010) to get an idea of the money that it is costing you.