|Device||$/month; 8 hours/day||$/month; always on||Watts|
|COMPUTERS (TOWER ONLY, NO MONITOR)|
|COMPUTER (2012 vintage. IDLE): i7-3770k (Ivy Bridge) 16 GB Ram, 1 SSD/2 hard drives, GeForce GT240||$7.20||$21.60||96|
|COMPUTER (2010 vintage. IDLE): i7-930, 6 GB Ram, 3 hard drives, Radeon R4890||$13.58||$40.73||190|
|COMPUTER (2008 vintage. IDLE): Athlon 64 X2 5000+, 2 GB Ram, 2 TB hard drive, onboard video||$4.32||$12.96||54|
|COMPUTER (2007 vintage. IDLE): Core Duo E6750 2.67 Ghz, 4 GB Ram, 2 500GB hard drives, 8800 GT||$9.02||$27.07||128|
|COMPUTER (2007 vintage. STANDBY S3): Core Duo E6750 2.67 Ghz, 4 GB Ram, 2 hard drives, 8800 GT||$0.24||$0.70||3|
|COMPUTER (2005 vintage. IDLE) : Mac Mini 1.42/512 MB Ram, 80 GB (38 watts CPU full while encoding video)||$0.28||$0.85||16|
|COMPUTER (2004 vintage. IDLE): P4 2.6 Ghz, 2 GB Ram, 2 hard drives, GeForce 6800GT||$7.56||$22.68||107|
|COMPUTER (2002 vintage. IDLE): P4 1.8 Ghz, 512 MB Ram, 2 7200 RPM hard drives, ATI Radeon 8500DV AIW video)||$5.29||$15.88||73|
|COMPUTER (2001 vintage. IDLE): P3-733 MHz, 384 MB Ram, 30 GB 5400 rpm hard drive, ATI Radeon AIW9000||$4.24||$12.71||62|
|Leaving computers on all the time 24/7 can add up significantly to your electric bill, especially if you have more than one (an increasingly common situation). Turn them off when not being used, and try the various sleep and hibernate modes to reduce the consumption. However, the most recent generation computers are amazing in that they use much less power while being many times more powerful that computers from just a few years ago.|
|MONITOR (2001 vintage): Samsung 955 DF 19" CRT||$4.61||$13.82||-|
|MONITOR (2003 vintage): Samsung 192N 19" LCD||$2.38||$7.13||-|
|MONITOR (2003 vintage): Samsung 192N 19" LCD (idle)||$0.07||$0.22||-|
|MONITOR (2004 vintage): Dell 2001FP 20" LCD||$3.13||$9.40||43|
|MONITOR (2004 vintage): Dell 2001FP 20" LCD (idle)||$0.24||$0.73||-|
|MONITOR (2005 vintage): Dell 2405FPW 23" LCD||$3.71||$11.14||49|
|MONITOR (2005 vintage): Dell 2405FPW 23" LCD (idle)||$0.06||$0.19||-|
|The old 19" CRT shows twice the power consumption of a similar LCD. Nowadays, LCDs have pretty much taken over for CRTs. Even so, they still use appreciable amounts of electricity if left on all the time, especially the larger ones. Set those monitors to auto shut-off after 10 minutes idle to save some more money.|
|PRINTER (VAMPIRE) : BrotherHL-5250DN Laser (IDLE)||$0.71||$2.14||8|
|PRINTER (VAMPIRE) : Samsung CLP-325W Color Laser (IDLE)||$0.59||$1.78||7|
|COPIER (VAMPIRE) : Sharp AL-1631 (IDLE)||$0.23||$0.70||-|
|FAX MACHINE (VAMPIRE) : Brother FAX-575||$0.38||$1.12|
|These generally don't consume too much electricity since they are used only occasionally when a printing job comes in. Nonetheless, most of these devices have the annoying habit of consuming electricity even in "standby" mode while not being used. If you have several printers, it can add up. The only alternative is to power them off with their power switch or via a power strip.|
|CABLE MODEM (2012 vintage): Motorola SB6141||$0.45||$1.35||6|
|CABLE MODEM (2000 vintage): Time Warner "Shark Fin"||$0.38||$1.15||7|
|CABLE MODEM (2005 vintage): Time Warner RCA DCM425||$0.37||$1.10||5|
|VIDEO SPLITTER/AMP: ChannelPlus DA-550BID||$0.36||$1.08||5|
|SWITCH: Netgear GS108 10/100/1000 8-port switch||$0.26||$0.79||4|
|SWITCH: Netgear FS116 10/100 16-port switch||$0.41||$1.23||7|
|SWITCH: Linksys EZXS55W 10/100 5-port switch||$0.28||$0.85||4|
|ROUTER(2000 vintage): Linksys BEFSR41 10/100 router/4-port switch||$0.41||$1.23||5|
|WIRELESS ROUTER: Linksys WRT54G||$0.38||$1.15||5|
|WIRELESS ACCESS POINT: Linksys WAP11 (B)||$0.36||$1.08||5|
|NAS: Synology DS110j with 3 TB WD Red Hard Drive||$0.50||$1.50||10|
|WEBCAM (NETWORK): Panasonic BL-C1||$0.06||$0.16||1|
|The usage cost for networking gear is pretty low, with devices such as routers and switches costing $1-2 per month to run 24/7. Nonetheless, there is some money to be shaved off the electrical bill by shutting these devices off when they are not being used, for example at night or during trips away.|
|Plasma TV (2012 vintage): Panasonic 55" (turned on for viewing)||$20.96||$62.87||250-280|
