Would turning off standby devices increase my heating bills?

29 January 2012

Question

Hi,

I've been pondering about the following; We are often told that we can gain large energy savings by shutting off all those transformers and stand-by devices, such as televisions, computers, printers etc., in our homes that are using energy. Instead we should turn off the devices by the master switch or pull it out of their sockets. However, when a device, e.g. a transformer is using energy that energy must be used for something, and it seems to me that in the end all that energy will be converted into heat.

Now, if my home is heated solely by electricity, electric radiators etc., would I still have any savings by turning off all those stand-by devices? My point is that if the energy used by those devices are eventually turned into heat anyway, it must all contribute to heating my house. Does it make any difference whether that heating comes from devices designed for heating or if it comes from "second hand" energy?

Thanks for a great show,
Jakob

Answer

We posed this question to Cambridge University's David MacKay...

This myth is true for a few people but only during the winter, but it's false for most. If your house is being heated by electricity through ordinary bar fires or blower heaters then yes, it's much the same as heating the house with any electricity wasting appliances. But if you are in this situation, you should change the way you heat your house. Electricity is a high grade energy and heat is low grade energy. It's a waste to turn electricity into heat. To be precise, if you make only one unit of heat from a unit of electricity, then that's a waste. Heat as called air source heat pumps or ground source heat pumps can do much better, delivering 3 or 4 units of heat for every unit of electricity consumed. They work like a back to front refrigerator, pumping heat into your house from the outside air. For the rest of us whose homes are heated by fossil fuels or by biofuels, it's a good idea to avoid using electrical gadgets as a heat source for your home. At least for as long as our increases in electricity demand are served by fossil fuels. It's better to burn the fossil fuel at home. The point is, if you use electricity from an ordinary fossil power station, more than half of that energy from the fossil fuel goes sadly up the cooling tower. Of the energy that gets turned into electricity, about 8% is lost in the transmission system. If however, you burn that fossil fuel in your home, then more of the energy goes directly into making hot air for you.

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