Welcome to Energy Consumption (someday: direct to the wiki!).
Q: I'm in a hurry and want a decent watt meter
A: Buy a
program it to your highest electricity
rate, and plug it into each appliance for
a day in the "monthly average cost" mode.
Q: Hello, is anyone out there?
A: Yes. You can also contribute via the wiki.
Recent highlights (circa 2012):
Q: WATTS UP? or KILL A WATT ... which should I buy and from
A: I got my first KILL A WATT for $40-something at Radio Shack. I own
four kinds of watt meter now, but the KILL A WATT and WATTS UP? are the
two readily-available products. The KILL A WATT is a consumer-oriented
device designed to plug flush to the wall. It has some interesting
outputs like power factor, hertz, and "VA" (vs. the sine-waved "watts"
average that you actually pay for) that the original WATTS UP? lacked.
The WATTS UP? is built tougher, originally for the classroom, has a nice
6 foot cord, can be programed to your electricity costs, and features a
dollar readout. The Pro model even collects data over time and makes
it available over USB (Windows software or OS X-compatible command line
tool required). It costs more than twice as much, but the WATTS UP? 2.0
seems accurate to a tenth of a watt (above a watt or so, depending on
Power Factor, etc) and now (in the 2.0 version) has even more geeky
readouts (like duty cycle) than the KILL A WATT.
Not to be outdone, The KILL A WATT now has an "EZ"
version that calculates costs over time and costs much less than the
Watts Up?. While the math is easy enough to do, you will gather
significantly more useful data if you buy the EZ or Watts Up?
2.0 which do math for you (e.g. running average cost/month).
folks claim that their meters are superior at lower wattages
(<=10W?). That may have been true (particularly of the original
non-tenth-of-a-watt Watts Up? 1.0 which is truly confused by low
wattages and distant-from 1 power factors), but my tests showed no
significant difference between Brand® meters and the KILL A WATT or
WATTS UP? 2.0. In my experience and testing these two readily-available
mass-produced meters are good enough to figure out what you want to
know: should I -- perhaps automatically -- switch off the power strip to
this thing when I'm not using it? How much does my entire entertainent
system/computer desk draw ... even when it is off? For small, lower
wattage devices, I cross-check the amount of emitted heat: power bricks
in particular are usually warm at 2-5W. Energy Star appliances,
including some replacement power bricks from Radio Shack do not get as
warm / don't waste as much energy.
If you just want to measure your stuff and then share it with
friends, a KILL A WATT is great. If you think you'll be helping others,
spring for the WATTS UP? 2.0. I've found both in retail stores (like
Fry's), but usually you have to order them online (see links at the
left). FYI, EC.org supporters have had bad service experiences with
SupermediaStore.com and the Brand® folks (who, at least in the past,
built their own meters -- with not the best qualitiy controls).