|Plasma TV (2012 vintage):(VAMPIRE) : Panasonic 55" (standby)It is a vampire but a minor one at 15 cents per month||$0.05||$0.15|
|Plasma TV (2006 vintage): Panasonic 50" (0 watts on standby)||$23.62||$70.85|
|Plasma TV (2007 vintage): Samsung 42" (0 watts on standby)||$20.88||$62.64|
|LCD TV (2007 vintage): RCA 26" (0 watts on standby)||$8.12||$24.36|
|You might not want to leave those TVs running if you are not watching them! Luckily these particular models seem to consume essentially zero electricity in standby mode. Other models may behave differently. Note that the newer plasma does use less electricity while running than the older one, even though it is a bigger screen, so there have been some gains in efficiency with the newer technology.|
|OTHER AUDIOVIDEO COMPONENTS|
|DVR: Motorola 8300HD (Time-Warner) It uses about the same amount whether turned on or off. It must be left plugged in during any time period where you want to record a show.||$2.26||$6.79||22|
|DVR: Verizon FiOS VMS1100 It uses about the same amount whether turned on or off. It must be left plugged in during any time period where you want to record a show.||$1.81||$5.42||25|
|RECEIVER (2012 vintage): Yamaha RX-V671 (0 watts on standby)||$2.70||$8.10||46|
|RECEIVER (2002 vintage): Sony STR-DE875 AV (0 watts on standby)||$2.46||$7.40||40|
|AMPLIFIER (2001 vintage): Carver AV-405||$4.39||$13.17||71|
|These devices (ABOVE) can use up quite a bit of electricity. It is best to turn these off while they are not being used.|
|VCR: (VAMPIRE): Toshiba W522||$0.36||1|
|DVD Player: JVC XV-5500||$0.06||$0.20|
|Blu-Ray Player: (VAMPIRE): Panasonic DMP-BD85 (standby)||$0.04||$0.10|
|Blu-Ray Player: Panasonic DMP-BD85 (playing a movie) Unless you watch Blu-Ray movies all day, this won't consume much power||$0.60||$1.80||14|
|Subwoofer:(VAMPIRE) Klipsch SW-8||$0.42||$1.26||5|
|Gaming System: (VAMPIRE) Wii||$0.04||$0.16|
|TELEPHONE: (VAMPIRE): 5.8 Ghz Panasonic Cordless Handset||$0.11||$0.33|
|WASHER: 1 load costs about 4 cents! One load per day:||-||$1.26||-|
|DRYER: (gas) - 1 load costs about 10 cents. One load per day:||-||$2.80||-|
|REFRIGERATOR: 21.6 cubic feet||-||$28.50||-|
|COFFEMAKER: (VAMPIRE) Basic 10-cup.||$0.06||$0.18||1|
This project is dedicated to answer the questions: How much electricity is my [fill in toy of your choice] using and how much is it costing me?
These can be important questions when extra computers, televisions, etc. etc. are installed in the home, as is becoming more common. This is especially true if you happen to live in California, home of some of the highest electricity rates in the USA!
The technical aspects of electricity and its usage in the home are well-documented so we won't go into unnecessary detail here. If you would like to know more, your favorite search engine should yield plenty. Try searching on "how does electricity work" or some such. Or to save you even that effort, try www.howstuffworks.com, this is a really good web site for such education.
The Voltage in the home (for USA) is 120 Volts AC. This is what is supplied by the power company. (The actual voltage isn't actually 120 most of the time, but its somewhere around there.) When plugged into the wall outlet's 120 volts, your various appliances and such consume electricity in the form of Current, which is measured in Amps. The Energy usage, or Power usage, is a function of the voltage multiplied by the amps, or Volt-Amps. This is basic physics 101!
power = voltage x current
So if a device uses 1 amp and its plugged into a voltage of 120, then its power is 1 x 120 = 120 volt-amps. A volt-amp is also known as a Watt.
Since the typical USA home has a bunch of consumer goods gobbling up electricity, lots of watts get used. So rather than deal with large numbers, like saying "This widget used 56,000 watts", it is common to re-factor this by using Kilowatts. One kilowatt = 1,000 watts, so we can say the much greener-sounding "This widget used 56 kilowatts".
Finally, when you pay for electricity, you are paying for your power usage over a given period of time. To make this simple (for billing purposes), the electrical company measures your usage and charges you by the Kilowatt-Hour, or kWh. So, if your widget uses 1 kilowatt and you leave it on for an hour, you just used up 1 kWh.
