I ordered a wattmeter for the shop and it just arrived. Let the fun begin!
Basically a voltmeter and ammeter rolled together, a wattmeter will tell you just how much electricity a device is using. This is a useful capability to have in the shop as our industry is becoming increasingly aware of power consumption. As you will see, computers use a fair bit of juice.
The meter I’m using is the well known Kill-a-Watt meter. You can get them for about 40 bucks or so. It claims to be accurate to within 0.2 percent. For my purposes, this is more than accurate enough.
Part of the reason I have set out to do this is because I feel the waste of TVs and small electronic devices is somewhat overstated. It’s an issue, yes, but not as bad as the BBC article makes it out to be. I’ll qualify this more later. Here are some of the results I got.
Appliances
- For the sake of reference, one of the first things I tried was a 40W light bulb. When lit it used a steady 38W of power.
- I didn’t test it long enough to to figure out it’s kW/h rating, but our small bar fridge takes 115W when it is going. Bar fridges seem to spend as much time on as off.
- Our air compressor, typical of a small workshop compressor, requires 236W when it’s compressing. It does this for maybe 15 minutes in the day.
Electronics
- My cell phone power supply charging the phone while it was on: 2W
- My old crappy Kodak digital camera: fluctuated between 3 and 10W depending on what the camera was doing. The transformer consumed 1W with nothing hooked up to it.
- My DVD player playing: 7W; standby: 1W
- My 27 inch television, watching Mythbusters: 70W; standby: 1W. Oddly enough, CSI only required 67W. I have no reasonable explanation for this.
Computer Peripherals
- 17 inch MAG CRT monitor, on: 65W; standby mode: 2W
- 17 inch Viewsonic VA702b LCD flat panel screen, on: 20W; standby: 1W
- Small cheapo computer speakers: 1W
- Big cheapo computer speakers: 2W
- Really big computer speakers: 5W
- Linksys WRT54GS wireless router and access point: 5W. Its power transformer also ate 1W even if nothing was hooked up.
Computers
- A mid-range Pentium 3 desktop (800MHz) idle: 55W; full-load 80W; standby: 3W
- A Pentium 4-M Laptop, 1.6GHz, booting WinXP desktop: 85W
- My 850MHz P3 laptop charging its battery, off: 30W; idle: 35W; full load: 55W
- An FCP Esprit tower. It has an AMD Sempron 2600 and 512MB of RAM. Idle: 50W; full load: 75W; standby: 5W. It’s interesting how its power usage is almost identical to the Pentium 3 even though it’s double the clock rate and quadruple the power.
- A FCP Eclipse from late last year. Key features include an Athlon64 3000+ (Venice), 1GB of DDR, and a GeForce 6600 256MB. Idle: 85W; full load 110W. Playing a game: 100-125W; standby: 8W.
- An FCP Echelon business workstation. This one has a Pentium 4 3.2GHz (Prescott 2M), 1GB of RAM, and an Intel 915G chipset. Idle: 120W; full load: 166W; standby: 10W.
- Socrates is our development workstation, the most powerful computer in the shop tasked for our own uses. It is an AthlonXP 2500 (1866MHz) with 1GB of DDR and two hard drives. Idle: 115W; full load: 133W. Notice how it uses more than the Athlon64.
Our Network Core
Details about it is a whole other blog article I will share one day. The Core consists of all of the equipment required to make our network and Internet go including our router (a rebuilt K6/2 450 desktop), the primary network fileserver (a K6/2 450 with a bunch of hard drives), and a big UPS. It consumes some 185 watts of electricity 24 and 7.
The Lowdown
This wasn’t really a very scientific test, but it certainly gives one a hint about the kind of results to expect from a properly controlled series of tests. One thing that did stand out is standby mode on home electronics is not as bad as the folks in the above mentioned article make it out to be.
Devices on standby do use power. I figure the fifteen “always on” electronic gadgets in my house, excluding the computers, are consuming 20W of power at any given time. Multiply this by the 8760 hours in a year and you get 175,200 watt hours, or 175.2 kilowatt hours per year. While this isn’t nothing, it amounts to very little compared to the refrigerator (450kWh/year) or the chest freezer (500kWh/y), the lights, washer, dryer, climate control… In all, my home uses around 7800kWh per year (considered to be fairly good). The electronic gadgets are eating up only two percent of my total. In my part of the world, this is about ten bucks of electricity.
Now let’s add computers to the equation. There are four computers in my house, three of which are on most of the time. One is a P3 laptop (35W), one of them is a fileserver with no screen (50W) and one of them is my desktop, my trusty P3-800 (55W). Its 19inch screen is powered for maybe a third of the day (89W/3=30W). So the three of them together are worth around 170W. Multiply that by 8760 and you get just under 1490kWh per year. This means 19 percent of my power bill is computers. Even if they were all off for half the day they would still use more power than any other single appliance in my house.
So it’s not the small electronic devices that eat the power, it’s the big ones. The needs of the little things like iPods, PDAs, and cellphones is miniscule compared to computer systems and televisions. In this age of constant information, there are a lot of reasons to leave your computer running all day, every day. Some of the computers at the shop have been basically on for seven years, turned off only for cleaning, upgrades, and the odd power failure. Since home appliance usage tends to be fixed (your fridge is never really not in use) it is the intelligent use of computers and home entertainment equipment, not unplugging your cellphone, which will save the most power.
So how do you save power if the little gadgets aren’t using it? Aside from turning off your computer if you don’t need it, I can think of a few.
- Be reasonable with the thermostat. A lot of people in Canada heat with natural gas, but everyone in Canada cools with electricity. In either case, a power-munching electric motor is forcing that air around. Don’t set the heat above 22 or the A/C below 25.
- Turn off the TV when you aren’t watching it. If your TV is like mine, that’s 70 watts you could be saving.
- Washers and dryers use the same amount of power no matter what is in them. I have noticed that while you can dry four shirts in only 15 minutes, you can dry 40 shirts in 60 minutes. Thus, it is far more efficient to run these appliances when they are full.
- I like to leave the light over the stove on at all times; a lot of people do. I long ago replaced this with a 10W fluorescent light. Same with the light in the living room where everyone hangs out. You should do this with any light in your home which is on for more than an hour a day.
- Turn off your stereo amp when you aren’t using it. It is using power even if it isn’t playing music. If you have a big home stereo, this could be 25W or more.
- Turn off your computer speakers when you aren’t using them. If you have a larger set that’s some 5 watts going down the drain whether your are listening to your downloads or not.
- Make sure your computer is actually telling your CRT monitor to go off when it is not in use. If your screen is like mine that’s 90 watts you won’t be wasting. If you don’t want to have to think about stuff like this get an LCD screen. They use a third of the power.
- I’m sure there are a dozen others I haven’t thought of.