{"id":2916,"date":"2010-04-06T09:47:45","date_gmt":"2010-04-06T13:47:45","guid":{"rendered":"http:\/\/www.schollnick.net\/wordpress\/?page_id=2916"},"modified":"2013-07-12T08:54:44","modified_gmt":"2013-07-12T12:54:44","slug":"saving_electricity","status":"publish","type":"page","link":"http:\/\/www.schollnick.net\/wordpress\/home-automation\/saving_electricity\/","title":{"rendered":"Saving Electricity? Saving money? Parasitical Energy use?"},"content":{"rendered":"

One of the easier methods to save money, is to cut your energy consumption… \u00c2\u00a0But beware, this is an area of diminishing returns… \u00c2\u00a0Yes, automating your water heater, to turn off the heater when not in use will save a bit of power, but you end up having to wait for the Hot Water… \u00c2\u00a0Instead a Tankless hot water heater might be a better choice…<\/p>\n

[toc=”2,3,4″ title=”Table of contents”]<\/p>\n

Also, all the Automation devices have a slight power draw… \u00c2\u00a0But more on that later in this page..<\/p>\n

Identify your Power Usage<\/h2>\n

First, you need to find how much energy an item is using. <\/strong>For most devices you can just look at the label!<\/span><\/strong><\/span><\/strong>Nearly everything you can plug into the wall has a label that says<\/span> how much electricity it uses. (It may be printed directly into the plastic or metal.) You may have to hunt for the label. It’s often on the bottom or side of the device, or possibly where the power cord enters the unit. If the device is powered with an AC\/DC adapter, the electrical rating is usually listed on the adapter itself.<\/p>\n

If the label only gives the number of amps and not the number of watts,<\/strong> then just multiply the amps by 120 to get the number of watts.\u00c2\u00a0(Amps x Volts = Watts, and most U.S. electricity is 120 volts. So a hot plate that uses 6 amps uses 6 x 120 = 720 watts. Most other countries use 240 volts instead of 120, so outside of North America and Japan use 240 instead of 120 in your calculations.) Note that if a device is powered by a transformer (one of those great big plugs), then the transformer has converted the electricity from AC to DC, so you need to multiply by the DC voltage, not the AC voltage of 120. For example, if the device says “INPUT 9V, 0.5A”, then that’s 9 volts x 0.5 amps = 4.5 watts.<\/p>\n

You may have noticed that appliances may be labeled 110, 115, or 120 volts.<\/strong> Appliances are actually designed to accept a range of voltages, between 110-120 volts, and the exact voltage coming out of your electrical socket can vary depending on conditions at the power plant and in your own home. Let’s just agree that when we say 120 volts, we understand that it’s actually a range from 110-120. And just use 120 for your calculations (unless you’re outside of North America or Japan, in which case you probably have 240 volts).<\/p>\n

Your device might actually list a huge voltage range, like 100-240V.<\/strong> That just means that it will work with any country’s voltage. For your calculations, use the voltage for the country where you’re plugging the device in.<\/p>\n

Some important caveats:<\/strong><\/span><\/p>\n

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  1. The amount of electricity listed on the label is the\u00c2\u00a0largest<\/em> amount that the appliance will ever use.<\/strong> For example, a 300-watt refrigerator will only run at 300 watts when the compressor’s running (which is when it makes that humming sound, indicating that it’s actually chilling the air inside). Most of the time the fridge just sits there, using only 5 watts or so for its electronics. If the amount of work done by a device varies up and down, then so does its energy use. (e.g., a stereo that can be turned up or down, an oven that can be set at various temperatures, a fridge that sometimes runs and sometimes doesn’t, a computer that sometimes spins its various drives and sometimes has to use more of its brainpower, etc.) The label on computers is particularly useless; a computer labeled at 300 watts probably uses only about 100. In just a bit we’ll cover how to measure the actual amount of electricity being used by a device.<\/li>\n
  2. Many consumer items are advertised according to their power\u00c2\u00a0output, not\u00c2\u00a0input.That means the stereo that says 30 watts on the box might actually need 50 watts to make 30 watts of sound (assuming the volume was cranked), and your 900-watt microwave oven might actually use 1400 watts (on its highest setting). That’s because all electrical devices are inefficient — they have to use some extra energy to do what they do.<\/li>\n
  3. Knowing how much electricity a device uses at a given moment doesn’t tell you how much it’s using in a month, because it’s probably not running 24\/7<\/span> (and if it\u00c2\u00a0is running 24\/7 like a fridge, it’s probably not using the greatest amount of electricity, as we discussed earlier). To measure how much electricity something uses for a certain period (like a week or a month), you can use a watt-meter<\/span>.<\/span><\/strong><\/li>\n
  4. Some devices use a small amount of electricity even when they’re not on. For example, VCR’s and microwaves draw a small amount to power the time display. This amount is often 5 watts or less. Devices which run off transformers\u00c2\u00a0also draw a small amount of power.<\/span><\/strong><\/li>\n<\/ol>\n

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    And of course, electricity consumption of a device varies from brand to brand, and condition to condition.<\/span><\/p>\n

    Electrical usage of household items<\/h2>\n
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    TYPICAL WATTAGES OF VARIOUS APPLIANCES
    \n(From\u00c2\u00a0energy.gov<\/a>)<\/h4>\n

    Here are some examples of the range of nameplate wattages for various household appliances:<\/p>\n