This answer to this question is not necessarily simple. Yes, you can easily take your monthly electricity bill and divide the total cost by the total kWh used (which is probably easy to find on your bill). Then, you will get your average cost per kilowatt. Here is an example:
Total bill ($85.39) divided by total(kWh (468) total = 85.39/468 = $0.1825 per kWh
Yes, that is indeed a real California electricity bill : If you live pretty much anywhere else, your rate is probably a lot less, even as much as a third less. But then again, you miss out on all the earthquakes. (The rate numbers are updated for 2013).
However, to get a true measure of the cost of a particular device, you should understand its impact on your current usage level. This is because there is not a single rate per kWh. Instead, there are a number of different rates that are added up, and what's more, the more you use, the higher the rates. So if you are using fairly consistent amounts of electricity per month and you ADD ON another device, then the cost for that device will actually be at the highest level you have reached on the rate table. This is what is known as a marginal rate. Since we are dealing here with "toys" that are added on top of the basic stuff like the refrigerator, lights, etc., we will measure cost by the marginal rate. Here is a breakdown of how it works:
There is a "baseline" that is established by the power company. There is a set of different rates for usage up to and beyond the baseline. There is a set of rates for the first 30% above that baseline. There is another set of rates for using 30-100% above the baseline. And there is another set of rates for usage above 100% (or double) baseline. The rates get higher as you go up (Did you expect otherwise??). These rates get complicated to figure out (at least on a California bill) due to the various "delivery-rated charges" and "generation-related charges". But by carefully adding up the rates for each charge for >100% baseline usage, the marginal seems to be somewhere around
The numbers are sure to change as rates fluctuate. For our purposes here we will use a round number of 30 cents per kWh, or $0.30/kWh, as the marginal cost of electricity. Your situation is sure to be different so get out your electricity bill and start calculating if you are curious. And if you live in California or another place with high rates, you probably understand why this web page is being born. In fact, it appears that the marginal rates for electricity over the last eight years (2005-2013) has DOUBLED. The original calculations for this page were made using 15 cents, now the number is about 30 cents! This makes it all the more critical to be aware of electricity usage and take whatever steps possible to reduce the usage and therefore keep the electric bill from skyrocketing. (UPDATE 2014: I found out that the electricty bills in other states may be organized completely differently than the tiered system in California. The basic principles still apply).
This is the tool that was used for all of these measurements. Its easy enough to find on the Internet, and easy enough to buy for $20-30 or so. Its also easy to use, despite the fact that some reviewers make it sound complicated. Basically, you can figure out the energy consumption of any device by plugging the Kill-A-Watt into the wall, then plugging in the device to be measured. From the time you do this, the Kill-A-Watt keeps running track of the kilowatt-hours used and the elapsed time. The only trick is to write down the elapsed time and the kilowatts BEFORE unplugging the Kill-A-Watt, because you will lose this information when it is powered off (no problem if this happens, just start another measurement). Leave it on for what you estimate is a time period that will reflect typical usage of the device (because the power consumption will vary depending on what it is doing, this is more pronounced for things such as computers). When you are done, divide the elapsed time by the kWh and you will have the number of kW that device uses per hour. It looks like this:
total kWh divided by elapsed time = kilowatts used per hour
Once you know this, you can use your rate per kWh (That's why we figured that out above) to figure out how much that device costs per hour.
kilowatts used per hour multiplied by rate = cost per hour
Once you know the cost per hour, you can use some multiplications to get a better handle on its cost per month, a convenient measuring stick since the electricity bill comes once per month. Here are some examples:
cost per hour x 8 x 30 = cost per month if left on 8 hours per day
cost per hour x 24 x 30 = cost per month if left on 24 hours per day
All of these can be conveniently and automatically calculated with a spreadsheet. This is how the tables above were made!
When you plug a device into the Kill-A-Watt, one of the buttons will display the instantaneous Watts that the device is using. This is a useful piece of information that can be gathered quickly. I have observed that this Watt reading tends to be about equal to 1,000 times the kWh reading for a device, that is, if the watt reading is at 125 then the kWh is about 0.125. However, because the energy usage will vary depending on a number of factors, it is recommended to use the capabilities of the Kill-A-Watt to measure kWh over a long time period in order to get the most accurate numbers. Nonetheless, this Watt measurement is useful for a quick visual comparison among different devices, so it is included here for your interest.
Vampires are devices that consume power even while they are turned off and not being used. They stay in a "standby" mode to allow the convenience of a quick power-up, and/or they display digital clocks. The power that is used by each vampire is small, costing less than 25 cents per month by my measurements so far. The problem is, there can be quite a few of them, and the vampire cost can add up to several dollars per month or more. Not all electronics devices are vampires, for example, as far as I can tell most plasma televisions are not consuming any vampire power. The Kill-A-Watt is the best way to identify the vampires. Plug a device into the Kill-A-Watt and leave it off for at least 24 hours to get a typical measurement. The above chart has all of of the vampires that I have identified. In most cases these are devices that are not used that often, so now they are kept completely off by either unplugging them or switching off power via a power strip.