Freezer and computer energy use
How much energy does an average freezer and computer use?
Can you tell me how much electricity a typical freezer and computer uses?
Answer from Green Energy Efficient Homes
A 10 cubic foot chest freezer with an ENERGY STAR certification must use less than 315 kilowatt hours per year. Some models use as little as 282 kilowatt hours per year, which works out to about 0.77 kilowatt hours per day. A larger, 15 cubic foot ENERGY STAR chest freezer should use less than 400 kilowatt hours per year, while some use as little as 354 kilowatt hours a year, or just under 1 kilowatt hour a day.
Since ENERGY STAR freezers are required to be at least 10% more efficient than their non-ENERGY STAR counterparts, you can count on a slightly higher consumption for a new freezer that isn't ENERGY STAR certified. And since the minimum required efficiency of a new freezer rises every few years (along with the ENERGY STAR standard, which is always a cut above the base), a freezer from 10 or 20 years ago will most likely use more electricity. For example, I bought an ENERGY STAR freezer (10 cubic feet) almost 20 years ago. It's still in my basement, although it's been unplugged for several years; the sticker on it claims it burns 330 kilowatt hours per year, slightly more than the current ENERGY STAR standard and well above the best freezers.
For computers: an ENERGY STAR laptop should consume about 10 watts when idle, no more than 1.5 watts when plugged in but turned off, no more than 2.3 watts when plugged in and suspended, and less than 40 watts when plugged in and turned on. If you assume a laptop is typically on 8 hours a day and on standby for 16 hours, then it would consume (2.3 x 16) + (40 x 8) or 356 Watt hours (0.356 kilowatt hours) a day, or about 130 kilowatt hours a year.
For a desktop computer you have to look at the computer itself, the monitor, and any other things that are left on when the computer is (for example, the speakers). Of course if you also leave a printer on, that will eat into the energy use as well. Conservatively I would estimate that a tower computer, flat panel screen, printer, router, cable or DSL modem and speakers would, in combination, use somewhere around 150-300 watts while on. If you leave all this on continuously that adds up to a lot of energy: between 1300 and 2600 kilowatt hours a year. That's why it's very important to turn off as much of your computer equipment as possible whenever they're not in use. For instance I have my router and modem on a separate power bar and turn it on when I browse the Internet in the morning; off when I head into the office to work; back on when I get home; and back off at bedtime. That means these peripherals are only on for about 8 hours a day instead of 24. Just doing that saves about 175 kilowatt hours a year - which is enough to run that 10 cubic foot freezer for more than 6 months!
If you want to measure your own freezer or computer energy use the best thing to do is buy a Kill A Watt meter or other home energy monitor. You plug it into the wall, then plug in the freezer, or the power bar for the computer and peripherals, into the meter. It will monitor watts consumed at any given time as well as kilowatt hours consumed over time. Some of the fancier meters even let you punch in your hourly electricity rate (including tiered electricity rates if you pay for time of use) and they give you the exact cost of operating the appliance over time. A great way to figure out whether you need to replace (or just unplug) an old, inefficient freezer, or cut back on your computer use.
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